Proceedings Volume 7143

Geoinformatics 2008 and Joint Conference on GIS and Built Environment: Geo-Simulation and Virtual GIS Environments

Lin Liu, Xia Li, Kai Liu, et al.
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Proceedings Volume 7143

Geoinformatics 2008 and Joint Conference on GIS and Built Environment: Geo-Simulation and Virtual GIS Environments

Lin Liu, Xia Li, Kai Liu, et al.
View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 3 November 2008
Contents: 6 Sessions, 130 Papers, 0 Presentations
Conference: Geoinformatics 2008 and Joint Conference on GIS and Built Environment: Geo-Simulation and Virtual GIS Environments 2008
Volume Number: 7143

Table of Contents

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Table of Contents

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  • Front Matter: Volume 7143
  • Ontology, Semantics, and GML
  • Geo-simulation
  • Virtual GIS Environments and Cyber Infrastructure
  • Location-Based Services and Parcipatory GIS
  • 3D Modeling and Visualization
Front Matter: Volume 7143
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Front Matter: Volume 7143
This PDF file contains the front matter associated with SPIE Proceedings Volume 7143, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
Ontology, Semantics, and GML
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Linguistic characteristics of topographic map symbols
Li Su, Dan-hui Zhou
The use of linguistic model in spatial information has been an important topic discussed in relevant theoretical domain in recent years. On the basis of analyzing the geometrical composition of large-scale topographic map symbols and the geometric and semantic relationships among symbols, system of topographic map symbols was regarded as a two-dimensional graphic language and methods and theories of the linguistics were applied in cartographic language. The characteristics of topographic map symbols were analyzed, the internal structure and constructional rule of topographic map symbols were researched, and the phonetic and semantic structures of topographic map symbols were discussed.
Research on presentation and query service of geo-spatial data based on ontology
Hong-wei Li, Qin-chao Li, Chang Cai
The paper analyzed the deficiency on presentation and query of geo-spatial data existed in current GIS, discussed the advantages that ontology possessed in formalization of geo-spatial data and the presentation of semantic granularity, taken land-use classification system as an example to construct domain ontology, and described it by OWL; realized the grade level and category presentation of land-use data benefited from the thoughts of vertical and horizontal navigation; and then discussed query mode of geo-spatial data based on ontology, including data query based on types and grade levels, instances and spatial relation, and synthetic query based on types and instances; these methods enriched query mode of current GIS, and is a useful attempt; point out that the key point of the presentation and query of spatial data based on ontology is to construct domain ontology that can correctly reflect geo-concept and its spatial relation and realize its fine formalization description.
Research on spatio-temporal ontology based on description logic
Yongqi Huang, Zhimin Ding, Zhui Zhao, et al.
DL, short for Description Logic, is aimed at getting a balance between describing ability and reasoning complexity. Users can adopt DL to write clear and formalized concept description for domain model, which makes ontology description possess well-defined syntax and semantics and helps to resolve the problem of spatio-temporal reasoning based on ontology. This paper studies on basic theory of DL and relationship between DL and OWL at first. By analyzing spatio-temporal concepts and relationship of spatio-temporal GIS, the purpose of this paper is adopting ontology language based on DL to express spatio-temporal ontology, and employing suitable ontology-building tool to build spatio-temporal ontology. With regard to existing spatio-temporal ontology based on first-order predicate logic, we need to transform it into spatio-temporal ontology based on DL so as to make the best of existing research fruits. This paper also makes a research on translating relationships between DL and first-order predicate logic.
Study on uncertainty of geospatial semantic Web services composition based on broker approach and Bayesian networks
Xiaodong Yang, Weihong Cui, Zhen Liu, et al.
The Semantic Web has a major weakness which is lacking of a principled means to represent and reason about uncertainty. This is also located in the services composition approaches such as BPEL4WS and Semantic Description Model. We analyze the uncertainty of Geospatial Web Service composition through mining the knowledge in historical records of composition based on Broker approach and Bayesian Networks. We proved this approach is effective and efficient through a sample scenario in this paper.
The design and implementation of GML data management information system based on PostgreSQL
Aiguo Zhang, Qunyong Wu, Qifeng Xu
GML expresses geographic information in text, and it provides an extensible and standard way of spatial information encoding. At the present time, the management of GML data is in terms of document. By this way, the inquiry and update of GML data is inefficient, and it demands high memory when the document is comparatively large. In this respect, the paper put forward a data management of GML based on PostgreSQL. It designs four kinds of inquiries, which are inquiry of metadata, inquiry of geometry based on property, inquiry of property based on spatial information, and inquiry of spatial data based on location. At the same time, it designs and implements the visualization of the inquired WKT data.
Ontology and rules based model for traffic query
Gang Cheng, Qingyun Du, Qian Huang, et al.
This paper will combine ontology and rule based qualitative reason with real time calculation, designing a combined traffic model of national scope which contains highway, railroad, water carriage, scheduled flight etc. That method follows the sense of people to space, establishes ontologies and rules knowledge base, using concepts, instances, relations and rules of traffic field as the basic knowledge for qualitative reason to discover implicit semantic information and eliminate unnecessary ambiguities. The knowledge from the ontologies and rules provides abundant information for query which can lighten the burden of computation, in the mean time, real-time calculation guarantees the accuracy of the data, has raised accuracy and efficiency of the query, which has strengthened the ease of query service and improved web users' experience.
Query evaluation on efficiently encoded GML streams
Jie Yan, Jinyun Fang, Chengde Han
We consider the growing need for querying GML stream and the bulkiness of textual GML. To get things better, we firstly analyze the applicability of Efficient XML Interchange (EXI) encoding for GML and propose EXI encoded GML. Then we develop the SITPath query language supporting geospatial data types and some rich characteristics inherited from XPath within the constraints of streaming limitation. We subsequently present the streaming query evaluation algorithm and some main parts of EGQ engine that evaluates SITPath queries on EXI encoded GML without decoding in advance. Finally, the experimental results indicate the practical time and space performance advantages of EGQ brought about by the query evaluation algorithm and EXI encoding.
Gstruct: a system for extracting schemas from GML documents
Hui Chen, Fubao Zhu, Jihong Guan, et al.
Geography Markup Language (GML) becomes the de facto standard for geographic information representation on the internet. GML schema provides a way to define the structure, content, and semantic of GML documents. It contains useful structural information of GML documents and plays an important role in storing, querying and analyzing GML data. However, GML schema is not mandatory, and it is common that a GML document contains no schema. In this paper, we present Gstruct, a tool for GML schema extraction. Gstruct finds the features in the input GML documents, identifies geometry datatypes as well as simple datatypes, then integrates all these features and eliminates improper components to output the optimal schema. Experiments demonstrate that Gstruct is effective in extracting semantically meaningful schemas from GML documents.
Automatic geospatial information Web service composition based on ontology interface matching
Xianbin Xu, Qunyong Wu, Qinmin Wang
With Web services technology the functions of WebGIS can be presented as a kind of geospatial information service, and helped to overcome the limitation of the information-isolated situation in geospatial information sharing field. Thus Geospatial Information Web service composition, which conglomerates outsourced services working in tandem to offer value-added service, plays the key role in fully taking advantage of geospatial information services. This paper proposes an automatic geospatial information web service composition algorithm that employed the ontology dictionary WordNet to analyze semantic distances among the interfaces. Through making matching between input/output parameters and the semantic meaning of pairs of service interfaces, a geospatial information web service chain can be created from a number of candidate services. A practice of the algorithm is also proposed and the result of it shows the feasibility of this algorithm and the great promise in the emerging demand for geospatial information web service composition.
Formalized description and construction of semantic dictionary of graphic-text spatial relationship
Yizhong Sun, Xiaolei Xue, Xiaoqin Zhao
Graphic and text are two major elements in exhibiting of the results of urban planning and land administration. In combination, they convey the complex relationship resulting from spatial analysis and decision-making. Accurately interpreting and representing these relationships are important steps towards an intelligent GIS for urban planning. This paper employs concept-hierarchy-tree to formalize graphic-text relationships through a framework of spatial object lexicon, spatial relationship lexicon, restriction lexicon, applied pattern base, and word segmentation rule base. The methodology is further verified and shown effective on several urban planning archives.
Integration of GIS: a showcase study on GML based WebGIS
Tohid Ahmed Rana, Murat Komesli, Tuncay Ercan, et al.
The growth of Geographical Information Systems (GIS) emerges as analytical decision-making tools utilizing highly specialized geographic data. However, a simple system still does not exist for the integration/sharing information among GIS. Different organizations working within various domains have built their own data models for collecting and analyzing data. Many data storage, analysis, and delivery issues have prevented these organizations from effectively sharing their data. This presentation aims to show how to share the geo referenced information by utilizing GML (Geography Markup Language) technology among heterogeneous GIS. At present, the updates are retrieved manually; often failing entirely results in information loss and major inconsistencies or referenced data set can be purchased from geographic information producers. The problems and expense associated with the integration of updates for geographic databases are documented. Moreover, a showcase study on a GML based Web-GIS application system has also been developed in order to show how to share geographic information by using GML. The application includes various coverage layers online maps, important textual information and selected case studies
CityGML: a bridge between GIS and urban planning
Yan Zhu, Ti-yan Shen, Sheng-bing Zhao
GIS shows great potential for supporting kinds of decision and management functions that lie at the heart of the planning process. However, data sharing and integration between GIS and urban planning are always problematic. This paper analyzes the root causes of the problem. Then, for finding a fundamental solution, the paper introduces an open data model-CityGML and its application in urban planning processes. As proof of concept, an initial prototype is designed to demonstrate the data sharing and integration based on CityGML.
Design and implementation of GML applied technology services framework
YuTing Sun, Shuliang Zhang, Yu Wu, et al.
As an XML-Based markup language, Geography Markup Language (GML) is a tool of storing, modeling, transferring, and exchanging for spatial data interoperability. More business organizations and researchers apply themselves to researches on GML applied technologies. However, after the analysis of these research results, we find that the interoperability of these research results has become a limitation in the development of GML applied technology. After analyzing OGC Web Service (OWS) framework and Web Services protocols related, this paper designs and implements a GML Applied Technology Service Framework (GATSF) to solve the interoperability problem mentioned above. In the end, this paper gives an example of prototype system whose system functions are created through the integration of services in GATSF.
A flexible integration framework for a Semantic Geospatial Web application
Ying Yuan, Kun Mei, Fuling Bian
With the growth of the World Wide Web technologies, the access to and use of geospatial information changed in the past decade radically. Previously, the data processed by a GIS as well as its methods had resided locally and contained information that was sufficiently unambiguous in the respective information community. Now, both data and methods may be retrieved and combined from anywhere in the world, escaping their local contexts. The last few years have seen a growing interest in the field of semantic geospatial web. With the development of semantic web technologies, we have seen the possibility of solving the heterogeneity/interoperation problem in the GIS community. The semantic geospatial web application can support a wide variety of tasks including data integration, interoperability, knowledge reuse, spatial reasoning and many others. This paper proposes a flexible framework called GeoSWF (short for Geospatial Semantic Web Framework), which supports the semantic integration of the distributed and heterogeneous geospatial information resources and also supports the semantic query and spatial relationship reasoning. We design the architecture of GeoSWF by extending the MVC Pattern. The GeoSWF use the geo-2007.owl proposed by W3C as the reference ontology of the geospatial information and design different application ontologies according to the situation of heterogeneous geospatial information resources. A Geospatial Ontology Creating Algorithm (GOCA) is designed for convert the geospatial information to the ontology instances represented by RDF/OWL. On the top of these ontology instances, the GeoSWF carry out the semantic reasoning by the rule set stored in the knowledge base to generate new system query. The query result will be ranking by ordering the Euclidean distance of each ontology instances. At last, the paper gives the conclusion and future work.
Discussion on remote sensing information processing service based on uniform semantic model
Haigang Sui, Qian Li, Qin Zhan, et al.
With the rapid increase of remote-sensing information data, remote-sensing information processing becomes more important and complicated. However, the processing methods used lead to low processing speed, and make it difficult to realize resource sharing and mutual operation. Web Services technology can promote research into rapid processing and share of the remote-sensing data in a heterogeneous environment, so it can help to solve this problem. The existing problem is that descriptions of the service lack of well-defined semantic information and reasoning ability, so the computer can't understand the rich information from the network. Based on the situation mentioned above, this article puts forward a uniform semantic model to solve this kind of problem.
The construction of CNL rules in mobile GIS
Ling Zhang, Yi Long, Yue Chen, et al.
Natural language has been considered as one of the most habitual and effective ways of human-computer interaction (HCI). This paper proposes the constrained principles in the perspective of mobile GIS nature language, and it also restricts understanding of natural language in the domain of the specific application in mobile GIS. For implementing the interaction between mobile GIS and users with nature language, we should establish the grammar rules and the understanding method of these rules in the view of system control and spatial information inquiry. We use speech technology and mobile GIS to carry human-computer interaction out in order to achieve a friendlier, more intelligent, and easier operated way for the visit of user and the expression of information. It can promote mobile GIS to a state which is more intelligent and socialized and also improve its degree of practicality.
Research on a Chinese word segmentation method based on spatial information query of GIS
Yao Pang, Yi Long, Chen-yang Qian, et al.
Spatial information query is one of the most fundamental applications in GIS. Spatial information query based on Chinese means making a query in forms of Chinese language. Word segmentation is the first step in the process of query understanding. With the help of related searching method to extract the characteristic words from the input sentence, we can segment it into several parts for further analyzing, and then map them to a subset of spatial information database and feed back the result to the user. This thesis tries to improve the study of Chinese spatial information query and proposes a word segmentation method based on a set of characteristic words. The method rearranges the query sentence according to the given patterns and abandons the irrelevant words. Moreover, when meeting the wrong object names or unknown ones, it will amend or insert them into the dynamic library automatically. Such word segmentation method not only takes away the identification of irrelevant words but improves its efficiency of spatial information query and makes for the following mapping to the spatial database.
The application study of OWL reasoning based on ontology for digital urban planning
Jing Luo, Anrong Dang, Qizhi Mao
The rising of semantic Web technology has advanced the development of ontology technology. Ontology as the foundation of semantic Web has exerted many significant role in knowledge expression and knowledge reasoning. After introducing OWL language, ontology and ontology reasoning, this paper constructed spatial ontology in digital urban planning and ontology reasoning system based on OWL then has finished relative reasoning experiment through applying this system. The experiment result indicated that spatial ontology that based on OWL not only extended the relations between classes and attributes, also improved the capability of inquire and reasoning.
The semantic parsing for GML based on SIDB
DongLai Jiao, ShuLiang Zhang, GuoNian Lv, et al.
GML data is widely used for model building, data exchanging, etc. The GML data parsing is the base of handling other operation of GML. The parsing technology of XML can be used for GML parsing. But the XML parsing technology is deficient in parsing semantic information on geography information. This paper tries to build a semantic information database (SIDB) of GML and design GML core schema-based parsing engine which based on SIDB. Ultimately actualize GML data parsing. The results of the study are verified by GML test data in the paper. And more, this study provides a new way to parsing semantic information in other fields.
Semantic expressions of geographical ontology in the city reference frame model
Hengcai Zhang, Jing Zhang, Wenqian Chen
Spatial relations are the foundation of spatial analysis which has important roles in GIS. A reasonable coordinate frame model should be able to describe the orientation relations of two geographic objects clearly, which is part of spatial relations. The reference frame model, which is built according to the spatial pattern of city layout and reflects human's geographic cognition, is helpful in qualitative spatial reasoning, geographic semantic expression, and inquiring based on the natural languages. Geographical ontology is about the knowledge and concepts which have in common in the domain of geography. A semantic model based on ontology can describe the connection of two concepts and provide a new way to construct concept models. This paper mainly studied the meaning of geographic concepts based on 12-direction city coordinate frame model of Beijing. The way of exchanging geographic knowledge and geographic semantic expressions are also important parts of this paper. Based on the reference frame model, the paper built a knowledge database of geographic ontology. The spatial and non-spatial knowledge could be expressed and inferred by the database. This research makes full preparation for establishing the LBS service structure supporting natural languages.
Key solutions to geographical information synchronizing in GRID-GIS
Jian Tan, XiangTao Fan, XiaoPing Du
Geographical GRID system is of great importance at fields as public security, military action, emergency response etc. The homogenizing distributed geographic environment system requires same geographical information for operations in each node. The bottle neck is how to reliably and accurately synchronize the great volume geographical data. This paper solves the problem in three ways. First, Message server queue is constructed for stable message delivery. In this way, the message server always has its alternative in preparation for breakdowns, and the whole GRID always has single working message server. Then the message server queue can be constructed and effectively woks. This mode has the advantages of the other two modes that the message delivery is more reliable and less time-costing. Second, both push and pull modes are adopted to send messages in time. Push mode means the node which has altered its data is responsible for the delivery of the changed part, like "push" the data to the message server. While pull mode means the demand node or the message server is responsible to check the data status in other nodes and "pull" the new data from the source. In push mode, if the network between the sponsor node and the message server breakdown, the message could be missing or the sponsor could be halted, when the network resumed, the update action could not be invoked again. And in pull mode, the message server needs to check the data and collect update parts in the whole grid, it is a time-costing operation that could not be executed frequently. So the combination mode is adopted. In combination mode, not only each node has its own update trigger to invoke the delivery of the new data, but also the message server also can recurrently check the data status after an assigned interval according to the network situation and the computation ability, then the duly update can be guaranteed. Three, extended GML is developed to wrap the geographical data. GML defines a lot of types of elements and attributes to describe geographical entity in detail. But to synchronize geo-information in GRID-GIS, these definitions are not adequate. Because the spatial data must be wrapped into small flexible and linkable unit to cut down the time of delivering and receiving which are the most unstable periods in synchronizing course and to resend and assembly the units in unambiguous order. So our system developed the extended GML format, in which granularity level, including relation, inner string length are defined. By its help, the volume of data message is controllable and it is more reliable and accurate to resend and assembly the data fragments. These three methods are the key solutions to the geographical information synchronizing in GRID-GIS. Their validity has proved in practice.
GIS information organization based on the Semantic Geospatial Web
Shuxia Li, Xuming Su, Ke Li
People typically use geographic names instead of coordinates to find geographic information on the web through a search engine. But the current keyword-based web search engines are poorly adapted to help people find information that relates to a particular geographic name, because they don't incorporate the geospatial semantic during the search process. The Semantic Web is a new semantic-based information-retrieval environment. We propose the information organization framework of the GIS semantic data according to the architecture of the Semantic Web, that is, the ontology, the metadata and the data source. Then we deal with the organization of the semantic data based on the three-layered framework respectively. As a focus, we present a novel method to disambiguate geographical name based on the ontology of the place.
A spatial query scheduler in a distributed environment
Chunhui Zhou, Xinyan Zhu, Yu Xia, et al.
Geographic Information System (GIS) is moving towards distribution and sharing. Distributed Spatial Database Systems (DSDBS) has attracted the attention of many scholars. This paper introduces the prospects of Distributed GIS (DGIS), and describes the definition of DSDBS and the existing problems. The researches in related fields are analyzed, including the research results in the traditional distributed relational database fields, the distributed spatial database fields and the spatial query optimization aspect. Grid technologies are developing forward, and grid will be turned into the standard distributed computing platform, therefore the application of DSDBS will be much broader than ever. The present studies on distributed spatial query focus on spatial join optimization. Researches on query scheduling are rare. In the process of constructing our test system for distributed spatial query, we find there are some replication nodes after the step of data localization. These nodes cause redundant computing of query processing. This paper gives a method to solve it based on the Query Scheduling Tree Model (QSTM). It also gives a detailed scheduling algorithm, and analyzes the effectiveness of the model and the algorithm.
Spatial grid services for adaptive spatial query optimization
Bingbo Gao, Chuanjie Xie, Wentao Sheng
Spatial information sharing and integration has now become an important issue of Geographical Information Science (GIS). Web Service technologies provide a easy and standard way to share spatial resources over network, and grid technologies which aim at sharing resources such as data, storage, and computational powers can help the sharing go deeper. However, the dynamic characteristic of grid brings complexity to spatial query optimization which is more stressed in GIS domain because spatial operations are both CPU intensive and data intensive. To address this problem, a new grid framework is employed to provide standard spatial services which can also manage and report their state information to the coordinator which is responsible for distributed spatial query optimization.
Multilingual mapping based on XML-SVG
Yan Li, Michael P. Peterson, Haosheng Huang, et al.
With the development of geo-informatics, the demands of web mapping services are increasing worldwide. However, these services need to be more accessible and personalized including the ability to display multiple languages in a single interface or a geo-spatial Web Site in terms of 'on-the-fly' map representation and decoration for international visitors. This paper is proposed a multilingual-based approach which a SVG based map is the primary source for preparing a multilingual Web map. According to the basic concepts or principles of map decoration, the paper gives not only an ontological model of map representation and decoration but also indicates clearly that the general issues and main theories and methods of multilingual text on Web mapping. Then, it combines different techniques to decorate the Web map such as SVG specification, four color theorem and line simplification. In order to handle the concurrent hierarchies in geometric context of the map, a geometric view of the solution, a segment tree structure and range-query structure were adapted to solve the issues of text kerning along the curve and multilingual text overlap on one point or coordinate in particular multidimensional or multi-element ones. By the experiments, this approach can be used to implement the spatial query like accessing spatial geometric elements and attributes and it can also be creating maps on-the-fly for multilingual map generalization and integration. Finally, these approaches were implemented and supported to create a software platform called 'Spatial Information Service System' which focus on the integration with multiply sources of spatial information as a disseminating and serving platform for visualizing functionality and generating maps on-the-fly in the context of web mapping applications.
Formal representation of geographic ontology and its application in map services
Geographic ontology is a very complex and intricate concept. As a philosophical concept, ontology has the most ambiguous meanings. In the paper, firstly the concept of geographic ontology is explored and the three meanings of geographic ontology are put forward: philosophy ontology, information ontology and spatial ontology. Then it introduces some ontology representation languages and concludes by suggesting OWL as the appropriate language for building geographic ontology. But geographic ontology is quite distinct from the general information ontology in that it should represent spatial properties as well as attribute properties. Unfortunately, OWL cannot describe spatial properties and spatial relations of geographic ontology because they are mainly for representing the general information ontology. It puts forward to build some formal axioms about spatial properties of geographic ontology by use of three theoretical tools: mereology, location theory and topology. With these axioms, we can formally represent geographic ontology with spatial properties. Finally, it shows how we can use geographic ontology to describe map services and to improve the quality of map services.
A study on ontology-driven geospatial-information retrieving in the Semantic Web
Quan-Li Xu, Kun Yang, Jun Wang, et al.
Firstly, this paper expounded that the traditional searching based on keywords has a severe deficiency on Recall and Precision because the computer can't understand what information mean efficiently. In Succession, through extending from ordinary information to Geo-spatial information, on the support of geo-ontology theory and semantic web services technology, this paper discussed the principle, methods and application of ontology-driven geo-spatial information retrieving mechanism in semantic web. In other word, How to structure the framework for running this mechanism, how to build the ontology information models and how to establish the ontology-driven services models are discussed in detail in context. A design of systems for implementing the mechanism and experiment are given at the end of the text.
A study on heterogeneous distributed spatial information platform based on semantic Web services
Shuang-yun Peng, Kun Yang, Quan-li Xu, et al.
With the development of Semantic Web technology, the spatial information service based on ontology is an effective way for sharing and interoperation of heterogeneous information resources in the distributed network environment. This paper discusses spatial information sharing and interoperability in the Semantic Web Services architecture. Through using Ontology record spatial information in sharing knowledge system, explicit and formalization expresses the default and the concealment semantic information. It provides the prerequisite for spatial information sharing and interoperability; Through Semantic Web Services technology parses Ontology and intelligent buildings services under network environment, form a network of services. In order to realize the practical applications of spatial information sharing and interoperation in different brunches of CDC system, a prototype system for HIV/AIDS information sharing based on geo-ontology has also been developed by using the methods described above.
A storing approach for spatial visualizing database based on XML-SVG
Xuemin Dong, Yan Li, Haosheng Huang, et al.
As a network standard of graphic visualization, SVG (Scalable Vector Graphics) faces an uncompleted representation of spatial information such as spatial position, spatial relations and map symbols and map decoration. And it's either impossible to avoid a great capacity of spatial data processing which slowed down the executing speed of the system on client side. Thus, a SVG-based visualizing database has been proposed as the solution for managing all the graphics and its attributes of SVG document in a DBMS for Web GIS. The experimental results of the solution shown, 1) it improves the efficiency of visualizing data transforming and displaying and saves at least half of the implementing time; 2) it provides an operation in element level based on the designed database structure by selecting the medium granularity as a storing node; 3) the storing scheme can hold the characteristics of spatial information including spatial position, spatial relations and map symbols and map decoration by the comparison of both data in document and in the database; 4) it showed an advantage of the interactive operation with connecting multiply scale of data layers; 5) the database can creates an externally stored scheme which makes a directly connection between spatial graphic object and joining attribute database.
Geo-simulation
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Simulation of the change of regional ecosystem services value based on CA-Markov
Qiuji Chen, Wanqiang Yao
During the last few years, the value of ecosystem services, the possibilities and rationalities of evaluating these services have attracted interests of many ecologists and economists. However, the dynamic change of ecosystem services is less studied. In this paper, the dynamic simulation method (i.e., CA-Markov) is used to simulate the change of ecosystem services value in research area. The main objective of this study is to give comprehensive and reasonable assessment of the ecosystem services value change in the research area which would provide scientific basis for environment, ecosystem construction and strategic decisions. Based on the remote sensing dada of year 1992 and 2003, the landscape information of research area is obtained, and the transfer matrix among various landscapes is calculated during the period, then the data of landscape of research area in year 2015 is predicted using the model of CA-Markov. Then the change of ecosystem services value is calculated based on the value coefficient of various landscapes. The research demonstrates that the CA-Markov is a good tool for simulating the change of ecosystem services value. The studied result can provide scientific basis for ecosystem construction and strategic decisions.
Surface water hydrologic simulation of Qingshuijiang Watershed based on SRTM DEM
Congguo Tang, Congqiang Liu
The Digital Elevation Model (DEM) derived from NASA's Shuttle Radar Topography Mission is the most accurate nearglobal elevation model that is publicly available. The characteristics, advantages, and disadvantages of Shuttle Radar Topography Mission (SRTM) data sets were reviewed and discussed briefly. In order to verify the effect of applying SRTM data sets in surface water hydrologic simulation, a tool set named Arc Hydro Tools that is utilized to extract watershed characteristics was introduced, developed as an ArcGIS interface. The Qingshuijiang watershed in Guizhou Province, Southwest China, was taken as a case study. Using the tool set, the river network and subwatersheds of main tributaries were delineated from CGIAR- CSI SRTM 90 m DEM. By comparing the river network delineated from CGIAR-CSI SRTM 90 m DEM with the actual river network and comparing areas of the subwatersheds delineated from CGIAR-CSI SRTM 90 m DEM with the actual areas of the subwatersheds, it can be concluded that the delineated river network is generally in accord with the actual river network, as well as the areas of the delineated subwatersheds. The CGIAR-CSI SRTM 90 m DEM will promote the use of geospatial science and applications for digital topography analysis, especially for surface water hydrologic simulation.
Coupling multi-agent model and GIS to simulate pine wood nematode disease spread in ZheJiang Province, China
Huaguo Huang, Lei Wang, XiaoLi Zhang, et al.
A coupled method based on multi-agent model, remote sensing and GIS is described to simulate the forest disease spread. The coupled model focuses on the temporal dynamics of the Bursaphelenchus xylophilus population at the landscape scale. Each individual is modeled as an autonomous agent who behaves according to a set of rules including spreading in the landscape, feeding on Pinus massoniana, sheltering in forest edges and dying, constrained by terrain, land cover and other variables. The model parameters are derived from remote sensing data and field measurements. Ten factors, including damage degree of Pinus Massoniana, altitude and slope, are helped to build the transfer rules. The main outputs are the dynamic disease distribution maps and survived pine population. Our method is applied and validated in DingHai distinct, Zhou Shan city of Zhejiang Province. Three Landsat TM images from the year 1991 to 2006 are used for the pine information extraction. The extracted pine distribution map is used to compare with the simulated surviving pine map. The results show that the coupled model can produce reasonable results and be used as a virtual experiment tool. However, it is difficult to simulate the human activities to help or prevent disease spread and the long fly behavior of insect vectors. Therefore, there still exists some difference between the simulated results and the real data. At the next step, those factors will be considered.
Spatial and temporal dynamic of urban sprawl in West China: a case study of Chongqing, China
Fengyun Mu, Zengxiang Zhang, Bin Liu, et al.
Based on eight remotely sensed images, this paper studies the spatial-temporal characteristic of Chongqing's city spatial morphology evolution in recent three decades. The process and characteristics of urban expansion and urban morphology are analyzed using fractal dimension, radiation index and compactness index based spatial morhoplogic measurement coupled with land use change mornitoring. The results show that Chongqing developed by leaps and bounds and experienced three major stages, i.e., relatively stable period in the 1980s, the slow development period after the mid-1980s and the relatively high-speed development period in recent years. The urban built-up area was 87.32km2 in 1978 and increased to 282.91km2 in 2005. The increase built-up area originagtes from different land use type, of which about 76.86% coverted from arable land and about 20.52% coverted from rural area and dependent factory, diggings land and other construction area.
Swarm intelligence and spatial information process
Xiaosan Ge, Xuehua Zhu, Keke Xu
Following the development of spatial data collection technologies, more and more spatial data have been collected through various ways. Increasing demands are being put forward on use of spatial data in many aspects such as spatial data analysis, spatial data mining and knowledge discovery. Swarm intelligence is one of the most known examples in different manners, which offers an alternative way for spatial information process. This paper intends to focus on this new approach in spatial information process by using swarm intelligence. We first study the mechanism of this issue from a new point view, then the advantages of this advanced technology in spatial information process is discussed, and the research status in the field of spatial information process is studied. Last we presented applied Nature Inspired System for the future intelligent spatial information process.
An improved cellular automata forecasting model for urban land use spatial structure changes
Yan Wang, Peilin Wu, Zhenbai Song, et al.
Though the urban land use spatial dynamic simulation and forecasting based on cellular automata (CA) model have achieved remarkable progress, the CA model still has some problems and drawbacks in forecasting urban land use changes. In view of the deficiencies of traditional urban CA, an improved CA model based on spatial dynamic data mining and random forecast is proposed in this paper, which establishes an operable CA method to forecast and simulate the discrete status attribute. This improved CA model is examined in analyzing the urban land use structure changes in Jinan 2002-2006 and testified both feasible and effective. Based on the remote sensing images in Jinan 2002 and 2006, the urban land use spatial structures are classified into five types, commercial land, residential land, education facility, industrial land and the other. With the improved CA model, the urban land use framework in Jinan in 2010 was calculated, the result of which can be used as a reliable reference information for the following urban land use planning.
GIS-based visual simulation of the underground transformer substation construction
Wen-peng Dong, He-hua Zhu, Xiao-jun Li
By use of 3D dynamic visual simulation technology based on GIS, this paper puts forward a suit of construction system of 3D visual digital modal and construction process simulation methods for pit foundation. Graphical modeling and dynamic simulation of the entire construction process visualization was realized. At first, the 3D geologic strata model is realized according to pre-results of our research group, the 3D visual digital model construction method and corresponding standard database establishment are discussed, and then according to the relational database, the whole up-down construction method of pit foundation construction process dynamic simulation path is set up. The graphical modeling facilitates the establishment of simulation model by combining graphic model elements based on hierarchical modular modeling theory. The entire process uses discrete event system simulation basic concept, adjusts to use relational database, and carries out construction model combination. Combining the whole and detail simulation states, the paper carries out the entire dynamic construction progress simulation, and at last develops a large 3D visual simulation system of pit foundation based on the World Expo 500kV transformer substation pit foundation of Shanghai World Exhibition.
Effect of land use change on storm runoff simulation using a simple distributed hydrological model
Xianghu Li, Liliang Ren, Bang Yang
Land-use change is the most remarkable symbol of the earth landscape evolution, also one of the main factors which accelerate regional and even global change. The impact of land-use change on storm runoff is a hot topic in hydrologic research and is often assessed by hydrological model through designed land-use scenarios. In this study, a simple distributed hydrological model is introduced and improved to make model scheme more close to the practical processes and integrate with more remote sensing data. The improved model is tested with six representative and isolated storm events and gained a good performance. All the relative errors of storm runoff depth are less than 18% and the peak discharge errors are within 20%. Although the flood peak of all storm take place one or two hours in advance, but the Nash efficiency are approving, not less than 81%. The investigation of land-use change effect through 4 designed landuse scenarios reveal that land cover with forest corresponds to large interception and woody savanna corresponds to small interception. The croplands have almost the same interception as in actual land-use. Runoff depth decreases in forest land and increases in woody savannas and croplands. Peak discharges have the same variation as runoff depth. Croplands make peak discharge increase more than 20%, at the same time, return period of flood become shorten. However, the time to flood peak are changeless in every land-use scenarios due to the small study area probably.
Quantitative analysis of scale sensitivity in geographic cellular automata
Honghui Zhang, Yongnian Zeng, Changlin Yin, et al.
Geographical Cellular Automata (GCA) approach is based on complexity theory and is widely used in geospatial modeling. A reason for the increasing attention given to GCA models is that they can easily be integrated with rasterbased GIS environment. However, the behavior of the GCA models is affected by uncertainties arising from the interaction between model elements, structures, and the quality of data sources used as model input. The objective of this study is to examine the impacts of model elements on the generated outputs of a GIS-based GCA land-use growth model using sensitivity analysis (SA) approach. The proposed SA method consists of KAPPA index with different spatial metrics. A stochastic GCA model was built to model land use change in the changsha region (Hunan,China). The transition rules were empirically derived from four Landsat-TM (30m resolution) images taken in 1996,1999, 2002 and 2005 that have been resampled to four resolutions (30, 60, 90, 120m). Five different neighbourhood configurations were considered (Moore, Von Neumann, and circular approximations of 2, 3 and 4 cell radii). Simulations were performed for each of the twenty spatial scale scenarios. Results show that spatial scale has a considerable impact on simulation dynamics in terms of both land use area and spatial structure. The spatial scale domains present in the results reveal the nonlinear relationships that link the spatial scale components to the simulation results.
Simulation of urban growth using a cellular automata-based model in a developing nation's region
Changlin Yin, Dingquan Yu, Honghui Zhang, et al.
Cellular automata (CA) modeling is one of the recent advances in spatial-temporal modeling techniques to the field of urban growth dynamics. A number of CA-based models of urban growth have produced satisfactory simulations of spatial urban expansion over time. The paper explained the parameters, transformation and calibration of the SLEUTH model-one specific format of the cellular automation model, on the base of which the process of urban growth of changsha city between the year 1996 and 2005 is rebuilt. Moreover the spatial morphology of Changsha city in 2015 and 2030 is separately predicted with the method of scenario simulation. The results of analysis and simulations indicate that application of the SLEUTH model to simulation of urban growth is advisable and the accuracy of simulation is acceptable.
Integrating GIS and urban spatial system dynamic model for urban expansion analysis
Hongmei Ye, Lijun Li, Cheng Wang, et al.
Urban evolution model is an assistant analysis method for urban planning which can effectively trace the urban development process of the past and predict the possible evolution scenarios in the future. This paper proposed urban spatial system dynamic model (USSD model) by coupling strategy between Geographic Information System (GIS) and urban System Dynamic (SD). GIS can deal with the static spatial relationships while SD can deal with the dynamic relationships of complex spatial system. This new urban expansion model can predict the expansion scenarios in the future according to tracing the urban development of the past. It considered the spatial relationships among urban system elements as well as the dynamic links and interactions among the spatial elements over time. It is achieved through a dynamic data exchange between GIS and SD. Firstly we analyzed urban system by using five subsystems: population, resources, transportation, land usage and soil erosion. Secondly, we have developed USSD model based on dynamic links among the subsystems. Thirdly, we have created five layers in GIS and operated them in the USSD model. Finally, a case study illustrated the USSD model in Wuhan city. It is concluded that the USSD model is an efficient tool for forecasting the urban expansion with its advantages on dealing with the spatio-temporal problem.
Research on optimal allocation model of land resource based on niche and CA
Han-hua Wang, Yan-fang Liu
Land resource optimal allocation has always been one of the most challenging issues in land science field. The classical methodologies and theories of land resource allocation optimization pay more attention to the economic benefit and ignore the environmental benefit and the ecological benefit, Which has breached the sustainable development; moreover, it devote more attention to the amount structure optimization and ignore the spatial configuration optimization. In recent years, Many researchers bring forward some integrated models, Which realized the social, ecological and economic benefit. But nearly nobody can construct the integrated model which could combine the amount structure optimization with the spatial configuration optimization. This article use niche model to optimize the land amount structure and simulate the spatial configuration based on CA.
Dynamic simulation of ground deformation based on animation
Zhijie Wang, Jiazhu Zheng, Liheng He, et al.
Ground deformation caused by groundwater exploitation, mine exploitation, deep foundation pit excavation, etc, seriously threatens normal production and life and structure safety of buildings, and the capacity of soil cultivation descends or abandons, so it is significance that studying defending and controlling methods of ground surface deformation. Because of the difficulty of reality expressing spatio-temporal characteristic and information of ground surface deformation, in order to solving the problem, it is need to adopt combining methods both spatial information technology and animation technology, and discusses the contents and ways of ground surface deformation dynamic simulation. Firstly, by means of ground surface deformation spatio-temporal course, the ground surface deformation spatio-temporal is founded. Secondly, on the basis of analyzing the time effect and space distribution characteristics of ground surface deformation caused by groundwater exploitation, mine exploitation, deep foundation pit excavation, the contents and ways of ground surface deformation dynamic simulation is founded. Finally, spatio-temporal characteristic of ground surface deformation is simulated by animation technology, digital terrain model and spatio-temporal database. The research shows that the dynamic simulation can nicely reflect spatio-temporal characteristics of ground surface deformation, and can expediently and rapidly study the laws of ground surface deformation. Keywords: animation, ground deformation, dynamic simulation
DSM generation from multiple digital aerial images in urban area
In this paper, we present a matching method for DSM generation from multiple images based on feature points, which introduce the coarse-to-fine strategy, geometrically constrained matching and relaxation technology, the matching is guided by the information in the object and make full use of the information in both image and object space. A match appearing in any pair has the chance to survive, and very dense disparity maps are obtained. Experiments have been performed and the height accuracy of the derived DSM is about 3 pixels.
Multi-agent simulation of the von Thünen model formation mechanism
Haiyan Tao, Xia Li, Xiaoxiang Chen, et al.
This research tries to explain the internal driving forces of circular structure formation in urban geography via the simulation of interaction between individual behavior and market. On the premise of single city center, unchanged scale merit and complete competition, enterprise migration theory as well, an R-D algorithm, that has agents searched the best behavior rules in some given locations, is introduced with agent-based modeling technique. The experiment conducts a simulation on Swarm platform, whose result reflects and replays the formation process of Von Thünen circular structure. Introducing and considering some heterogeneous factors, such as traffic roads, the research verifies several landuse models and discusses the self-adjustment function of price mechanism.
Modeling urban land use changes in Lanzhou based on artificial neural network and cellular automata
Xibao Xu, Jianming Zhang, Xiaojian Zhou
This paper presented a model to simulate urban land use changes based on artificial neural network (ANN) and cellular automata (CA). The model was scaled down at the intra-urban level with subtle land use categorization, developed with Matlab 7.2 and loosely coupled with GIS. Urban land use system is a very complicated non-linear social system influenced by many factors. In this paper, four aspects of a totality 17 factors, including physical, social-economic, neighborhoods and policy, were considered synthetically. ANN was proposed as a solution of CA model calibration through its training to acquire the multitudinous parameters as a substitute for the complex transition rules. A stochastic perturbation parameter v was added into the model, and five different scenarios with different values of v and the threshold were designed for simulations and predictions to explore their effects on urban land use changes. Simulations of 2005 and predictions of 2015 under the five different scenarios were made and evaluated. Finally, the advantages and disadvantages of the model were discussed.
The animation of tree development based on timed L-systems
Yue Zheng, Lixin Zhang
In the area of forest RADAR remote sensing, L-system is often used to obtain realistic tree structures and the components. With the development of knowledge and computer graphics, static tree models simulated by computers are animated. Timed L-systems and tree growth functions are introduced to model and visualize the growth of those static tree models we developed before.
Research on urban sprawl based on GIS and CA
Fen Qin, Lijie Yan
The complex urban system can't be simulated directly by the traditional and static models. Cellular automata (CA) is a kind of dynamically modeling framework from bottom to top, which possesses the capability of modeling spatialtemporal evolvement process of a complicated geographical system. The peculiarities of CA are apt for simulating urban sprawl, urban expansion and land use evolution, which make the application of CA become very popular. The environment of CA simulation can be improved by using the CA model integrated with GIS to simulate the urban sprawl, and new parameters and transition rules can be found out by establishing classical urban CA. The paper summarizes the status and the application of urban CA in the world, develops a CA model named GIS-CA on the basis of the principle of CA, integrated with GIS and RS, adds urban plan as controlling factor into GIS-CA model, and uses GIS-CA model to simulate and forecast urban sprawl, and takes Luoyang City as the case study. The simulation and forecast results are acceptable for that the precision and Lee-Sallee shape index are rational.
BUDEM: an urban growth simulation model using CA for Beijing metropolitan area
Ying Long, Zhenjiang Shen, Liqun Du, et al.
It is in great need of identifying the future urban form of Beijing, which faces challenges of rapid growth in urban development projects implemented in Beijing. We develop Beijing Urban Developing Model (BUDEM in short) to support urban planning and corresponding policies evaluation. BUDEM is the spatio-temporal dynamic model for simulating urban growth in Beijing metropolitan area, using cellular automata (CA) and Multi-agent system (MAS) approaches. In this phase, the computer simulation using CA in Beijing metropolitan area is conducted, which attempts to provide a premise of urban activities including different kinds of urban development projects for industrial plants, shopping facilities, houses. In the paper, concept model of BUDEM is introduced, which is established basing on prevalent urban growth theories. The method integrating logistic regression and MonoLoop is used to retrieve weights in the transition rule by MCE. After model sensibility analysis, we apply BUDEM into three aspects of urban planning practices: (1) Identifying urban growth mechanism in various historical phases since 1986; (2) Identifying urban growth policies needed to implement desired urban form (BEIJING2020), namely planned urban form; (3) Simulating urban growth scenarios of 2049 (BEIJING2049) basing on the urban form and parameter set of BEIJING2020.
Simulation of waste gas pollution diffusion for urban planning: take Nanjing as an example
Junting Chen, Jianggang Xu, Yi Qi, et al.
Waste gas pollution diffusion is one of the basic factors that should be considered in the layout of urban planning. In the field of Chinese urban planning, limited by the planning skill and the level of different departments' involvement, the future pollution degree and pollution range of industrial region is hard to be predicted accurately. The newly issued Urban and Rural Planning Act carry out scientific development idea, pay more attention to the proteaction of urban ecological environment in principles, and encourage the application of new technology and new methods in planning skill. This paper combines digital map information, collects industrial point source spatial data of Nanjing, selects appropriate model from the technical requirements of urban land planning, establish database of air pollution diffusion based on ArcGIS platform, calculates spatial concentration of air pollution diffusion with interpolation, and carry out superposition between 16 wind directions and value in multi-sources air pollution, puts forward the conception of effective pollution range according to national environment management system standard, and performs a preliminary spatial fitting between computing result of spatial data and urban land, evaluates the effects of waste gas pollution in Nanjing on urban land planning. Finally the research direction that can be prolonged is pointed out.
Study of forecast simulation technology of water pollution emergencies based on GIS
Dayong Yang, Kui Lin, Guoqiang Jiang, et al.
The frequent occurrences of major water pollution emergencies in China have aroused the widespread social and governmental concerns. How to address serious water pollution is a complex task with integration of several elements. Focusing on the weakness of the mission, the paper has made comprehensive analysis of the characteristics of various water types, operation status of different pollutions. Study was made on the prediction simulation of unexpected events, and a forecast system of water pollution events was designed and established with the support of the environmental water models. The research in the paper has adapted to the environment management in the new phase and met the urgent demand in the water pollution emergencies; hence it is of practical significance.
Dynamic transition rules for geographical cellular automata
Q. S. Yang, X. Li
There is rapid development of CA models for simulation of land use patterns and urban systems recently. Traditional models use the uniform transition rules in large areas or at long times. These models have limitations because they use the same factors and weights in different places or times while these factors and weights vary spatially. This paper presents the method of using dynamic transition rules for producing more reliable urban simulation. The advantages of dynamic transition rules are apparent in this paper. First, it uses different factors and weights in different regions which are consistent with actual urban systems. Second, the main factors can be obtained from the dynamic transition rules in different regions which may produce different urban development patterns. Based on the stepwise logistical regression model, dynamic transition rules were obtained for simulating the evolution of the urban systems in five towns of the Dongguan city from 1988 to 2004. Compared with the general CA model, the simulation precision is improved by using this method. From the factors and weights of dynamic transition rules, three kinds of development patterns were obtained: center development pattern, road development pattern and center-road development pattern.
Fuzzy set theory based model for simulating land use change
Ying Ge, Xinyu Li, Ye Wu, et al.
The land use change is a progressive and non-deterministic process both spatially and temporally. In dealing with this relatively complicated spatial phenomenon, the Fuzzy Set theory could be employed to represent and handle the spatial uncertainty in the two-dimension continuous space. This study thus combines this theory with the shape interpolation technique to simulate the change of land use across space over time. Specifically, the Fuzzy Set theory is used for producing a set of intermediate fuzzy layers of geographic features based on two existing ultimate layers. Here the fuzzy membership functions are constructed by a statistic method related to the theory of probability. With a given space-time resolution, the utilization of shape interpolation is aimed at determining the particular location of a geographic entity. Using Nantong City of Jiangsu Province as a case study, the transition progress from non-urban area to urban area between 2001 and 2006 is empirically implemented. The research results are obtained in accordance the realistic situation of urban growth in Nantong City.
Agent-based modeling and simulation for pedestrian movement behaviors in space: a review of applications and GIS issues
Yuhong Zhou
Agent-based approach has the advantage of supporting researches on local dynamics of pedestrian movement at a fine scale. After discussing the categories of environment and pedestrian behaviors, this paper reviews the recent development of diverse applications of agent-based pedestrian modeling and simulation under the four headings: (1) transportation planning for pedestrian facilities, (2) planning and design of urban space, (3) crowding, evacuation/panic, and disaster management, and (4) commercial activity organization and shopping behavior. The proposed various models and simulation systems in most of the applications are still immature and not suitable for practical decision-making. The last section of the paper discusses the relationship between GIS and agent-based pedestrian models and simulation systems, and stresses the enhancement of such models and simulations by incorporating more spatial query and analysis functionalities of GIS.
GIS-based epidemical disease information visualization
Bisong Hu, Jianhua Gong, Jia Sun, et al.
In recent epidemical researches based on GIS, a great deal of studies focus on the data analysis and result deduction using spatial-temporal analysis, scientific visualization, etc. However, there are rare researches on information visualization of various epidemical diseases. This paper studied information visualization of epidemical disease attributes, distribution, and statistics based on GIS, designed a multi-scale and population-based epidemical spreading model by considering the influence of real geographical and demographic information, and implemented its information visualization. The epidemical influence of population immigration is also considered. This model is based on the traditional SEIRS model, and could be applied to the real epidemical spreading simulation on the basis of real epidemical, geographical, social, and demographic data.
A study on multi-agent spatial database update mechanism based on Wiki idea
Hongxia Cheng, Yongshu Li, Yuejiang Lin
Spatial database update is a matter of urgency, which will become the "bottleneck" to GIS application instead of spatial data production. Hence it has become a focus in GIS research fields. This paper outlines the current spatial database update modes and discusses some related practical issues. In order to shorten spatial database update period and improve the intelligence level of system, an incremental spatial database update mechanism was proposed by using the cooperative work characteristic of Wiki idea and the multi-agent technology in artificial intelligence research field. Emphasis is placed on the construction of spatial database update mechanism. Special resolve method, mechanism elements and data update process are presented in detail. As a practical application, we implement a basic farmland management information system. The results show that this multi-agent spatial database update mechanism based Wiki idea can arouse the interaction of users, shorten the period of spatial data update, improve the use value of data and make the spatial database update more convenient and flexible. So, we suggest that this mechanism can provide reference to help solving the problem of spatial data update.
The simulation of satellite tracking and orbit prediction considering the swaths
Lei Cai, Jianya Gong
A simulation system is developed for satellite tracking and orbit prediction. The program displays the location of Earth satellites and predicts the location of any satellite at any time. And the simulation of satellite tracking and orbit prediction take the swaths into consideration. The orbit prediction model and Two-Line Element (TLE) Sets are present first, and the Simplified General Perturbations Version 4 and Simplified Deep-space Perturbation Version 4 (SGP4/SDP4) orbit propagation algorithms are introduced then. In the end, we introduce how we build our system in detail. In the end we present the comparison of the prediction result between the system of ours and STK's. The result shows that SGP4/SDP4 are efficient and valid in our system.
The application and realization of 3D geosimulation and forecast in the field of bank collapse research based on GIS
With the development of computer science, many kinds of three dimensional software come to the world one after another, and have been applied in many fields, such as PC games, military simulation and geographical information system (GIS) and so on, among which the application of the technique of three dimensional geo-simulation in GIS field has provided new platform, new ideas, and a new significant direction for the development of GIS. This paper is to discuss the methods and realization of three-dimensional(3D) geosimulation in the field of bank collapse based on GIS, with the research of bank collapse as the cut-in point, which is the important direction in the research of geological disasters, and to give 3D simulation result of the reservoir bank, taking the related data in three gorges reservoir area as the example, and at the same time to give the result of 3D simulation about bank collapse forecast, and at last to appraise these results.
Commercial facility site selection simulating based on MAS
Yi Chao, Qingquan Li, Guizhou Zheng
The location of commercial facility decides the benefit of the operator to a large degree. Existing location methods can express the static relationships between site selection result and location factors, but there still are some limites when express the dynamic and uncertain relationship between them. Hence, a dynamic, stochastic and forecastable location model should be built which can introduce the customer's behavior into the model and combine the macro pattern and micro spatial interaction. So the authors proposes Geosim-LM based on MAS. Geosim-LM has 3 kinds of agents, CustAgent, SiteAgent and GovAgent. They represent the customers, commercial fercilities and government. The land type, land price and traffic are the model environment. Then Geosim-LM is applied in the bank branches site evaluation and selection in Liwan district, Guangzhou. In existing bank branches site evaluation, there are 70% consistent in score grade between result of Geosim-LM after 200 round runing and actual rebust location. It proves the model is reliable and feasible. The conclusions can be get from the paper. MAS have advantages in location choice than existed methods. The result of Geosim-LM running can powerfully proves that building location model based on MAS is feasible.
Agent-based modeling to simulate the dengue spread
Chengbin Deng, Haiyan Tao, Zhiwei Ye
In this paper, we introduce a novel method ABM in simulating the unique process for the dengue spread. Dengue is an acute infectious disease with a long history of over 200 years. Unlike the diseases that can be transmitted directly from person to person, dengue spreads through a must vector of mosquitoes. There is still no any special effective medicine and vaccine for dengue up till now. The best way to prevent dengue spread is to take precautions beforehand. Thus, it is crucial to detect and study the dynamic process of dengue spread that closely relates to human-environment interactions where Agent-Based Modeling (ABM) effectively works. The model attempts to simulate the dengue spread in a more realistic way in the bottom-up way, and to overcome the limitation of ABM, namely overlooking the influence of geographic and environmental factors. Considering the influence of environment, Aedes aegypti ecology and other epidemiological characteristics of dengue spread, ABM can be regarded as a useful way to simulate the whole process so as to disclose the essence of the evolution of dengue spread.
Earthquake damage scenario simulation of a water supply system in Taipei
Ji-Hao Lin, Walter W. Chen
Taiwan is located in the Circum-Pacific Belt and at the junction of the Philippine Sea Plate and the Eurasian Plate. The island is squeezed over a long period of time, so the frequency of the occurrence of earthquakes is very high. Changes of terrain due to seismic forces such as fault ruptures and surface uplifts could cause extensive damage to water pipeline networks. The 921 Ji-Ji earthquake was one of the most serious disasters in recent years in Taiwan, and it indeed resulted in the most severe damage of water supply systems. The urban water supply network is very important for municipal water management in Taiwan. If the water supply systems break down, hospitals and fire stations will not have enough water to carry out the rescue work, and the results may worsen the disasters. This study took the water supply system of the West District in Taipei City as an example. First, the metro-Taipei area was split into three hundred and twenty-seven 1 km by 1 km cells. Second, the location of a simulated earthquake was determined. Third, the Peak Ground Acceleration (PGA) value of each cell was calculated by an empirical formula. Fourth, the Repair Rate (RR) of each cell was calculated based on its PGA value. Fifth, using the GIRAFFE software developed by Cornell University, the Monte Carlo simulation method was used to simulate the possible damage to the water supply system. And finally, the EPANET program developed by the US Environmental Protection Agency was applied to compute the distribution of flow volumes and water pressures of the damaged water supply system. Results of the pipeline network under different scenarios of earthquake magnitudes are shown in this study, and they provide an evaluation basis to decision makers to improve the pipeline infrastructures for fire protection after major earthquakes.
Modeling and predicting urban growth pattern of the Tokyo metropolitan area based on cellular automata
Yaolong Zhao, Junsan Zhao, Yuji Murayama
The period of high economic growth in Japan which began in the latter half of the 1950s led to a massive migration of population from rural regions to the Tokyo metropolitan area. This phenomenon brought about rapid urban growth and urban structure changes in this area. Purpose of this study is to establish a constrained CA (Cellular Automata) model with GIS (Geographical Information Systems) to simulate urban growth pattern in the Tokyo metropolitan area towards predicting urban form and landscape for the near future. Urban land-use is classified into multi-categories for interpreting the effect of interaction among land-use categories in the spatial process of urban growth. Driving factors of urban growth pattern, such as land condition, railway network, land-use zoning, random perturbation, and neighborhood interaction and so forth, are explored and integrated into this model. These driving factors are calibrated based on exploratory spatial data analysis (ESDA), spatial statistics, logistic regression, and "trial and error" approach. The simulation is assessed at both macro and micro classification levels in three ways: visual approach; fractal dimension; and spatial metrics. Results indicate that this model provides an effective prototype to simulate and predict urban growth pattern of the Tokyo metropolitan area.
Research on monocentric model of urbanization by agent-based simulation
Ling Xue, Kaizhong Yang
Over the past years, GIS have been widely used for modeling urbanization from a variety of perspectives such as digital terrain representation and overlay analysis using cell-based data platform. Similarly, simulation of urban dynamics has been achieved with the use of Cellular Automata. In contrast to these approaches, agent-based simulation provides a much more powerful set of tools. This allows researchers to set up a counterpart for real environmental and urban systems in computer for experimentation and scenario analysis. This Paper basically reviews the research on the economic mechanism of urbanization and an agent-based monocentric model is setup for further understanding the urbanization process and mechanism in China. We build an endogenous growth model with dynamic interactions between spatial agglomeration and urban development by using agent-based simulation. It simulates the migration decisions of two main types of agents, namely rural and urban households between rural and urban area. The model contains multiple economic interactions that are crucial in understanding urbanization and industrial process in China. These adaptive agents can adjust their supply and demand according to the market situation by a learning algorithm. The simulation result shows this agent-based urban model is able to perform the regeneration and to produce likely-to-occur projections of reality.
Projecting the land use changes in China for the next two decades using a dynamic simulation framework
Qun'ou Jiang, Xiangzheng Deng, Jinyan Zhan, et al.
The purpose of this paper is to illustrate a modelling framework to simulate large-scale land use changes, and its effect on the structural and functional diversity of the ecosystem and social-economy based on the remotely sensed digital images. The improved DLS model is developed with three scenarios in China from 2001 to 2020. The projection results show that obvious land use changes will take place in the forestry area, grassland, cultivated land and unused land. Dramatic changes will appear in Cultivated area in Northeast China, Huang-Huai-Hai plain and Southwest China. The changes of forestry area are characterized by regional diversification. Grassland decreases mainly along the Great Wall of Inner Mongolia and on Tibets Plateau. The newly expanded urban land, comparably smaller, distributes mainly around the old towns or residential centers. There is no obvious change in water area. The unused area shrinks with the expansion of forest and grass area in Western China. Based on this study, the capability of improved DLS modelling framework in projecting the LUCC scenarios was tested successfully, and a conclusion was made that DLS model is an useful model in scenario construction.
Simulation and prediction of engineering deformation through comparisons of time serial and wavelet decomposition
Linyuan Xia, Guoxin Peng, Hui Tian, et al.
Deformation on earth's surface covers crust displacement due to tectonism and land slide or subsidence caused by human activities or natural evolvement. The former is explained by tectonician through geologic investigation and researches. The local creep deformation arisen from engineering activities on earth's surface is complex and is often related with local engineering safety. So this kind of deformation attracts wide attention of many scholars and engineers, and is therefore discussed in this paper in way of simulation and prediction. In our work, we compared Auto Regressive (AR), Moving Average (MA) and ARMA models and used AR model to replace other time serial models based on their equivalence. It is found that AR or ARMA are fit for modeling or prediction, but it is hard to obtain deformation mechanism. Wavelet transform (WT) has shown great potential in information extraction and identification. It is also used as a tool to deal with deformation extraction and analysis in this paper. Tests have shown that it can be applied to distinguish different components from mixed observation serials. It is known that an observed serial in deformation monitoring is composed of sophisticated components and each represents different contents and is attributed to some acting factors. In this research, regional and engineering deformation observation is employed as inputs for wavelet decomposition; contents from different frequency scales are obtained at different layers. Deformation trend and rapid deformation changes are found from this multiple inspection transformation. Practical examples are given to reveal the feasibility of wavelet decomposition as a useful inspection tool for deformation analysis. From these work, we come to see that AR approach of time serial is fit for modeling and prediction, while wavelet transform is more flexible in deep inspection of deformation details and can exhibit subtle variation in observation serials. So some comprehensive comparisons are made in terms of time domain and spectrum domain to summarize merits and demerits of both methods. Practical data from field using some instruments are used for analysis and validation to verify the flexibility of suggested models.
A hydrological model based on cellular automata and Doppler radar
Jicai Dai, Xia Li, Xiaoping Liu
Distributed hydrological model(DHM) has been the key research currently in hydrology integrated with digital elevation model(DEM), geographic information system(GIS) and Remote Sensing(RS). Besides these technologies, this paper proposes a hydrological model by integrating cellular automata (CA) and Doppler radar. CA are a kind of bottom-up approaches and can be used to simulate complex hydrological processes. Doppler radar has provided a key input about the precipitation with high resolution to the river discharge simulation. The proposed model has been applied to the Huang Longdai basin in Guangdong with satisfactory results.
A multi-agent-based approach for simulating epidemic transmission
Tao Liu, Xia Li, Jing Fu, et al.
A new model is proposed based on multi-agent system to simulate spatio-temporal transmission process of infectious diseases. The model consists of four components: attributes definitions, neighborhood, movement rules and state transition rules. The state transition rule is the core of the proposed model. In the model, memory of infection of susceptible agents are embodied, moreover, infection dose decay rate and exponential distance parameters are introduced in transmission process, so that the spatio-temporal effect is explicitly considered.
A method of generating moving objects on the constrained network
Jie Zhang, Linbing Ma
Moving objects databases have become an important research issue in recent years. In case large real data sets acquired by GPS, PDA or other mobile devices are not available, benchmarking requires the generation of artificial data sets following the real-world behavior of spatial objects that change their locations over time. In the field of spatiotemporal databases, a number of publications about the generation of test data are restricted to few papers. However, most of the existing moving-object generators assume a fixed and often unrealistic mobility model and do not consider several important characteristics of the network. In this paper, a new generator is presented to solve these problems. First of all, the network is realistic transportation network of Guangzhou. Second, the observation records of vehicle flow are available. Third, in order to simplify the whole simulation process and to help us visualize the process, this framework is built under .Net development platform of Microsoft and ArcEngine9 environment.
Virtual GIS Environments and Cyber Infrastructure
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Design and implementation on rapid Web publication of massive remote sensing images
Qingquan Tan, Jiantao Bi, Tianhe Chi, et al.
With the progress of researches on the integration of Geographic Information System (GIS) and Remote Sensing (RS), digital earth, and information sharing, to publish RS images on the Internet has become a significant research work. In this study, image pyramid model was introduced, and an efficient algorithm to build image pyramid was presented for convenient data storage and retrieval. In order to improve the efficiency, the process of image cutting and resampling was implemented in the RAM, avoiding the unnecessary I/O operations. The algorithm was implemented by combining Java and C++ languages, ensuring both the processing speed and distributed architecture. And two distributed implementation approaches were proposed, based on B/S and C/S architecture respectively. In the programs, some useful functions, such as data compression, image format conversion, watermarking, and automatic error-correction, were also implemented to facilitate and ensure the web publishing work. Tests of the programs with a global RS image showed that they worked efficiently, robustly, and flexibly under the Internet environment. Also, the programs were endowed with user-friendly graphical interfaces, and easy to use. Therefore the rapid web publication of RS images on the Internet becomes easier to accomplish.
UK utility data integration: overcoming schematic heterogeneity
Anthony R. Beck, Anthony G. Cohn, Michael Sanderson, et al.
In this paper we discuss syntactic, semantic and schematic issues which inhibit the integration of utility data in the UK. We then focus on the techniques employed within the VISTA project to overcome schematic heterogeneity. A Global Schema based architecture has been developed. Although automated approaches to Global Schema definition were attempted the heterogeneities of the sector were too great. Hence, a manual approach to Global Schema definition was employed. The techniques used to define and subsequently map source utility data models to this schema are discussed in detail. In order to ensure a coherent integrated model, sub and cross domain validation issues are then highlighted. Finally the proposed framework and data flow for schematic integration is introduced.
The integration of multi-interactive patterns in virtual geographic environment
Yi Yang, Guonian Lu, Yongning Wen, et al.
Virtual Geographic Environment will be a modeling system supporting geographic analysis and visualization for geographic research on modern distributed, heterogeneous network environments. It allows users at different geographic locations sharing spatial information and interacting with each other via Internet. This paper proposes a new multi pattern interactive architecture for presenting different application patterns. The architecture for the integration of multi interactive patterns is separated into three main function layers: Data Layer, Virtual Geographic Environment Layer, and Application Layer. With the multi pattern interactive architecture, the Virtual Geographic Environment behaves itself with multiple application features, each of which is managed by a uniform object which is named "Entity". The objectoriented conceptual modeling mechanism is presented by "Entity" and the relationship between them. In order to fulfil the various interactive patterns of the Virtual Geographic Environment according to the users' requirements, multiple application aspects are integrated dynamically, such as Geo-spatial data sharing, Geographic model integration, twodimensional map, three-dimensional simulation and so on.
The quality-aware GIS supported by a Web based geocomputational tool
Fei Wang
Spatial data quality issues have been put in high priority in GIS community as the increasing share and use of geospatial data, especially when Internet technology became the new medium for delivering digital data to its large audience. However, the current lack of error-sensitive functionality has been exposed and found in many GI systems. Thus, to enhance current GIS with quality aware functions and provide users with the geospatial data of adequate quality becomes a big challenge. This paper focuses on improving and supporting the spatial data integrity in field based Mobile GIS. It examines current approaches of ensuring spatial data integrity and proposes a rule-based means for specifying data integrity requirements. Then the quality-aware GIS concept is introduced, and based on that, a geocomputational tool prototype for interpreting integrity rules and performing the error checking in Mobile GIS is developed. Its functionality corresponding to the detailed field data capture scenarios is introduced. This geocomputational tool has a generic architecture, and it is implemented as the extended geospatial web functions to enhance standardized geospatial web services (OGC WFS). Therefore it can also be easily employed by other different quality-aware GIS applications such as data reprocessing, data analyzing and so forth.
Virtual Global: a new visualization system for virtual geographic environment
Jingwei Shen, Yongjun Wang, Hong Tao, et al.
Virtual Global, a new visualization system is designed and developed by Key Laboratory of Virtual Geographic Environment (Nanjing Normal University) as the visualization platform of the virtual geographic environment. In order to represent various types of data about geographic information, 3D scene, geographic models and geographic phenomena simulation in the world wide, Virtual Global is designed in which terrain, imagery data, various types of 3D models and annotation can be represented. Distributed data service and the transfers of compressed data on the internet are supported, too. The high speed transmission of imagery data, large scale terrain real-time roaming, automatic annotation placement and so forth are also implemented. The spatial scattered grid which can satisfy the modeling and simulating of the geography effectively is integrated into this system. Distributed data management is used and massive data is stored on different computer. Progressive data transmission is introduced and data is downloaded according to the requirement of the client. The frequency of access to the internet is reduced.
Distributed WebGIS model based on server farm
Ying Huang, Zhong Xie, Ming-qiang Guo
The deficiencies of traditional WebGIS model were analyzed. From the points of load-balancing and map status synchronization, we proposed a new distributed model based on server farm. It used user-defined bottom interactive protocol, distributed dynamic balancing scheduling algorithm and map status object pool to solve many problems in the traditional model such as inefficient heterogeneous compatibility, weak parallel processing capability, and the difficulties in map status synchronization. A test-bed was established to verify the performance of the model. A series of test results has proved that the new WebGIS model has strong heterogeneous compatibility, parallel processing capability and faulttolerant features. Through the mechanism of map status synchronization, the new model can realize sustained preservation and synchronization of map operated statuses and meets the demands of users' uninterrupted accesses.
The research and application of network publish automation key technologies based on ArcIMS
Yongjin Xu, Yongzhong Tian, Yanghua Gao, et al.
The development of WebGIS and its widely application provide a good technical support for the network map publishing. This article mainly researched the command of ArcIMS's ADMINCMD, and executed command management to the ArcIMS server with ArcXML technology. In this technical foundation, an automation publishing system based on ArcIMS server has been designed. It gives an example of application combined the Chongqing climate resources management information system.
Grid based model computation of virtual geographic environment: application in Pearl River Delta air pollution visualization
Bingli Xu, Hui Lin, Jun Zhu, et al.
Virtual Geographic Environment (VGE) is a virtual representation of the physical world, culture world and imaginary world. Compared with GIS, VGE has two core components, which are Data and Model respectively. Many models in VGE are complex and therefore the model calculations for them are very time consuming as well. How to decrease and reduce the required model computation time to improve VGE efficiency will be a vital and key issue for most of the VGE implementation. In this research, we adopt CUGrid as the model computation server, which contains more than two hundred CPUs for fast and intensive computation. With the CUGrid, MM5 based air pollution data in Pearl River Delta is used as the test case for this study. According to the test results, we managed to reduce the required model computation time from the original three months on one specific desktop to several minutes on the CUGrid. Another significance and benefit of this research is that we also able to integrate MM5 with geographic information, which makes concepts on air pollution can easily be understood by the public.
The research of WebGIS based on portal
Lei Shen, Weixi Duan, Yingchao Ren, et al.
With the rapid development of computer network technologies and distributed computing technologies, more and more enterprises begin to accept and use Web GIS. As a result of the thought that traditional Web GIS has focused on system, a number of existing Web GIS are isolated by each other, and facing the problems with data islands and function overlaps, which results in the waste of spatial data resources, the redundant construction of spatial information service, the difficulty of system integration and so on. All of these demands that the new generation Web GIS should focus on users, be service-oriented and be easily integrated systems. The introduction of Portal can solve difficulties above. This paper studies how to bring in Portal in the process of designing and developing Web GIS to solve the difficulties of resource integration and the personalized services of users. And the author has successfully implemented a Web GIS Portal based on JSR 168 Java Portlet Specification. The facts have proved that a Web GIS developed by Portal can provide users with better user experience and be easily integrated with other application systems.
Semantic integration for mapping the underworld
Gaihua Fu, Anthony G. Cohn
Utility infrastructure is vital to the daily life of modern society. As the vast majority of urban utility assets are buried underneath public roads, the need to install/repair utility assets often requires opening ground with busy traffic. Unfortunately, at present most excavation works are carried out without knowing exactly what is where, which causes far more street breakings than necessary. This research studies how maximum benefit can be gained from the existing knowledge of buried assets. The key challenge here is that utility data is heterogeneous, which arises due to different domain perceptions and varying data modelling practices. This research investigates factors which prevent utility knowledge from being fully exploited and suggests that integration techniques can be applied for reconciling semantic heterogeneity within the utility domain. In this paper we discuss the feasibility of a common utility ontology to describe underground assets, and present techniques for constructing a basic utility ontology in the form of a thesaurus. The paper also demonstrates how the utility thesaurus developed is employed as a shared ontology for mapping utility data. Experiments have been performed to evaluate the techniques proposed, and feedback from industrial partners is encouraging and shows that techniques work effectively with real world utility data.
An intelligent method for geographic Web search
Kun Mei, Ying Yuan
While the electronically available information in the World-Wide Web is explosively growing and thus increasing, the difficulty to find relevant information is also increasing for search engine user. In this paper we discuss how to constrain web queries geographically. A number of search queries are associated with geographical locations, either explicitly or implicitly. Accurately and effectively detecting the locations where search queries are truly about has huge potential impact on increasing search relevance, bringing better targeted search results, and improving search user satisfaction. Our approach focus on both in the way geographic information is extracted from the web and, as far as we can tell, in the way it is integrated into query processing. This paper gives an overview of a spatially aware search engine for semantic querying of web document. It also illustrates algorithms for extracting location from web documents and query requests using the location ontologies to encode and reason about formal semantics of geographic web search. Based on a real-world scenario of tourism guide search, the application of our approach shows that the geographic information retrieval can be efficiently supported.
Visualization of NASA Earth science data in Google Earth
Aijun Chen, Gregory Leptoukh, Steven Kempler, et al.
Google Earth, as one of most popular geospatial data visualization environment, has been used to augment the research value of Earth science data at NASA Goddard Earth Science Data and Information Service Center. The solutions of how to use Google Earth to facilitate the sharing and interaction of geospatial data are described and summarized in this paper first. Some of solutions are applied to two-dimensional mapped data to render the data into Google Earth via Earth science-specific software and keyhole markup language. A 3D model based innovative method is proposed here to visualize and display the three-dimensional atmospheric vertical profiles derived from A-Train constellation satellites in the form of 3D orbit curtain in Google Earth. This visualization capability extends awareness and visibility of NASA Earth science data to massive Google Earth user groups, including the general public. The availability of many scientific results in Google Earth enables easy and convenient synergistic research, advancing collaborative and globalized scientific research on a virtual platform.
The architecture of a virtual grid GIS server
Pengfei Wu, Yu Fang, Bin Chen, et al.
The grid computing technology provides the service oriented architecture for distributed applications. The virtual Grid GIS server is the distributed and interoperable enterprise application GIS architecture running in the grid environment, which integrates heterogeneous GIS platforms. All sorts of legacy GIS platforms join the grid as members of GIS virtual organization. Based on Microkernel we design the ESB and portal GIS service layer, which compose Microkernel GIS. Through web portals, portal GIS services and mediation of service bus, following the principle of SoC, we separate business logic from implementing logic. Microkernel GIS greatly reduces the coupling degree between applications and GIS platforms. The enterprise applications are independent of certain GIS platforms, and making the application developers to pay attention to the business logic. Via configuration and orchestration of a set of fine-grained services, the system creates GIS Business, which acts as a whole WebGIS request when activated. In this way, the system satisfies a business workflow directly and simply, with little or no new code.
Routing algorithm analysis of the distributed virtual geographic environment oriented P2P network
Xicheng Tan, Liang Yu, Fuling Bian
Distributed Virtual Geographic Environment(DVGE) faces some challenges and problems including the factor of the mass data of VGE, the band width of network, the numerous requests and economic factors, etc. These problems directly cause the current DVGE could not provide the public with high-quality service under current network mode. Hence, this paper brings forth a research on large-scale peer-to-peer network extension of DVGE as well as a deep study on network framework and the routing algorithm of it. Finally, we conduct a simulation of the DVGE based on the routing algorithm.
A spatial information crawler for OpenGIS WFS
Jun Jiang, Chong-jun Yang, Ying-chao Ren
The growth of the internet makes it non-trivial to search for the accuracy information efficiently. Topical crawler, which is aiming at a certain area, attracts more and more intention now because it can help people to find out what they need. Furthermore, with the OpenGIS WFS (Web Feature Service) Specification developed by OGC (Open GIS Consortium), much more geospatial data providers adopt this protocol to publish their data on the internet. In this case, a crawler which is aiming at the WFS servers can help people to find the geospatial data from WFS servers. In this paper, we propose a prototype system of a WFS crawler based on the OpenGIS WFS Specification. The crawler architecture, working principles, and detailed function of each component are introduced. This crawler is capable of discovering WFS servers dynamically, saving and updating the service contents of the servers. The data collect by the crawler can be supported to a geospatial data search engine as its data source.
The research on structure and development of the digital Earth prototype system
Lanwei Zhu, Huadong Guo, Changlin Wang
Digital Earth (DE) is a virtual presentation of the planet based on geographic coordinate, and is an information system with tremendous amount of multiple resolutions and multiple scales data as shown in multiple dimensions. Since the exact description about DE has not completed, most experts have their own understanding of DE, so there are a lot of various digital earth prototype system was developed, such as the Alexandria digital earth modeling system developed by the UCSB, digital earth prototype developed by the NASA, and earth simulator developed by the Japan and so on. Each of them has their own infrastructure and characteristics in developing process. Besides, there are still many commercial digital earth software popularly, such as the famous Google earth, word wind, skyline, and blue link and so on. They have the one biggest common that is all of them were based on the vast remote sensing image and represented by virtual reality technology. But when we reviewed the current situation of digital earth research presented from the outcomes of the International Symposium on Digital Earth four times, and investigated most of these digital earth system and software, we found the studies on digital earth system have some shortcomings. Therefore, facing this situation, in this paper, firstly, we will review the situation and the development of the Digital Earth research. Then, we will emphasize on how to construct the Digital Earth Prototype and develop its system from some new perspectives by the most prevalent techniques.
Design and implementation of a geospatial portal
Geospatial portals use Web Services to publish available geospatial data and processing services, help applications find them and invoke services or retrieve data. OGC has developed Geospatial Portal Reference Architecture to assist to implement a standards-based geospatially enabled portal application. The Geospatial Portal Reference Architecture is a major for E-Government, National Spatial Data Infrastructures, enterprises and Information Communities. It enables geoprocessing interoperability that makes it possible to exchange heterogeneous geographic information content and share a wide variety of geospatial services over the World Wide Web. In this article, we study the Geospatial Portal Reference Architecture. On the basis of this reference, we design and implement a geospatial portal. This article describes the architecture of this portal, development and deployment of this portal.
Real-time visualization of virtual geographic environment using the view-dependent simplification method
Jun Zhu, Hui Lin, Bingli Xu, et al.
A real-time virtual geographic environment (VGE) can serve as interactive, intuitive visualization tools for exploring, analyzing, synthesizing, and simulating multi dimension geo-data and complex geo-phenomena. The VGE scene can be constructed by terrain models, building models, and natural gaseous phenomena models. This paper used a viewdependent simplification method to improve the rendering efficiency of the VGE scene. The continuous level of detail technique(C-LOD) algorithm was adopted to achieve high frame rates by generating an approximate view-dependent triangulation of large terrain scene. Meanwhile image-based rendering techniques such as the imposter billboard were used to speed up the visualization of 3D object models (e.g., 3D building, 3D trees, smoke, cloud and so on). Using the Pearl River Delta (PRD) region in China as a case area, the visualization environment was built to support real-time rendering of larger-scale geo-scene. Experiment results prove that the scheme addressed in the paper can improve the overall efficiency.
Extending a geocoding database by Web information extraction
Yunchao Wu, Zheng Niu
Local Search has recently attracted much attention. And the popular architecture of Local Search is map-and-hyperlinks, which links geo-referenced Web content to a map interface. This architecture shows that a good Local Search not only depends on search engine techniques, but also on a perfect geocoding database. The process of building and updating a geocoding database is laborious and time consuming so that it is usually difficult to keep up with the change of the real world. However, the Web provides a rich resource of location related information, which would be a supplementary information source for geocoding. Therefore, this paper introduces how to extract geographic information from Web documents to extend a geocoding database. Our approach involves two major steps. First, geographic named entities are identified and extracted from Web content. Then, named entities are geocoded and put into storage. By this way, we can extend a geocoding database to provide better local Web search services.
Design and implementation of one WebGIS system based on Oracle and Ajax schema
Junwei Zhang, Zhongliang Cai, Weifan Li, et al.
WebGIS is the technology which publishes the geographic information service through the internet; it is changing more perfect after years with rich information, perfect user experience, which offer convenient geographic information services to people. This paper analyzes the technology and the schema used in the WebGIS today, and puts forward a schema which is based on oracle spatial, Ajax, JavaScript and so on. First, it uses oracle 10g to store the spatial data in the service, which provide GEOLOC field to store the spatial information and some spatial query and analysis functions and operators which make it easy and fast to realize spatial computation. Second it uses Ajax schema which realize asynchronous operations between client and service, and let the user do not need to wait before the service return the result. Third it uses the tile method that the large map is sliced up into many tiles and stored in the server. When the user visits the site, it just needs to download the several small tiles to visualize. Last, in the client, many operations such as pan, zoom and so on are realized based on the pure JavaScript. This schema solves the big data transmission through the internet, which reduce the response time when people visit the site and improve the users' experience.
An object-oriented spatial data model for virtual geographical environment
Yongjun Wang, Weitao Che, Rui Cao, et al.
This paper presents a spatial data model used for modeling geospatial data in virtual geographical environment. Most traditional spatial data modeling approach in geographical information system abstracts physical world with spatial entity and relationship between each other, put emphases on representing spatial feature and their topologies, whilst virtual reality system focus on capacity of keeping vivid rendering, i.e. high fidelity. Taking into account both topological characteristic of spatial data model in GIS and spaghetti characteristic of in VR, We introduce here an integrated spatial data model which could represent both topological and non-topological spatial data and underpin both various spatial analysis functions and real-time rending visualization effectively. This object-oriented method model topological feature separately from geometrical data and links them by a couple link, by which user can access different aspect of spatial data in specific application context. A virtual geographical scene management framework based on above spatial data model is introduced at the last.
VRLane: a desktop virtual safety management program for underground coal mine
Mei Li, Jingzhu Chen, Wei Xiong, et al.
VR technologies, which generate immersive, interactive, and three-dimensional (3D) environments, are seldom applied to coal mine safety work management. In this paper, a new method that combined the VR technologies with underground mine safety management system was explored. A desktop virtual safety management program for underground coal mine, called VRLane, was developed. The paper mainly concerned about the current research advance in VR, system design, key techniques and system application. Two important techniques were introduced in the paper. Firstly, an algorithm was designed and implemented, with which the 3D laneway models and equipment models can be built on the basis of the latest mine 2D drawings automatically, whereas common VR programs established 3D environment by using 3DS Max or the other 3D modeling software packages with which laneway models were built manually and laboriously. Secondly, VRLane realized system integration with underground industrial automation. VRLane not only described a realistic 3D laneway environment, but also described the status of the coal mining, with functions of displaying the run states and related parameters of equipment, per-alarming the abnormal mining events, and animating mine cars, mine workers, or long-wall shearers. The system, with advantages of cheap, dynamic, easy to maintenance, provided a useful tool for safety production management in coal mine.
The study of land spatial data celerity transmission on-line
Li-ting Zhang, Shi-jian Zhou, Ya-nan Fan
According to land spatial data sharing demands, study the relation for special data transmission velocity on-line and data quantity by experiments in this contribution. It has educed some valuable conclusions through analysed the result of experimentation of the on-line land spatial data piecemeal transmission experiment. When transmission's block data size of the land spatial data is in the 1MB scope, the each time transmission's speed time is the shortest when the block data size is 8KB.Certainly,the transmission's speed time is Not too discrepancy when each time the transmission's block data size is between 4KB and 32KB. When transmits the land spatial data size between 1MB and 200MB, the block data size which waste the least transmission time is 32KB. When transmits the land spatial data size around 350MB, the block data size which waste the least transmission time is 512KB.
Location-Based Services and Parcipatory GIS
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Based on 3G and RFID logistic delivery management system application and practice analysis
Xiaojun Li, Longjun Peng, Kaiwen Zhong, et al.
This article in view of the Logistic Delivery Management characteristic, analysis the logistic delivery management cannot satisfy requests rapid reaction and conformity transportation at present and so on. This article elaborated based on 3G (GIS, GPS, and GPRS) and RFID technology logistic delivery contents and so on management system, system design and architecture design, and its effective integration. The system design mentality uses the systems engineering method, follows the humanist idea, and embarks from user's demand, according to the user demand and the network request, divides according to the laminated structure into the decision-making strata, the service level, the management maintenance level and the technical support level 4 levels. The overall structural design including the system function structural design and the software system design, and take some province logistic delivery management system in management service as an example, introduced the design mentality and the application way.
Mining moving object trajectories in location-based services for spatio-temporal database update
Danhuai Guo, Weihong Cui
Advances in wireless transmission and mobile technology applied to LBS (Location-based Services) flood us with amounts of moving objects data. Vast amounts of gathered data from position sensors of mobile phones, PDAs, or vehicles hide interesting and valuable knowledge and describe the behavior of moving objects. The correlation between temporal moving patterns of moving objects and geo-feature spatio-temporal attribute was ignored, and the value of spatio-temporal trajectory data was not fully exploited too. Urban expanding or frequent town plan change bring about a large amount of outdated or imprecise data in spatial database of LBS, and they cannot be updated timely and efficiently by manual processing. In this paper we introduce a data mining approach to movement pattern extraction of moving objects, build a model to describe the relationship between movement patterns of LBS mobile objects and their environment, and put up with a spatio-temporal database update strategy in LBS database based on trajectories spatiotemporal mining. Experimental evaluation reveals excellent performance of the proposed model and strategy. Our original contribution include formulation of model of interaction between trajectory and its environment, design of spatio-temporal database update strategy based on moving objects data mining, and the experimental application of spatio-temporal database update by mining moving objects trajectories.
A geospatial collaboration information system for city environment assessment based on adaptive workflow
Shanzhen Yi, Yaodi Zhou, Lijun Li, et al.
City environment assessment based on cyber-infrastructure includes the activities of information exchange, information system collaboration and service integration among multiple departments. The method of adaptive service workflow (ASW) for geospatial collaborative system is proposed. With considering of the service quality and optimization algorithm, the virtual workflow (VW) and optimized selection of service (OSS) model are given for the selection of the best service in distributed computing environment. An application example of city environment assessment for poison gas diffusion is developed with the information collaboration between weather bureau, city construct department and environmental department, and the experiment result of diffusion plume is visualized and overlapped with base map on Web client.
Application of mobile GIS in special equipment inspection based on PDA
Zhirong Chen, Caijiang Xu
This paper discusses how to apply the mobile GIS technology to the common special equipment inspection business to meet the requirements of efficient management. The concepts of "special equipment" and "mobile GIS" are introduced at beginning. Then we analyze the business background and the present technique research; put forward a mobile GIS solution apply to special equipment inspection. A Special Equipment Inspection System is designed independently. The system architecture and database structure are discussed in detail. In the mobile environment, three key technologies are especially discussed in the paper, such as the interface design adapt to PDA device, data alternate mechanism and other embedded development attentions. The system has been used in Hangzhou Bureau of Quality and Technical Supervision for special equipment management, and gotten good result. So the requirements of scientifically manage the special equipment and establish e-government are completed met.
A reusability and efficiency oriented software design method for mobile land inspection
Wenwen Cai, Jun He, Qing Wang
Aiming at the requirement from the real-time land inspection domain, a land inspection handset system was presented in this paper. In order to increase the reusability of the system, a design pattern based framework was presented. Encapsulation for command like actions by applying COMMAND pattern was proposed for the problem of complex UI interactions. Integrating several GPS-log parsing engines into a general parsing framework was archived by introducing STRATEGY pattern. A network transmission module based network middleware was constructed. For mitigating the high coupling of complex network communication programs, FACTORY pattern was applied to facilitate the decoupling. Moreover, in order to efficiently manipulate huge GIS datasets, a VISITOR pattern and Quad-tree based multi-scale representation method was presented. It had been proved practically that these design patterns reduced the coupling between the subsystems, and improved the expansibility.
The research of spatial information communication and cognition theory in LBS system
Bo Gao, Fangjie Wan, Ling Xi, et al.
With the rapid development of LBS system in recent years, the existed communication and cognition model cannot describe its features entirely. After the analysis of the features of the LBS system, aiming at the limitations of existed communication and cognition theory, this paper proposes the spatial information communication model in LBS system and the cognition model of LBS subscribers.
Research on digital city geographic information common services platform
Dequan Chen, Qunyong Wu, Qinmin Wang
Traditional GIS (Geographic Information System) software development mode exposes many defects that will largely slow down the city informational progress. It is urgent need to build a common application infrastructure for informational project to speed up the development pace of digital city. The advent of service-oriented architecture (SOA) has motivated the adoption of GIS functionality portals that can be executed in distributed computing environment. According to the SOA principle, we bring forward and design a digital city geographic information common services platform which provides application development service interfaces for field users that can be further extended relevant business application. In the end, a public-oriented Web GIS is developed based on the platform for helping public users to query geographic information in their daily life. It indicates that our platform have the capacity that can be integrated by other applications conveniently.
Research on the efficiency of the spatial information service in the P2P network
Lian Duan, Baoqing Hu
Now most of the spatial information service applications still adopt the centralized pattern, which brings the network congestion or single point of failure to the side of center server. But the P2P technique takes away the bottleneck in data transmission exists in traditional C/S model by virtue of its multilink self-adaptive mechanism of the data transmission, which has a magnitude meaning for researches on the spatial information service delivering. As the spatial data has the characteristic of the massive volumes and client change the interesting spatial area so frequently that the spatial application efficiency is sharply decreased, the author brought forward a layered P2P architecture of the spatial data interoperation and flexible group mode in P2P network. A mechanism of the layered query queue of the oriented association and the self-adapted cache mode were introduced to adjust the peer loading and the link numbers for the reliable data capture. In this way, we can provide the each peer the rapid data transmission speed, the great data transmission reliability and the better user experience. A prototype was developed and it proved the efficiency of this P2P spatial information service framework. At last the futures of involved techniques and methods are concluded.
Building simplification algorithms based on user cognition in mobile environment
Jie Shen, Junfei Shi, Meizhen Wang, et al.
With the development of LBS, mobile map should adaptively satisfy the cognitive requirement of user. User cognition in mobile environment is much more objective oriented and also seem to be a heavier burden than the user in static environment. The holistic idea and methods of map generalization can not fully suitable for the mobile map. This paper took the building simplification in habitation generalization as example, analyzed the characteristic of user cognition in mobile environment and the basic rules of building simplification, collected and studied the state-of-the-art of algorithms of building simplification in the static and mobile environment, put forward the idea of hierarchical building simplification based on user cognition. This paper took Hunan road business district of Nanjing as test area and took the building data with shapfile format of ESRI as test data and realized the simplification algorithm. The method took user as center, calculated the distance between user and the building which will be simplified and took the distance as the basis for choosing different simplification algorithm for different spaces. This contribution aimed to hierarchically present the building in different level of detail by real-time simplification.
Research on custom-built generation of GIS application software based on metadata
Lu Hong, Fu Zhang, Zihui Zhang, et al.
In order to decrease the workload of code development, and to support the reuse of common functions and customization of personal functions, the paper proposes custom-built generation platform of GIS application software based on metadata. The platform divides the GIS application software into three parts: user interface, business logic and functional model. The three parts are loosely coupled based on metadata. The design of multi-layers loosely coupling indicates the system flexibility. It allows users to customize user interface, function and data to meet their personal demands. The platform locates resources rapidly based on metadata, and then customizes the GIS application software including basic GIS functions, personal user interface and flexible data. For validating the platform, the urban geologic survey information system is generated by the platform as a test. The result shows that the platform achieves the hot-plug of extensional components by modifying metadata and provides good reuse of GIS functions. Further more, it hides the diversity of GIS components. It simplifies the development of GIS application software and improves the efficiency of development.
Design and implementation of epidemiological field investigation method based on mobile collaboration
Lihui Zhang, Dongchuan Wang, Mingxiang Huang, et al.
With the development of mobile technologies and the integration with the spatial information technologies, it becomes possible to provide a potential to develop new techno-support solutions to Epidemiological Field Investigation especially for the disposal of emergent public health events. Based on mobile technologies and virtual geographic environment, the authors have designed a model for collaborative work in four communication patterns, namely, S2S (Static to Static), M2S (Mobile to Static), S2M (Static to Mobile), and M2M (Mobile to Mobile). Based on the model mentioned above, this paper stresses to explore mobile online mapping regarding mobile collaboration and conducts an experimental case study of HFRS (Hemorrhagic Fever with Renal Syndrome) fieldwork, and then develops a prototype system of emergent response disposition information system to test the effectiveness and usefulness of field survey based on mobile collaboration.
High precision mobile location framework and its service based on virtual reference station of GPS
Chun Liu, Liangyu Sun, Lianbi Yao
The wireless communication technology and space technology are synchronously developed in recent years, which bring up the development of location based service (LBS). At present, many location technology methods were developed. However, all these methods can only provide a relative poor location precision and depend on high cost. The technology of Virtual Reference Station (VRS) of GPS is then involved in this paper. One of the objective in this paper is aim to give the LBS position structure to improve the mobile location position when a mobile position instrument is connected with VRS network. The cheaper GPS built-in Personal Designer Aid (PDA) is then used to achieve a higher precision by using RTCM data from existing VRS network. In order to obtain a high precision position when using the low-cost GPS receiver as a rover, the infrusture of the mobile differential correction system is then put forward. According to network transportation of RTCM via internet protocol (NTRIP), the message is communicated through wireless network, such as GPRS, CDMA and so on. The rough coordinate information is sent to VRS control center continuously, and then the VRS correction information is replied to rover in the data format of RTCM3.1. So the position will be updated based on mathematic solution after the decoding of RTCM3.1 data. The thought of LBS position can improve the precision, and can speed the LBS.
Copyright protection for GIS vector data production
A. Li, W. Zhou, B. Lin, et al.
Limited by the characters of GIS vector data, such as variety and complexity of expression, universality, mass, disorder and pretty good privacy, etc., the traditional copyright protection methods for image and audio productions cannot be applied into GIS vector data productions directly. In this paper, a solution to copyright protection of GIS vector data productions is proposed. Firstly, information characteristics, data organization and storage characteristics and attack characteristics of GIS vector data are comprehensively analyzed. Secondly, based on hash, file filter driver, dynamic encryption and decryption, the key techniques including zero-watermarking generation, access control, and data content protection are described. Finally, a copyright protection frame of GIS vector data is put forward.
Research on visual modeling for geospatial services composition
Zhipeng Gui, Huayi Wu, Yumin Chen
Web services and web service composition technology have become the primary methods to realize geospatial information sharing and interoperability. There are various integration models and many specifications for web services composition, BPEL4WS is the most typical and prevailing one. But BPEL4WS is IT-oriented, the syntax structure is complicated, a well understanding to XML specifications and web services specifications is demanded, the way to describe processes and define activities in BPEL4WS are different from ways in certain domain, service contracts need early binding before the process instance execution. For above reasons, BPEL4WS is not suit for geospatial processing process's visual modeling. In this paper, an abstract geospatial service chain model based on data-dependent relationship is designed. A mapping algorithm is also proposed for translating the abstract service chain model into BPEL4WS form. So geospatial experts who are not web services experts can intuitively modeling service chain, translate the model into BPEL4WS style and execute it using BPEL4WS engine. Based on these researches, a geospatial web service chain visual modeling platform prototype is built, aiming to meet modeling demand of geospatial domain experts and common users.
The foundational theory and conceptual model of cooperative generalization of multi-elemental geographic information
Yi Long, Shilin Cui, Jie Shen
Geographic information generalization is a necessary means for scale transform of geometric and attributive information of the geographic spatial object sets under the GIS environment. This transformation relates to the complicated spatial and attributive relations within one geographic object, among different objects or elements rather than an isolated or single-elemental object. Thus, one of the ways to solve the conflicts among objects in the generalization is to adopt the strategy which is called he multi-elemental cooperative generalization (MECG), viz. to take the objects of different geographic elements into account. This paper mainly emphasizes the constrained relations (including spatial relation and structural relation) among different elements in generalization process. In this paper, a "from-above-to-below" concept model of multi-elemental cooperative generalization for some geographic elements is also discussed.
3D Modeling and Visualization
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Coal bed 3D modeling based on set theory and unparallel ATP
Qingwei Zhu
Although spatial objects of our world have an intrinsic three dimensional (3D) natures, 3D data modeling and 3D data management have so far been neglected in spatial database systems and Geographical Information Systems, which map geometric data mainly to two-dimensional abstractions. But increasingly the third dimension becomes more and more relevant for application domains. Large volumes of 3D data require a treatment in a database context for representing, querying, and manipulating them efficiently. After detailed researching on the mechanism of Modeling of the Geology Body, a new compositive data model is brought forward based on the joining of set theory (for short ST) and Unparallel Analogical Triangular Prisms (for short UATP). Spatial entity is decomposed into five fundamental kinds of data types in this model, including 3D point (3DP), 3D line (3DL), 3D sample surface (3DSS), 3D surface (3DS), and 3D volume (3DV). Meanwhile, nine data structures concerned are put forward, including node, TIN edge, side edge, arc edge, TIN surface, sample surface, quadrangle, UATP, and 3DSVC. Based on this, system of modeling and simulation for spatial entity are designed. Fault and mining roadway are presented as examples. This paper aims at investigating the complex inherent features of 3D data and presents an abstract, formal data model called ST (Set Theory). The data model comprises a set of three-dimensional spatial data types together with a collection of geometric set operations. The result shows that the data model based on set theory and UATP can improve speed and accuracy degree during process modeling. So, the main point in this paper is reconstruction of 3D Geological models, other question, such as: topological relations, data volumes as a key question for further study.
Construction and visualization of complicated objects for 3D GIS
Dewen Seng, Zhechen Song, Hongxia Wang
Three dimensional (3D) construction and visualization has become an integral part in many GIS and their applications. This paper examines how 3D visualization systems can be used with and integrated into GIS. We analyze several key characteristics visualization techniques should satisfy in order to be used efficiently by GIS, and show how GIS can provide visualization and animation features for geo objects by embedding the visualization system. The approach for the construction and visualization of complicated mining engineering environment implemented in the system is described in detail. Aspects like presentations of multidimensional data with spatial dependence, navigation in the geographical frame of reference and in time, interaction techniques are presented. Real data derived from an iron mine of China demonstrates the effectiveness and efficiency of the system.
Simplification and rectangularity of building polygon based on least squares adjustment theory in map generalization
Pengcheng Liu, Tinghua Ai, Jifang Deng
This paper presents a method of building feature generalization through boundary division and line approximation according to Least Squares Adjustment theory. How to detect a point set and divide the segments is investigated in detail in the paper. Based on the Least Squares Adjustment theory with constraint conditions, the paper offers a model of rectangularity of building-polygon on condition that the sum of the squares of displacement distances of all points is minimum. These solutions have been realized in a software GenTool, which is an interactive map generalization software in real applications.
A hierarchical visualization model of the global terrain based on QTM
Jian-jun Bai, Chao-de Yan, Xue-sheng Zhao
A global multi-resolution digital elevation model (DEM) and a feasible solution for its visualization and management remains a challenging vision. In this paper a multi-resolution DEM based on the ellipsoidal triangular meshes is made to approximate to the earth surface. It was built through quaternary triangular mesh (QTM) hierarchical tessellation of the ellipsoidal surface. In order to achieve fast access, we organize the global DEM data as a hierarchy of Diamonds and indexing them based on the linear quadtree. Furthermore, a LOD is built through recursive subdivision of each Diamond, and an approach of viewpoints-based data extraction based on the neighbor-Diamond searching from the global DEM data is implemented for visualization. All this is backed with an implementation of a prototype computer system.
Scalable 3D GIS environment managed by 3D-XML-based modeling
Beiqi Shi, Jianxun Rui, Neng Chen
Nowadays, the namely 3D GIS technologies become a key factor in establishing and maintaining large-scale 3D geoinformation services. However, with the rapidly increasing size and complexity of the 3D models being acquired, a pressing needed for suitable data management solutions has become apparent. This paper outlines that storage and exchange of geospatial data between databases and different front ends like 3D models, GIS or internet browsers require a standardized format which is capable to represent instances of 3D GIS models, to minimize loss of information during data transfer and to reduce interface development efforts. After a review of previous methods for spatial 3D data management, a universal lightweight XML-based format for quick and easy sharing of 3D GIS data is presented. 3D data management based on XML is a solution meeting the requirements as stated, which can provide an efficient means for opening a new standard way to create an arbitrary data structure and share it over the Internet. To manage reality-based 3D models, this paper uses 3DXML produced by Dassault Systemes. 3DXML uses opening XML schemas to communicate product geometry, structure and graphical display properties. It can be read, written and enriched by standard tools; and allows users to add extensions based on their own specific requirements. The paper concludes with the presentation of projects from application areas which will benefit from the functionality presented above.
Analysis of events in 3D building models
Hongchao Fan, Liqiu Meng
This paper addresses the nature of events in 3D building models. Events are characterized by their structures, tenses and temporal attributes. They can be also distinguished in different types in terms of changes in geometries, attributes and textures. There are up to 13 temporal topologic relationships between two arbitrary events of different lifespan. These relationships may change with varying temporal resolutions. On the basis of the inherent dependence that exists between the spatial and temporal resolutions, a mathematical model is established to describe the relative significance of an event that occurs to geometries or façade textures. Since 3D buildings are the most important object type that characterizes the dynamic nature of a city, the investigations on their events can serve as a conceptual basis for modeling, acquisition, visualization and retrieval of a 4D virtual city environment.
Conceptual modeling of spatial data generalization in GIS
Aiqin Li, Yi Deng, Mingfeng Li, et al.
Conceptual modeling is one of the most vital aspects of digital map generalization study, but at the same time it is probably the least understood. The relationship between spatial data generalization in GIS and map generalization is very close. However, distinctions exist at the same time. Based on analysis of massive references, the interrelationship of multi-scale, manual map generalization, digital map generalization, geographic database, cartographic database and conceptual modeling are discussed. This paper proposes and tests a simple conceptual modeling for spatial data generalization in GIS.
On semantics-based spatial data preprocessing: a case study in non-ortho RS images mosaic
Daojun Wang, Jianhua Gong, Ai-Nai Ma
A Three-Level Information Architecture containing Syntactic Information, Semantic Information and Pragmatic Information is put forward in Comprehensive Information Theory (CIT). From this point of view, spatial data analysis is in cooperation with semantic information and Spatial Data Preprocessing (SDP) is corresponding to syntactic information. However, in many practical applications, SDP based only on syntactic information can not get a good effect. Semantics-based preprocessing may be an effective scheme. RS images mosaic is a typical SDP where optimal mosaic line extraction is the crux. Lots of researches based on syntactic information are effective just for orthophoto maps. In this paper, an overall optimal mosaic line extraction scheme has been addressed for non-Ortho RS images. It is argued that there is no projection error in the projection datum fitted by Ground Control Points (GCPs), or regional main height surface which can be recognized in medium resolution RS images. Based on above reasons, the method suggests that GCPs collecting for precise geometrical correction should be on the main height surface, as well as the mosaic line extracting for RS images mosaic. Three sheets of CBERS CCD images of Taiyuan are taken as the experimental data. According to the afore-mentioned method, by collecting GCPs in wide riverbeds, all three sheets are rectified to an existing ETM+ mosaic image. And then, the central lines of wide riverbeds in the overlapping areas are extracted as the mosaic line. The experimental result indicates that this method can extract an overall optimal mosaic line and eliminate the visual texture seam-line effectively, even for non-Ortho RS images. It concludes that SDP based on semantic information can play a good role in spatial data applications.
Parametric design method for geospatial data visualization and interactive map modeling
Gang Liu, Chonglong Wu, Kunqi Liu, et al.
Traditional environment of spatial data visualization and map design was oriented to idiographic geometric shapes and users were over limited to some details. Its disadvantages mainly are: (1) visualization model is not flexible and fully user-oriented; (2) the whole process of visualization scheme cannot be supported; (3) system cannot support rapid modification and effectively reuse of former results. The theory and method of Parametric Design was proposed in this paper to get a new solution. System constraint model of geosciences maps was set up, and the constraints were classified into four main types which are geometric constraint, structure topological constraint, standard constraint and attribute constraint. Based on the synthetic analysis and comparison of various constraint solving algorithms, the geometric constraint solving method based on graphics theory was introduced. And the system structure of parametric design system with one platform and five layers, and relative system function model were put forward. Case studies of some typical graphics designs were discussed. The result indicates that parametric design method can play an important role in representation of user's idea, interactive design of map structure and building the flexible graphics generation environment.
Implementation of magnifier effect in multi-scale display of electronic map
Fenli Jia, Xiong You, Yingzhen Liu, et al.
"Magnifier" is a multi-scale display form of electronic map which can display more important areas with more details and less important areas with fewer details. In order to implement magnifier, different part of the screen must display data of different scale, so mathematical basis, data organizing, display management all have to be improved. This paper discusses the implementation of magnifier on the aspects mentioned above and does some experiments.
A data quantity optimization algorithm in terrain visualization
Yabin Li, Jianhua Gong
In order to ascertain appropriate data quantity in terrain visualization for some certain computers, the relationship model of FPS and data quantity has been put forward in this paper. Regarding the model, the time of a whole terrain visualization cycle is divided into two parts: data unrelated time and data related time. Based on the relationship model, a data optimization algorithm is developed, and the influences of timer error and data reading error are considered in terms of the algorithm. The algorithm is tested in a terrain visualization system developed with C++, FLTK and OpenGL. The results of experiment shows that the algorithm can evaluate and quantify computer's visualization performance, and calculate the precise triangle amount quickly, thus the rendering rate of terrain visualization system can be controlled accurately.
Effective visibility analysis method in virtual geographic environment
Yi Li, Qing Zhu, Jianhua Gong
Visibility analysis in virtual geographic environment has broad applications in many aspects in social life. But in practical use it is urged to improve the efficiency and accuracy, as well as to consider human vision restriction. The paper firstly introduces a high-efficient 3D data modeling method, which generates and organizes 3D data model using R-tree and LOD techniques. Then a new visibility algorithm which can realize real-time viewshed calculation considering the shelter of DEM and 3D building models and some restrictions of human eye to the viewshed generation. Finally an experiment is conducted to prove the visibility analysis calculation quickly and accurately which can meet the demand of digital city applications.
Quantification analysis of 3D urban form based on GIS: a case study of downtown Nanjing
Shanshan Ge, Guoan Tang, Xin Yang
An approach to describe 3D urban form is proposed in this study. Central part of Nanjing is taken as study site.Firstly, quantitative attributes are proposed from urban geometry and its function, and they are compactness, elevation range, volume expansibility, diversity, dominance. Then, all the attributes are derived and spatial distributions are analyzed to reveal relationship between attributes and some geographical features. The result shows that the above five attributes closely correlate with land use; especially compactness, diversity and dominance reflect the feature of building configuration. Finally, a multi-spectrum image is produced by the optimal combination of attributes to classify urban form. The result shows that different blocks of different land use can be distinguished. This research reveals the spatial distribution of urban form properties and their relationships between some geographical features. This quantification analysis of #d urban form is a new way to study urban form from three-dimensional aspect.
3D GIS spatial operation based on extended Euler operators
Hongbo Xu, Guonian Lu, Yehua Sheng, et al.
The implementation of 3 dimensions spatial operations, based on certain data structure, has a lack of universality and is not able to treat with non-manifold cases, at present. ISO/DIS 19107 standard just presents the definition of Boolean operators and set operators for topological relationship query, and OGC GeoXACML gives formal definitions for several set functions without implementation detail. Aiming at these problems, based mathematical foundation on cell complex theory, supported by non-manifold data structure and using relevant research in the field of non-manifold geometry modeling for reference, firstly, this paper according to non-manifold Euler-Poincaré formula constructs 6 extended Euler operators and inverse operators to carry out creating, updating and deleting 3D spatial elements, as well as several pairs of supplementary Euler operators to convenient for implementing advanced functions. Secondly, we change topological element operation sequence of Boolean operation and set operation as well as set functions defined in GeoXACML into combination of extended Euler operators, which separates the upper functions and lower data structure. Lastly, we develop underground 3D GIS prototype system, in which practicability and credibility of extended Euler operators faced to 3D GIS presented by this paper are validated.
Management and services for large-scale virtual 3D urban model data based on network
Zhengwei He, Jing Chen, Huayi Wu
The buildings in modern city are complex and diverse, and the quantity is huge. These bring very big challenge for constructing 3D GIS under network circumstance and eventually realizing the Digital Earth. After analyzed the characteristic of network service about massive 3D urban building model data, this paper focuses on the organization and management of spatial data and the network services strategy, proposes a progressive network transmission schema based on the spatial resolution and the component elements of 3D building model data. Next, this paper put forward multistage-link three-dimensional spatial data organization model and encoding method of spatial index based on fully level quadtree structure. Then, a virtual earth platform, called GeoGlobe, was developed using above theory. Experimental results show that above 3D spatial data management model and service theory can availably provide network services for large-scale 3D urban model data. The application results and user experience good .
Study on the developing method of rendering and broadcasting large scale terrain
Yang Li, Yanyou Qiao, Dipei Wu, et al.
Rendering and broadcasting the large scale terrain on internet is a hot and challenging topic in the Computer Graphics research field. In order to get the ideal terrain rendering, some experts have put forward a couple of good solutions for Level of Detail (LOD) which effectively reduces the quantity of the presented triangles, including the quad-tree algorithm on which this paper is based. Rather than the quad-tree algorithm itself which has been discussed a lot, this paper has elaborated a series of methods used in developing this algorithm during the process of rendering and broadcasting large scale terrain. In this paper, we have discussed these methods in the following sequence: first terrain data preprocessing, then rendering and last broadcasting, in which order the practice will also follow. It has been proved that these methods are quite effective according to the success of the "Remote Forest Monitoring System," which is based on them.
Research on construction of large-scale 3D city models based on skyline prototype system
Jinjie Zhang, Tiyan Shen
The construction of large-scale three-dimension city models faces the problem that the data is too huge, the mission is too heavy, and the development cycle is too long. Facing so many types of buildings and other city objects, it is very difficult to finish the Construction of 3D city models quickly and efficiently using only one technical method. How to operate the construction of large-scale 3D city model based on multi-source data quickly and efficiently is a hot issue in current researches. This paper proposes the method of constructing large-scale urban three-dimension landscape and creating virtual reality by using Skyline, a powerful software of 3DGIS, which is based on two source data, RS image and DWG. It also gives a detailed illustration on the key problems related to the construction during the course of construction, such as modeling of the particular object, texture projection, etc.
Visualization analysis based on cell complex for 3D GIS
Liangchen Zhou, Guonian Lu, Yehua Sheng, et al.
As the theory and application requirement of 3d GIS are developing dramatically, 3D geological simulation is not only limited in the capability of visualizing spatial objects, and it has a deeper demand on three dimensions spatial analysis for geographic objects or phenomenon. Therefore, a lot of visualized analysis functions for practical projects are proposed by researchers. However, these researches usually come up with corresponding algorithms based on certain data model or data structure which is without a powerful portability. And the algorithms are often limited to specific requirement which has little expansibility. To solve this problem, a new 3D GIS data model for 3D geological simulation is advanced based on cell complex theory and correlative research results in the field of non-manifold geometric modeling. And a series of 3D set operators are defined to carry out virtual drilling, virtual cutting, virtual digging and virtual tunnel excavation analysis and so on. Compared with existing implementations, the new presented 3D GIS data model unifies the expression of wire frame, facial and volumetric model, which ensures the portability of algorithm. Set operators based on non-manifold geometric modeling possessing mathematical completeness have the ability to implement arbitrary geometric object operation, which can insure the expansibility of the algorithm.
A study on 3D modeling of building based upon photogrammetry
Lei Wu, Miaozhong Xu, Ming Li, et al.
This article has analyzed three-dimensional city building modeling demand based on photogrammetry and the photogrammetric method in the building's three-dimensional reconstruction and the three-dimensional urban building data updating aspect superiority. It has also discussed three-dimensional urban building modeling method, the workflow and the technology based on the photogrammetry, and finally achieved high accuracy in three-dimensional reconstruction of both wide range city buildings and a single complex building.
3D modeling of terrace in the Loess Plateau
Weixing Wang, Jinjin Zhang, Jianhua Gong
With the development of 3DGIS and virtual geographic environments, it is important and necessary to represent terrain in a more vivid form but keep geographic information precise too. At present, there is less study on the 3D representation of micro-landform in comparison with large scale 3D modeling of terrain. Regarding the building of a simulation environment that reflects the real situation of the Loess Plateau, it's necessary to consider the features of microlandform. This paper aims to explore the way of building 3D model of terrace in the Loess Plateau, which is a typical landscape in the region. According to the characteristics of terrace, level terrace, the most common type, is considered as a modeling object and a new method of feature based TIN (Triangular Irregular Network) modeling is put forward. Two key techniques regarding the method are terraces' feature extracting and the obtaining of object's elevation of points in each feature line to make TIN interpolation.
Interactive visualization of three-dimensional pipelines using Ajax and X3D
Zhe Zeng, Jianhua Huang, Yunjun Lu
The developments of three dimensional pipelines are mainly on the COM component of GIS software, three dimensional visualization library and client-sever software architectures. These methods are still not sufficient in supporting remote management of 3D pipelines, because the client and the server involved in the process may require two-way communication frequently as well as modeling results visualization intuitively. In this paper we proposed a solution to 3D pipeline management system, which provides convenience of operation, exactness of position and rapidness of update for the pipelines in the web context. We realized web-based interactive visualization for 3D pipelines using AJAX and X3D.
3D groundwater flow modeling based on GIS
Fei Guo, Yehua Sheng, Liangchen Zhou, et al.
The geographical information system (GIS) has provided the effective tools to capture, store, manage, analyze and express the spatial information. Gradually, the research region has included the dynamical mechanism and the spatialtime characteristics of the geography process, transmission mechanisms, uncertainty (multi-solutions), predictability, and so on. Corresponding, GIS modeling is one of hotspots of current GIS research. The paper is the embodiment of GIS modeling methods applied to geo-simulation research. Also it provides the model support for the management of the ground water resources. In this paper, the methods for constructing the ground-water conceptual model through 3D stratum model are discussed. Firstly, the constructing method of delaunay triangulation with constraint conditions is proposed, which is suitable to the ground-water flow simulation. Then stratum (or aquifer) multi-DEMs are completed. Based on the multi-DEMs, the Su-Xi-Chan hydrogeological conceptual model is reconstructed by irregular Tri-prism. In order to prevent dispersed irregular tri-prism voxels from disunity, the spatial index mechanism is established for groundwater model. Finally, the 3D groundwater simulation model is integrated with GIS, which can provide data for 3D numerical simulation. The results indicate that the integration of 3D GIS and geo-analysis model be convenient and can accelerate process simulation of geo-science.
Research and development of visualization-analysis-oriented digital map data model
Qingwen Qi, Yuajuan Liang
What we are now facing is the dilemma when we try to integrate Digital Cartographic Model (DCM), which is symboloriented model, and Digital Landscape Model (DLM), which is the geographical entity and topology oriented model. Basic theory of map modeling method of geographical data is researched. A new type of digital map data model is raised out and designed, including four levels as conceptual, logical, and physical model to satisfy visualization and spatial analysis at the same time. The formation of the digital map logic model relies on abstracting and summarizing the world by means of the object-oriented method, putting forward the conceptual model of the object-oriented digital map according to the OGC abstract norm, dwelling on all the kinds of objects in the model and logical design in which spatial data, attribute data, symbols, and topology are all stored in relational database, in form of various but inter-linked relational tabulations as point, line, area, label, symbol, etc. And meanwhile, the author develops the data-modeling tool which turns the storage of the digital map in the relational database management system into realities, thus realizes digital map storage and manages in Microsoft SQL Server.
The research of selection model based on LOD in multi-scale display of electronic map
Jinming Zhang, Xiong You, Yingzhen Liu
This paper proposes a selection model based on LOD to aid the display of electronic map. The ratio of display scale to map scale is regarded as a LOD operator. The categorization rule, classification rule, elementary rule and spatial geometry character rule of LOD operator setting are also concluded.