Proceedings Volume 6418

Geoinformatics 2006: GNSS and Integrated Geospatial Applications

Deren Li, Linyuan Xia
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Proceedings Volume 6418

Geoinformatics 2006: GNSS and Integrated Geospatial Applications

Deren Li, Linyuan Xia
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Volume Details

Date Published: 28 October 2006
Contents: 4 Sessions, 65 Papers, 0 Presentations
Conference: Geoinformatics 2006: GNSS and Integrated Geospatial Applications 2006
Volume Number: 6418

Table of Contents

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Table of Contents

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  • Integration Methodology
  • GNSS
  • Mobile GIS Technology
  • Resources Management
Integration Methodology
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GIS/RS-based evaluation of regional ecological security: a case study of Wanquan County of Hebei Province around Beijing
Yunhai Zhu, Baiping Zhang, Xu Yu, et al.
The aim of this study was to develop a GIS/RS based evaluation system for regional ecological security (RES). Wanquan County of Hebei Province was taken as a case study area and 3 types of evaluating indicators, including vegetation changes, LUCC (land use/cover change) and soil erosion, processed by GIS/RS technologies, were selected. By the comprehensive index method, a quantitative evaluation model was built with the three types of indices based on GIS/RS technologies, and their weights were balanced by introducing least squares solution. The final evaluation image and the statistical results were generated in ArcGIS9.0/Spatial Analyst module, so the GIS/RS based model for RES was realized successfully. Through our case study, it was proved that the evaluation study on RES was improved by the intercross between Geoinformatics and Ecology. GIS was a powerful analysis tool, RS was an ideal data-source and GPS could provide the exact real-time positioning information for our study. Just because of the comprehensive application of "3S" technologies, the study on the evaluation of RES was lifted to the positioning, quantitative and visualized level.
The method for satellite orbit determination and its precision analysis based on bi-satellite positioning system
Jiongqi Wang, Haiyin Zhou, Deyong Zhao, et al.
Space-ground combined system is one of the current tendencies in the spacecraft measurement and control. The accomplishing of the Bi-satellite positioning system (BPS) can provide a possibility to realize our independent satellite space-ground measurement and control technology; also due to its advantages, such as all weather, all-time and relative high precision for orbit determination, so it can become a promising and efficient measurement and control means for LEO or MEO orbit determination. In this paper, founding on the actuality of this system and combining the demand for precise orbit determination of LEO and MEO, we advance the method of satellite orbit determination based on BPS, summarize its fundamental and composition, and present its observation model and flow for observation data, also research its mathematics model and method. This paper mainly researches and analyzes the system error characters and their parameter estimation in the process of orbit determination used by BPS. Finally, by simulation calculation and precision analysis, we research the correlation between the user satellite orbit determination precision and bi-satellite ephemeris error, data measurement precision and length of observation time, moreover, compare the ultimate precision influence caused by whether to estimate and deduct system error or not. All these work can afford theoretic basis for next project realization.
Sharing and interoperation of Digital Dongying geospatial data
Jun Zhao, Gaohuan Liu, Li-tao Han, et al.
Digital Dongying project was put forward by Dongying city, Shandong province, and authenticated by Ministry of Information Industry, Ministry of Science and Technology and Ministry of Construction P.R.CHINA in 2002. After five years of building, informationization level of Dongying has reached to the advanced degree. In order to forward the step of digital Dongying building, and to realize geospatial data sharing, geographic information sharing standards are drawn up and applied into realization. Secondly, Digital Dongying Geographic Information Sharing Platform has been constructed and developed, which is a highly integrated platform of WEBGIS. 3S (GIS, GPS, RS), Object oriented RDBMS, Internet, DCOM, etc. It provides an indispensable platform for sharing and interoperation of Digital Dongying Geospatial Data. According to the standards, and based on the platform, sharing and interoperation of "Digital Dongying" geospatial data have come into practice and the good results have been obtained. However, a perfect leadership group is necessary for data sharing and interoperation.
Detection of trees using airborne lidar data based on ArcGIS
Feifei Tang, Jingnan Liu, Xiaohong Zhang
In this article, we use the height difference between the first pulse and last pulse recorded by the airborne laser scanning system to implement a strategy for detection of trees, especially for relatively tall trees. The airborne lidar data we use include 3D coordinates and intensity information of first pulse and last pulse respectively, and the image file of the test area are also available. ArcGIS version 9.0, has been used as the implementation platform as which as effective data processing function and outstanding performance of data analysis such as TIN interpolation and 3D display. To extract trees from the raw data, the data is loaded into ArcGIS to create shapefile recognized by ArcGIS at first, and the corresponding attributes, coordinates, intensity and height difference computed by programming are stored. Then we select the data accord with the filtering condition, a threshold for height difference is given. All the comparisons of 3D coordinates and intensity occur between point data in the same row, in other words, between the first pulse and last pulse. We accept the first pulse which satisfies the height difference threshold as vegetation points. At last, a considerable result of detection of trees has been achieved.
Accuracy determination and visualization for image geo-correction
Beiqi Shi, Neng Chen, Chun Liu
There is two main factor of High-Resolution Satellite Imagery(HRSI) geometry correction. Besides mathematical models, Ground Control Points (GCPs) has played a big role on rectification. As how to determine the effect of GCPs in image geo-correction, the accuracy estimation of the control points is the main form by means of statistics. Yet this existing method shows nothing more than the partial expression in the statistic level. With the development of visualization technology, using the technology of spatial visualization for the accuracy determination affected by the GCPs and the whole expression are discussed in this paper. Taken affine rectification model and conformal rectification model as example, the paper has mainly deduced the relationship between the accuracy of arbitrary point and the control points. The Inverse Distance relationship is the result, therefore interpolation method related to the result is used to interpolate spatial accuracy for the image geo-correction. Based on above, the visualizations of accuracy is put forward to give the detail description for the quality of image geo-correction and the effect of GCPs' precision, quantity and distribution. The case of HRSI is adopted to give the explanation for the spatial visualization of accuracy of GCPs, and also some helpful conclusions are obtained for its availability. From the case, it can be obtained that the precision of control points after conversion in affine model is lower than that in conformal model according to the different scale parameters in x or y direction.
Prototyping an in-field collaborative environment for landscape decision support by linking GIS with a game engine
Tao Chen, Christian Stock, Ian D. Bishop, et al.
With public environmental awareness increasing, there are growing prospects for access to real-time data anytime and everywhere for decision support involving multiple users not only office-based but also remotely. This paper describes the development of a prototype system implementing an in-field collaborative visualisation environment in order to facilitate decision support in landscape planning and environmental management. Our initial development is based on live linking GIS with a fully immersive collaborative virtual decision environment which uses the commercial low-cost Torque Game Engine (TGE, www.garagegames.com). Game engines provide efficient image rendering, a built-in editor for interactive processing of terrain surface features and, in particular, sophisticated and robust client/server networked functionality for multi-user access. Anticipated research activities include the development of an interfacing Augmented Reality (AR) extension to the system, terrain feature library establishment and the deployment of a pilot project including in field mobile observation.
The accuracy influence of integrated GPS/INS for direct georeferencing in digital line scanning imagery
Yun Zhan, Chun Liu
With available high performance GPS/inertial systems (GPS/INS) witch supports direct platform orientation (DPO), direct georeferencing is shown to be a serious alternative to standard indirect image orientation using classical or GPS-supported aerial triangulation (AT). Since the positioning accuracy of direct georeferencing without ground control relies on the accuracy of the six exterior orientation parameters (EOP: three coordinates of the perspective centre, and three rotation angles known as φ, ω, κ ), special focus has to be laid on the analysis of the GPS/INS influence on the positioning accuracy. The investigations presented in this paper give an approach based on simulated data deriving from SPOT data. This paper describes the mathematical formulation of the model and analyses the results achieved by testing it on SPOT images observations for the external orientation. The ground coordinates of 40 ground control points (GCPs) are available and used as reference data for the results' analysis. In this paper, the investigation conclusions will be practical to GPS/inertial system application and manufacture, and be helpful to get knowledge of its affluence on positioning accuracy.
A new data integration approach for AutoCAD and GIS
Hongmei Ye, Yuhong Li, Cheng Wang, et al.
GIS has its advantages both on spatial data analysis and management, particularly on the geometric and attributive information management, which has also attracted lots attentions among researchers around world. AutoCAD plays more and more important roles as one of the main data sources of GIS. Various work and achievements can be found in the related literature. However, the conventional data integration from AutoCAD to GIS is time-consuming, which also can cause the information loss both in the geometric aspects and the attributive aspects for a large system. It is necessary and urgent to sort out new approach and algorithm for the efficient high-quality data integration. In this paper, a novel data integration approach from AutoCAD to GIS will be introduced based on the spatial data mining technique through the data structure analysis both in the AutoCAD and GIS. A practicable algorithm for the data conversion from CAD to GIS will be given as well. By a designed evaluation scheme, the accuracy of the conversion both in the geometric and the attributive information will be demonstrated. Finally, the validity and feasibility of the new approach will be shown by an experimental analysis.
Geometric correction and spatial visualization of accuracy on QuickBird imagery
Gang Qiao, Weian Wang
Since the successful launch of DigitalGlobe's QuickBird satellite on Oct 18th, 2001, QuickBird imagery has become the best choice for large-scaled mapping using high resolution satellite images. This paper first presents a quantitative evaluation of the geometric accuracy that can be achieved with QuickBird imagery using the metadata provided with DigitalGlobe's image products, then the technology of spatial visualization for the accuracy determination and the whole expression are put forward.
An object-based storage model for distributed remote sensing images
Zhanwu Yu, Zhongmin Li, Sheng Zheng
It is very difficult to design an integrated storage solution for distributed remote sensing images to offer high performance network storage services and secure data sharing across platforms using current network storage models such as direct attached storage, network attached storage and storage area network. Object-based storage, as new generation network storage technology emerged recently, separates the data path, the control path and the management path, which solves the bottleneck problem of metadata existed in traditional storage models, and has the characteristics of parallel data access, data sharing across platforms, intelligence of storage devices and security of data access. We use the object-based storage in the storage management of remote sensing images to construct an object-based storage model for distributed remote sensing images. In the storage model, remote sensing images are organized as remote sensing objects stored in the object-based storage devices. According to the storage model, we present the architecture of a distributed remote sensing images application system based on object-based storage, and give some test results about the write performance comparison of traditional network storage model and object-based storage model.
An integrated environment for spatio-temporal analysis, simulation, and representation for public health research
Haitang Hu, Shuming Bao, Bing Xu, et al.
Geographic space, as the arena within which all of the natural and social processes occur, and time, have become key research components of social science for the past two decades. However, most GIS software packages lack the predictive and analytic capabilities for complex problems, such as spatial statistical methods and spatial modeling. Meanwhile, the spatio-temporally explicit representation of complex, heterogeneous and dynamic geographic data sets is a particularly challenging issue. Many efforts have been made in developing tools for effective representation of health data, spatio-temporal analysis of the data, and the dynamic process simulation of disease transmission. To meet this demand, we attempted to develop a tool for integrating spatio-temporal analysis, simulation and representation of health data and processes. In this paper, we will introduce some methods for spatial temporal data analysis and their applications in public health. We'll describe the conceptual model of spatial temporal process simulation and the process-oriented spatio-temporal data model adopted in the tool we developed. After that, we'll present the framework of our integrated research toolkit, and demonstrate how to conduct analysis, modeling, and simulation with this software. Finally, we will discuss some issues for future studies.
Utility of neural net classification for remote sensing data based on an improved image fusion algorithm
Bofeng Cai, Rong Yu, Zengxiang Zhang
There are many different advantages and disadvantages in traditional subpixel classification methods such as uncertain classification accuracy, etc. which bring limitations for commonly application. In recent years, many algorithms have been used to resolve these problems. In this paper, based on an optimized image fusion algorithm, a comparison experiment on traditional maximum likelihood classification and neural net classification is performed. According to the classification accuracy data, the overall accuracy of classification increased from 81.67% to 89.67%.
Application of photogrammetry computer vision in intelligence visual surveillance
A new method for 3D rigid motion estimation from binocular sequence image of computer system in intelligence vision supervises is proposed in this paper. The appealing feature of this method is that it combines stereo vision and movement vision in computer vision literature, using the ideas in digital photogrammetry theory, fulfilling movement object location, measure and tracking by the object side image analyze method. It includes camera calibration; stereo-movement double matching restrict; calculation of objects movement parameters; pan-tilt unit movement control etc contents. The experimental result that pan-tilt unit movement control, which obtains object moves with uniform velocity and uniform acceleration in the straight line from the real binocular sequence images by the mentioned method, are presented.
Geometry simulation of HJ-1A satellite multi-spectral image
Remote Sensing Image Simulation, which provides the image according to the characteristics of sensor in geometry, spectral and radiometry, is a very significant issue before the satellite's launching. This paper is mainly detailed in the geometric characteristics of multi-spectral sensors and the process of image geometric simulation of 1A microsatellite in Environment and Disaster Monitoring Microsatellite Constellation (HJ-1A). The relationship among the swath, the convergent angle, and the Ground Sampling Distance (GSD) is studied. The ideal photography model based on the photogrammetric theory is set up according to part of orbit parameters and reasonable assumptions. The relationship between the image coordinates and the geodetic coordinates and the simulating image algorithm is put forward. Finally, some conclusions are drawn up from the results of the study.
A new method integration of 3S for mobile landscaping survey and update
Gen Tian, Xiao-hua Tong, Miao-long Liu
A new method integration of "3S" (geographic information system (GIS), global positioning system (GPS), remote sensing(RS)) for mobile landscaping survey and update is studied in mobile GIS. Several Key technologies are presented in the method, including spatial data model on mobile personal digital assistant (PDA), GPS data difference processing and representation in GIS, GPS coordinate transformation model in mobile GIS, the method of PDA integration of Total Station, the RS image process based on Mobile Device. A new object-oriented spatial data model based on mobile GIS is proposed that has high query and display efficient. A new least squares-based GPS transformation model is further proposed that has fast calculation speed, high adjustment accuracy and thus suitable for mobile GIS. An integrative Application system integration of "3S" for landscaping survey, update and management is therefore developed, including spatial data survey and update mobile GIS, spatial data processing and maintain desktop GIS and spatial data publication WEBGIS. A field test is carried out through this system in Shanghai, and the results show that the proposed model and methods are feasible for mobile landscaping information survey, update and gridding management.
Research on the theory and methodology of integrating GIS and MAS and its application in simulating pedestrians flows in a crowd's activity centre of Shanghai metropolitan
Miaolong Liu, Peng Chen
Based on the development trend of research on urban morphology and its evolution from macro scale to micro scale, a new tight-coupling integrating method of GIS and MAS has been discussed briefly in this paper. After analyzing the characteristics and mechanism of pedestrian's flows in a crowds' activity center in a metropolitan, a prototype and mathematical expression of pedestrian's flows simulation have been put forward in the paper. A few key expressions and techniques for treating the specific behaviors of pedestrians flows, especially how the individuals of the flows make a decision to follow a original designed direction, how to make a decision whether stop or change his movement and select a new direction when the individuals meet a obstacle have been explored and discussed in detail. Using some tools provided by general GIS systems (such as ArcGIS 9) and a few specific programming languages, a new software system integrating GIS and MAS applicable for simulating pedestrians flows in a crowd activity centre has been developed successfully. Under the environment supported by the software system, as an applicable case, a dynamic evolution process of the pedestrian's flows (dispersed process for the spectators) in a crowds' activity center - The Shanghai Stadium has been simulated successfully. The successful simulating of a case of emergence when one or more exits emerge accidents will be very useful for managing and treating crowds' safety in a lot of assembling centers. At the end of the paper, some new research problems have been pointed out for the future.
Research on the progress and direction of surveying and mapping
Qianjun Miao, Deren Li, Zhenfeng Shao
Based on the significance and strategic prospect of geo-informatization system, this paper researches the orientation of geo-informatization system in detail. It also discusses the architecture of geo-informatization system according to its development trend. At last, the five phases of geo-informatization system are compared and analyzed comprehensively.
GNSS
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Precise orbit determination of low Earth orbiters using undifferenced GPS data
Cui-lin Kuang, Fen Hou
Although POD with GPS has been tested using data from various satellites (e.g. CHAMP, GRACE etc.) with different approaches, there are still many open issues concerning the optimum way to determine LEO satellite orbits with GPS. The emphasis of this paper is to develop an efficient method for precise orbit determination of LEOs. To avoid the need for reference measurements from ground-based reference receivers, the analysis is based on an undifferenced processing of GPS code and carrier-phase measurements. The idea was to combine the kinematic and dynamic approaches, by using them interactively, in separate solutions, fitting dynamic orbits to kinematic orbit. So a purely kinematic orbit for the LEOs is obtained simultaneously with the reduced-dynamic orbit. Testing results show the precise of PPP kinematic orbit is about 22cm, and the precise of reduced-dynamic orbit is about 9cm. Also the reduced-dynamic orbit is smoother than PPP kinematic orbit.
Learning significant locations from GPS data with time window
Jian Tang, Lingkui Meng
The most important and common service of LBS is to provide the user of his location. In this paper we propose a method to cluster a period of GPS data into meaningful locations by using DBSCAN algorithm. With a time window constraint this method can even distinguish the locations of the same place where the user went at different time. The learned significant locations are important basis of further service, such as predicting the user's future movement, building the user's own map etc. At last, we introduce a prototype system based on the learning method to provide the place information where the user went before and the information is expressed in time-ordered and semantic landmarks directly.
The simulation of GTRF initial realization using GPS data
Rong Zou, Chuang Shi, Zhimin Liu
The GTRF initial realization and long-term maintenance follows the state of the art of TRF implementation. In this paper, the background of GTRF realization and the history of ITRF establishment were reviewed firstly. The precious experience gained from IERS activities is very helpful in GTRF realization, based on such situation, so the combined model and strategy for simulating GTRF initial realization by GPS data in the first stage of Galileo project were discussed and. And then 200 GPS Weeks data in SINEX format from three IGS analysis centers COD, ESA and GFZ was used as input data, we apply loose constraint, use the variance factor of weekly time series as apriori weight in the combination, and estimate station coordinate and 7 transformation parameters together. According to this simulation, the translation and scale parameters of three analysis centers are attained by weekly combined solution, while the rotation parameters are just estimated by the data from ESA. With these 7 transformation parameters, the GTRF can be initially realized by alignment to the ITRF by the GSS co-located with ITRF core stations.
Error compensation and high-precision baseline estimation in InSAR geolocation using GCPs
Jiying Liu, Jubo Zhu, Zenghui Hu, et al.
An exact and closed-form algorithm for InSAR geolocation is studied, then on the basis, an analysis of error propagation between measurements and geolocation solution was given. At the same time, from a new point of view, we propose a new method focused on the compensation of the difference of the slant ranges of two satellites. Eventually, appalling a method of baseline estimation which based on GCPs, we can obtain high precision baseline estimation from geolocation solutions after error compensation.
An improved TERCOM algorithm and its application in a submarine terrain aided navigation system
Zunyi Xu, Lei Yan, Guangjun Liu, et al.
Terrain contour matching (TERCOM) algorithm is the main one in the conventional terrain aided navigation system. When it has been directly applied to the submarine terrain aided navigation (STAN) system, the accuracy and stability are primely reduced. To solve these problems, the detail analyses about the particularities of the STAN and the disadvantages of the conventional TERCOM algorithm have been made. The improvement for the TERCOM algorithm on the measurement function, the water depth survey error and the scheme to prevent fail positioning has been done. Moreover, experiments with pedestrian simulation confirm the effectiveness of the improved TERCOM algorithm. The system achieves higher positioning precision than that of conventional one.
Fast ICA for deformation data processing
Yufeng Shi, Jinsheng Ning, Fengxiang Jin
The theory and method of deformation monitoring and deformation data analysis and processing are the research hot issues in surveying fields. Independent component analysis (ICA) is a novel explored data analysis method developed recently, which is used to find out representations of the Non-Gaussian multivariate data. Based on ICA and Fast ICA arithmetic, this paper proposed a novel method to process the deformation monitoring data and gets the deformation sub-patterns.
Simulation of satellite-to-satellite tracking data of interferometric SAR based on GPS
Xianqin Tu, Jing Yao, Defeng Gu, et al.
While space-borne synthetic aperture radar (SAR) has evolved into a mature technology over the past two decades, there is a growing interest in interferometric SAR applications. Precise relative state estimation is a necessary technique for the operation of multiple space vehicle on-orbit formation flying together, which is vitally important for the InSAR system. Carrier-phase Differential GPS (CDGPS) positioning has been proven to be an accurate technique for relative positioning and attitude determining between multiple vehicles. In order to analyze and assess the achievable accuracy based on satellite-to-satellite tracking (SST) by the US global positioning system (GPS), a modeling with corresponding simulation software is established to analyze relative state estimation of InSAR using CDGPS, which is a part of the InSAR Simulation System (ISSS). The models including SAR satellites model, GPS satellites model and observation error models are studied in this paper. The simulated observation data is obtained by employing these elaborately selected models, which can be used in the process of investigating orbit determination scheme, evaluating relative state estimation methods such as ambiguity resolution method, Kalman filtering technique and so on. The values of simulated model parameters can be customized to simulate satellites at different altitudes and tracking data with different errors.
Code and carrier phase multipath effects with GNSS receiver
Xiaoli Liu, Jingnan Liu, Zhigang Hong
It is well known that code and carrier-phase multipath, which has been under study for over two decades, is the limiting error sources in high-precision differential GPS applications. In virtually every study, however, the effects of autocorrelation function are considered little. This article focuses on the bounds of code and carrier-phase multipath error in terms of GNSS (Global Navigation Satellite Systems) signals autocorrelation functions, which result from a fundamental theoretical description and mathematical modeling of GNSS receiver. Firstly, an overview of the characteristics of the BOC (Binary Offset Carrier) signal ACF (autocorrelation function) is given in the paper. The impact on the DLL (delay-lock loop) and PLL (phase lock loop) discriminator functions are derived in the followed section and consequently a general description of multipath errors are obtained for the BOC signals. This quantifies the influence of limited bandwidth on receiver tracking error due to multipath. Finally, the simulation results show a distinct change in the error envelope for BOC signals from which has been got using current GPS C/A code signal.
Ice velocities on the front of Amery Ice Shelf, East Antarctica, from static GPS observations
Shengkai Zhang, Dongchen E, Zemin Wang
The Lambert Glacier-Amery Ice Shelf (LAS) system is the largest glacier-ice-shelf system in East Antarctica, the Amery Ice Shelf (AIS) and its tributaries drain ice from the LAS system. During the austral summer season of 2002/03, the 19th Chinese National Antarctica Research Expedition (CHINARE) carried out the first expedition on the Amery Ice Shelf and set up 7 GPS sites, During the austral summer season of 2003/04, the 20th Chinese National Antarctica Research Expedition (CHINARE) cooperated with Australian National Antarctica Research Expedition (ANARE) visited the Amery Ice Shelf again, 5 GPS sites were reoccupied. The GPS data were processed using the GAMIT/GLOBK software, and the surface ice velocities was calculated. Results show that surface horizontal velocities at the 5 GPS sites at the front of the Amery Ice Shelf vary between 900m/y and 1600m/y. Such studies are fundamental to improving our knowledge of the Antarctic ice sheet mass balance and dynamical models of ice/ocean interaction.
Software GPS receiver on micro-platform of satellite
Xiaochun Gong, Guodong Xu
The micro-platform of satellite, which is called General Cell (GC), is introduced in this paper. GC involves two important facets: First, make use of system on a chip (SoC) technology to implement high-density on board computer (OBC) design, and integrate the OBC, attitude control system (ACS), other subsystems to construct a general platform; Second, software design substituting for hardware design is prevalent ideology in system design. Because this micro-platform helps to implement spatial localization and time comparison, this system embodies a software GPS receiver. Based on description of GC, this paper developed a set of FPGA-SoC, which is integrative design of digital and analog, hardware and software. It is 270×215×25 mm3, and dry mass is 570g. With software GPS receiver, this paper discusses time synchronization problem of distributed satellite system.
An improved majority voting algorithm and its application in GPS-based precise orbit determination of LEOs
Bao-min Han, Yuan-xi Yang, Xiuying Zhu
Precise Orbit Determination (POD) of Low Earth Orbiter satellites (LEOs) based on Point Positioning (PPP) technique utilizing dual-frequency spaceborne GPS observations has become one of the best POD methods at present. Quality control of raw spaceborne GPS observations is very complex but critical for achieving high orbiting accuracy. Among the various existing methods for detecting outliers, the majority-voting algorithm used in Bernese 5.0 is a very efficient one. However, the performance of this algorithm may be affected by choice of the input parameters such as standard deviation for arranging the observations into groups, standard deviation for setting the rejection threshold and factors α and β whose values are often manually selected by experience. If the threshold is set too high, the relatively small outliers might not be found; on the contrary, more observations might be excluded and no solution could be computed for a particular epoch if the number of satellites per epoch is set to be smaller than 4. To overcome these limitations, this paper presents an improved majority-voting algorithm, which determines the some options by iteration instead of manual selection, and utilizes QUasi-Accurate Detection of outliers (QUAD) to correct the marked observations by this algorithm. The determined orbit of LEO using this new algorithm is continuous and smooth. Therefore, the improved majority voting is feasible and efficient.
A study of GPS/Galileo performance in urban environment using a simulation tool
Falin Wu, Kefei Zhang, Gang-Jun Liu
With the rapid development of spatial satellite-based infrastructure in US, Europe, Japan, China and India, there is no doubt that the next generation Global Navigation Satellite Systems (GNSS) will significantly improve the integrity, accuracy, reliability and availability of the position solution. GNSS is becoming an essential element of personal, commercial and public infrastructure and consequently part of our daily lives. However, the applicability of GNSS in supporting a range of location-sensitive applications such as location based services in an urban environment is severely curtailed by the interference of the three-dimensional urban settings. To characterize and gain in-depth understanding of such interferences and to be able to provide location-based optimization alternatives, a high-fidelity three-dimensional urban model is built with large scale high-resolution spatial data sets. The model is then used to support a comprehensive simulation study of current and future GNSS performance, in terms of availability, strength, geometry, positioning accuracy and reliability based on a number of scenarios. Useful time-stamped spatial patterns of the signal performance over the experimental area have been revealed which are very valuable for supporting location based services applications, such as emergency responses, the optimisation of wireless communication infrastructures and car navigation services.
GPS/IMU/DMI integrated high-precision positioning approach
XueXian Geng, Qingquan Li, ZhongChao Shi
This paper presents a new method for improving the accuracy of GPS/IMU/DMI integrated high-precision positioning system mounted on land vehicles. The system comprises a Position and Orientation System (POS) Computer System, an Inertial Measurement Unit (IMU), a Distance Measuring Indicator (DMI) and two Global Positioning System (GPS) antenna. The system provides continuous and accurate vehicle position and orientation information through areas of poor or no Global Positioning System (GPS) service. The relation among vehicle frame, reference frame, IMU frame and DMI frame are very important, a GPS/IMU/DMI integrated high-precision positioning approach is introduced in this paper to efficiently measure and calibrate these relations in order to improve the precision of system. Accurate measurements of the position parameters are necessary to ensure optimum GPS/IMU/DMI integrated position performance. At first, paper introduces several professional nouns, then brings forward Seven sets of parameters should be measure in this system. At last, a testing Vehicle has been designed to testing the availability, feasibility, and veracity of system. The result indicate that we can improve the precision of GPS/IMU/DMI integrated high-precision positioning system not only through ameliorating arithmetic, but also using system project idea.
Deformation extraction and its analysis based on wavelet transform
Yongqiang Huang, Jianping Wan, Jiasheng Zhang
Explanation of deformation results is crucial to obtain deformation mechanism. So far, various kinds of math models for modeling or prediction of deformation information are obtained. Each model shows its merit and demerit. For example, Auto Regressive (AR), Moving Average (MA) or ARMA is fit for modeling or prediction, but it is hard to obtain deformation mechanism from it. Wavelet transform that is the result of contemporary mathematics development has shown great role in information extraction and identification. It is 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. We start from introduction on wavelet transform to some engineering application and analysis. 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.
Mobile GIS Technology
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A mobile agent-based moving objects indexing algorithm in location based service
Zhixiang Fang, Qingquan Li, Hong Xu
This paper will extends the advantages of location based service, specifically using their ability to management and indexing the positions of moving object, Moreover with this objective in mind, a mobile agent-based moving objects indexing algorithm is proposed in this paper to efficiently process indexing request and acclimatize itself to limitation of location based service environment. The prominent feature of this structure is viewing moving object's behavior as the mobile agent's span, the unique mapping between the geographical position of moving objects and span point of mobile agent is built to maintain the close relationship of them, and is significant clue for mobile agent-based moving objects indexing to tracking moving objects.
Implementing an SIG based platform of application and service for city spatial information in Shanghai
Bailang Yu, Jianping Wu
Spatial Information Grid (SIG) is an infrastructure that has the ability to provide the services for spatial information according to users' needs by means of collecting, sharing, organizing and processing the massive distributed spatial information resources. This paper presents the architecture, technologies and implementation of the Shanghai City Spatial Information Application and Service System, a SIG based platform, which is an integrated platform that serves for administration, planning, construction and development of the city. In the System, there are ten categories of spatial information resources, including city planning, land-use, real estate, river system, transportation, municipal facility construction, environment protection, sanitation, urban afforestation and basic geographic information data. In addition, spatial information processing services are offered as a means of GIS Web Services. The resources and services are all distributed in different web-based nodes. A single database is created to store the metadata of all the spatial information. A portal site is published as the main user interface of the System. There are three main functions in the portal site. First, users can search the metadata and consequently acquire the distributed data by using the searching results. Second, some spatial processing web applications that developed with GIS Web Services, such as file format conversion, spatial coordinate transfer, cartographic generalization and spatial analysis etc, are offered to use. Third, GIS Web Services currently available in the System can be searched and new ones can be registered. The System has been working efficiently in Shanghai Government Network since 2005.
Refining the 3D building model from ground view images and 2D vectorgraph
Y. Ding, J. Q. Zhang
3D Building modeling is the focus of the research on the theory and framework of "Digital City". The more exact of the geometrical modeling and clear of the texture mapping, the more real of the building model. In this paper, we experiment on the window, apply strict geometric constraint to match line segments across images to rapidly find out the corresponding line segments in the sequential images, reconstruct the model of windows rapidly and exactly, renew the building model vivider.
A multi-tier data model for bus transit and its applications in Chinese cities
Due to the phenomenon of route overlapping, issues with bus transit have never been easily handled. For transit models and transit trip guidance, accurate quantitative data have to be retrieved from transit database. The appropriate representation of bus transit entities is of key importance in these tasks. The simple route-stop bus data model is efficient at the macro level and has been applied in many transport-related applications. However, a more comprehensive data model is needed to cope with different levels of needs as well as complicated situations existing in heavily bus-oriented cities. A multi-tier, object-oriented bus data model is developed in response to these requirements. The multi-tier data model puts transit features under one unified framework, which facilitates multi-scale applications of bus transit system.
Design and implementation of a cartographic client application for mobile devices using SVG Tiny and J2ME
L. Hui, F.-J. Behr, D. Schröder
The dissemination of digital geospatial data is available now on mobile devices such as PDAs (personal digital assistants) and smart-phones etc. The mobile devices which support J2ME (Java 2 Micro Edition) offer users and developers one open interface, which they can use to develop or download the software according their own demands. Currently WMS (Web Map Service) can afford not only traditional raster image, but also the vector image. SVGT (Scalable Vector Graphics Tiny) is one subset of SVG (Scalable Vector Graphics) and because of its precise vector information, original styling and small file size, SVGT format is fitting well for the geographic mapping purpose, especially for the mobile devices which has bandwidth net connection limitation. This paper describes the development of a cartographic client for the mobile devices, using SVGT and J2ME technology. Mobile device will be simulated on the desktop computer for a series of testing with WMS, for example, send request and get the responding data from WMS and then display both vector and raster format image. Analyzing and designing of System structure such as user interface and code structure are discussed, the limitation of mobile device should be taken into consideration for this applications. The parsing of XML document which is received from WMS after the GetCapabilities request and the visual realization of SVGT and PNG (Portable Network Graphics) image are important issues in codes' writing. At last the client was tested on Nokia S40/60 mobile phone successfully.
Computation and matching of road segment velocity with floating car data and its Web publication based on spatial road network
Yeming Fan, Chun Liu
With the improvement of road condition, traffic control and traffic information services become more and more popular and necessary. The accurate raw data of traffic situation is vital precondition for traffic decision-making. Intelligent transportation system is the certain outcome when the modern traffic system develops to a high degree. In intelligent transportation systems, real-time transportation information can be collected by Floating Car Data (FCD). In this situation, positions of a sufficient number of vehicles can be frequently sent to the center site and travel time can be measured directly. The traffic center gathers all FCD to realize traffic pattern recognition and then the recognition sets are sent by broadcast. Users can receive this information by wireless implements for dynamic navigation. In this paper, coordinate transformation of FCD, map-matching method and road segment velocity considering FCD and traffic information publication are discussed. To verify the feasibility of these methods, they are applied in a case study and prototype for Urban Transport Simulation System and certain experiment results are obtained.
Applied research on mobile GIS of off-line system architecture
Fenglin Guo, Peng Hu, Jianguo Sun, et al.
This paper defines Mobile GIS of off-line system architecture and describes its main features. Because intelligent mobile terminals do not have powerful and professional spatial database system supported, one kind of practical spatial database structure of off-line mobile GIS is proposed. Algorithms of some kernel technologies are improved according to the features of intelligent mobile terminals. In order to verify the reasonableness of spatial data organization and the validity of the improved algorithms, mNav project is implemented and we show how the applied technologies influence the whole system performance.
Application research on temporal GIS in the transportation information management system
Wei Wang, Qianqing Qin, Chao Wang
The application, development and key matters of applying spatio-temporal GIS to traffic information management system are discussed in this paper by introducing the development of spatio-temporal database, current models of spatio-temporal data, traits of traffic information management system. This paper proposes a method of organizing spatio-temporal data taking road object changes into consideration, and describes its data structure in 3 aspects, including structure of spatio-temporal object, organizing method spatio-temporal data and storage means of spatio-temporal data. Trying to manage types of spatio-temporal data involved in traffic system, such as road information, river information, railway information, social and economical data, and etc, uniformly, efficiently and with low redundancy.
Research and implementation of geography service bus in spatial data sharing platform
Zhiqiang Zou, Jiang Nan, Tao Lin, et al.
Geographic Information Systems, GIS, software has wide applications in business; however, implementation of the interoperability among the GIS has also become a challenge. This paper presents a solution based on Geography Service Bus that uses web services to achieve the interoperability among these heterogeneous GIS to allow users share the Geosciences data as well as access service. Referring to the abstract specification of OWS (OGC Web Services), the proposed solution adopts the SOA (Service-Oriented Architecture) when implementing SDSP (Spatial Data Sharing Platform). To accomplish this, a new abstract layer, GSB (Geography Service Bus), is created to provide standard interface. GSB extends ESB (Enterprise Service Bus) proposed by IBM and SUN, and combines the application in geography. GSB inherits the general features of ESB, such as interoperability, heterogeneity and service-oriented while offering unique functions like the high volume geo-data access and better management in geographic services. GSB includes the following JAVA implemented components: the management component of the geography registry service, the route component of the geography request service and the geographical business process component, etc. GSB plays an important role in SDSP and has been developed and successfully applied in the Data Center for Resources & Environmental Sciences in East China as a key project of Chinese Academy of Sciences. It has been observed that the introduction of GSB has tremendously improved both performance and interoperability of SDSP among heterogeneous GIS than traditional methods.
Mobile GIS solution applying dynamic data file and automatic update engine
Xin Zhang, Yue-feng Liu
With the rapid development of the computer hardware, software and the network technology, a great deal of multimedia contents including graphics and images can be displayed on the mobile device like mobile phone, PDA and vehicle equipped terminals. In this paper, we put forward the concepts of dynamic data file and automatic update engine, which are both applied in our mobile GIS architecture. The former are used to supply information for local query, the latter updates the former when necessary. By this mechanism, we reduce the network transfer frequency to minimum, raise the efficiency and fully utilize the computing capacity of the mobile device and application server in the mean time.
An efficient method for transformation between QTM codes and geographic coordinates
Xuesheng Zhao, Jun Chen, Zhilin Li
QTM (Quaternary Triangular Mesh) on spherical surface is an efficient structure for managing the large volume of global spatial data. But the existing methods for the transformation between QTM Codes and Longitude/Latitude Coordinates are either not very efficient or lacking of orientation information in encoding scheme which is very useful in the adjacent query. To overcome these serious deficiencies, a new method is developed for transformation between long\latitude and QTM address codes. This method is simply called Row & Column Approach, or simply RCA. This method is a simple method without any map projection and it recursively approaches the address codes according to orientation information. Experimental evaluation shows that this method is much more efficient than the ETP (Equilateral Triangular Projection), i.e. only about 18% (conversion from longitude/latitude to address code) and 33% (conversion from address code to longitude/latitude) of time required by ETP.
A spatial indexing approach based on linear referencing system
Xiao qing Zuo, Yuan min Fang
To 3D visualization of terrain data with large ranges, we often use the strategy as follows: terrain model is firstly divided into regular patches and then index mechanism is set up on the basis of data patches. Next, we load batches of data patches around the viewpoint dynamically. However, when many road networks are nested into terrain models, it is difficult for terrain models to divide into regular patches in an original way. It is well known that the data is along the road in a linear way and the roads connect to each other. According to the above feature, a hybrid index mechanism combining connectivity with dynamic segmentation is proposed in this paper, which can realize the process of query in two steps. The first step is to search roughly by means of connectivity index. Based on the results of the first step, the second step can finish the process of exact query satisfactorily using dynamic segmentation index. This index mechanism with high query speed guarantees speed of loading data dynamically, and meets the demand of visualization of road network. Finally, we implement the algorithm by means of some experiments, and give a comparison in space efficiency and time efficiency with R-tree index.
Design and implementation of distributed multimedia surveillance system based on object-oriented middleware
Xuesong Cao, Ling Jiang, Ruimin Hu
Currently, the applications of surveillance system have been increasingly widespread. But there are few surveillance platforms that can meet the requirement of large-scale, cross-regional, and flexible surveillance business. In the paper, we present a distributed surveillance system platform to improve safety and security of the society. The system is constructed by an object-oriented middleware called as Internet Communications Engine (ICE). This middleware helps our platform to integrate a lot of surveillance resource of the society and accommodate diverse range of surveillance industry requirements. In the follow sections, we will describe in detail the design concepts of system and introduce traits of ICE.
An approach for traffic prohibition sign detection
Qingquan Li, Dihong Xu, Bijun Li, et al.
This paper presents an off-line traffic prohibition sign detection approach, whose core is based on combination with the color feature of traffic prohibition signs, shape feature and degree of circularity. Matlab-Image-processing toolbox is used for this purpose. In order to reduce the computational cost, a pre-processing of the image is applied before the core. Then, we employ the obvious redness attribute of prohibition signs to coarsely eliminate the non-redness image in the input data. Again, a edge-detection operator, Canny edge detector, is applied to extract the potential edge. Finally, Degree of circularity is used to verdict the traffic prohibition sign. Experimental results show that our systems offer satisfactory performance.
A spatial reference frame model of Beijing based on spatial cognitive experiment
Jie Zhang, Jing Zhang, Yu Liu
Orientation relation in the spatial relation is very important in GIS. People can obtain orientation information by making use of map reading and the cognition of the surrounding environment, and then create the spatial reference frame. City is a kind of special spatial environment, a person with life experiences has some spatial knowledge about the city where he or she lives in. Based on the spatial knowledge of the city environment, people can position, navigate and understand the meaning embodied in the environment correctly. Beijing as a real geographic space, its layout is very special and can form a kind of new spatial reference frame. Based on the characteristics of the layout of Beijing city, this paper will introduce a new spatial reference frame of Beijing and use two psychological experiments to validate its cognitive plausibility.
Research on the key technologies of mobile digital maps
Cuiling Ji, Yongkang Xiao, Tianhe Chi
Mobile and wireless technologies have evolved rapidly in recent years, especially the development of hardware devices, such as PDA and Smart phone. Different kinds of services and applications in these mobile devices, especially Mobile Geographic Information System and Location Based Service have been launched in recent years to help people to establish spatial relationship with the surroundings. Digital Map, which is a useful tool to assist a person for positioning and navigation, is usually included in these services. However, mobility of wireless devices, limited bandwidth of wireless networks, and limited storage capacity of mobile terminals seriously affect the performance of mobile digital maps and its application. In order to boom its application in mobile devices, this paper focuses on four important problems, i.e., data model optimization of mobile digital map, data organization and management at server side and client side respectively, data compression method, representation approaches on mobile terminals. In this paper, we adopt and modify the Europe transportation network standard GDF, accomplish effectively data compression with SVG, and present a new two-layer database structure to organize data. The digital maps can be expressed by multi-approaches, namely layers, districts and scales.
Implementing computing techniques to accelerate network GIS
Chaowei Phil Yang, David Wong, Menas Kafatos, et al.
We have witnessed the accumulation of petabyes of geospatial data in the past decades, and, currently, terabytes of data are collected every day. These geospatial data are crucial in supporting decision making and emergency response. It becomes increasingly important to deliver these datasets in a timely fashion to the decision support or emergency response systems. Network GIS provides a vehicle to facilitate this delivering process. But to deliver efficiently such large volume of data and to handle large number of concurrent users, the performance of Network GIS needs to be improved to a level that different types of applications, especially near real time applications, can be satisfied. In this circumstance, we 1) review selected research on improving the performance of Network GIs; 2) provide insides on implementing the techniques; and 3) illustrate how to adopt the techniques in Network GIs. We expect the research and development reported here can be easily adopted by different users to accelerate the performance of various Network GIS software and applications, as well as to support the building of spatial data infrastructure to support the sharing of heterogeneous geospatial information.
Resources Management
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Exploitation potential evaluation on region shallow groundwater with support of GIS
Fucun Zhang, Xiuju Yao, Xufeng Li, et al.
Taking the Yellow Rive Delta as example, this paper discusses the establishment of potential assessment model for region shallow groundwater development based on GIS technology, and accesses the exploitation potential in the Yellow River Delta. The comprehensive evaluation model considers five factors, i.e. groundwater recharge, aquifer characteristic, groundwater quality, groundwater exploitation intensity and land use. According to the authors set up the basic data respectively. Then using weighted summation assessment model and spacial superposition function of GIS, they built the evaluation results of five influencing factors above (middle layer) . Finally obtained a clear map of exploitation potential districts of shallow groundwater in the Yellow Rive Delta with weighted calculation and superposition calculation of space datum. Groundwater recharge considered four factors, i.g. amount of precipitation, buried depth of groundwater level, lithologic character of aeration zone and surface drainage system; aquifer characteristic considered storability of free water and transmissivity; Groundwater quality only considered total salinity; groundwater exploitation intensity was the ratio that exploitable groundwater was divided by practical exploitation of groundwater; land use considered four factors, i.g. farmland, alkaline land, salt lick and other use type of land. Weight of evaluation factors was calculated by Analyzing Hierarchy Process(AHP) and expert evaluation method. First formed a judge matrix, then proved randomicity and consistency of the judge matrix. As a result, the assessment results were divided into five grade districts: most potential, potential, relative potential, short potential and non-potential.
Dynamic monitoring of the built-up area expansion of Hong Kong based on remote sensing and the driving mechanism analysis
Fengyun Mu, Zengxiang Zhang, Changyou Wang, et al.
The urban space expansion is an important indicator for measuring urbanization level. Based on one Landsat MSS image and three Landsat TM images, the urban built-up characteristic of Hong Kong and its impact on the peripheral land during1973-2004 was analyzed. The urban area was 59.95km2 in 1973 and increased to 207.70km2 in 2004, the built-up area increased by 147.75km2 during the past 31 years and expanded 4.77km2 per year. The built-up area expanded around the old area and didn't present manifest change in a certain direction. The expansion rate was distinct from each other and Beijing city experienced two fast expansion stages comparatively. The increased built-up area originates from different land use type, of which about 33.28% converted from sea, and 13.34% converted from rural area and dependent factory, diggings land and other construction area. The other mainly came from arable that accounts for 39.93% of the whole added built-up area. Many factors have contributed to the urban land use changes. But four major driving forces, population growth, economic increase, transportation infrastructure improvement and institution and policy change, are the most important factors. Population growth can simulate the built-up area manifestly, the economic increase is the main impetus of the land use, and the transportation infrastructure improvement is the impetus for the urban expansion, while the institution and policy change determine the macroscopical development and expansion pattern in some degree.
Effect of coal mining on regional ecological footprint based on GIS
Qiu-ji Chen, Yun-feng Kong, Hong-bo Zhang
Coal mining has brought a plenty of benefit and matter for human kind, and greatly improved the development of economy and society. At the same time, however, it has also lead to the environment damage, which has affected the regional sustainable development. In this paper, we take the Luxi Coal Mine, Shandong Province as an example, based on the GIS, to study the effect on the sustainable development due to coal mining with the theory of ecological footprint. The research result show that coal mining inevitably affects the ecological footprint of coal mining area. In order to minimize the ecological deficit, measures shall be taken during coal mining period to reduce the environment damage by coal mining, adopting new reclamation method to protect the ecological producing land and avoiding cultivated land degraded.
Research and implementation of mining GIS software for unstratified mineral deposit
Mei Li, Yajing Liu, Shanjun Mao
In this paper, a professional mining GIS software called Geological and Surveying Spatial Management Information System (GSSMIS) was designed and implemented. Due to restriction of mine design and computerization level, geostatistics and 3D block model were not fully applied in metal mining. The geologists interpreted drill holes and delimit mineral boundaries on the 2D plane and section. Unlike other 3D mining software, a 2D & 3D integration technological architecture for unstratified mineral deposit was proposed considering the conventional exploration and exploitation approaches. The whole system contains 3 modules: geological and surveying database module, 2D MGIS module and 3D modeling and visualization module. Database module input, manage, store and extract all kinds of geological and surveying data. 2D MGIS module provide lots of toolbox for plotting all sorts of engineering maps and processing advance analysis such as geostatistical and uncertain analysis, reserve computation and mining economic estimation. GSSMIS has a typical COM GIS configuration with 5 different developing levels. The 5 level structure has advantage of less coding, easier maintenance and management, good ability of extension and secondary development, adding or subtracting the modules according to user's need. Also, 5 important system characters were introduced in the article, which were: 1) 2D auto-mapping; 2) interactive interpretation of geological boundaries; 3) mutual modifications of plane and section; 4) 3D solid modeling; 5) section profile cutting. Finally, the article presented the implement of GSSMIS in Laixin Iron, Shandong Province. The system changed traditional handcraft mapping mode thoroughly, relieved the heavy burden of engineers and promoted the process of computerization and informatization in China.
Study of general land use planning by means of SD-MOP integrated model
Jian Gong, Yaolin Liu, Zhi Zhang, et al.
General land use planning is the sticking point of the land resource management. As the chief means of conservative use for the land resources and macroeconomic control for the national economy, it plays an important role in Chinese land resource management. In the paper, the author firstly generalizes the deficiency of the current methods of general land use planning in China, and puts forward a way for general land use planning basing on the SD-MOP Integrated Model. Secondly, the author takes Hangpi country of Wuhan city for example and studies carefully the construction model, the parametric estimation and factors' identification and optimization. Through the model simulation run and result analysis, the author also prospect application of SD-MOP Integrated Model in land use planning, which is regarded as a new method for the project study of general land use planning.
Application of RS-based multivariate geological information for mineral resources prediction in vegetation zones
Zhifang Zhao, Jianping Chen, Jian Bai, et al.
To get a sound method for mineral prediction in dense vegetation zones, this study applies RS and GIS technologies to predict mineral resources in Genma and Cangyuan of Yunnan, P.R.C., where mineralization is concentrative but little breakthrough is achieved in exploring mineral deposits resulting from dense vegetation covers. Methods on the geological application of RS in dense vegetation zones are developed in the study, and practically proven to be effective. Based on GIS, mineralization and alteration indicators for vegetation zones are formulated by applying the ETM RS multi-functional image processing techniques. Along with RS-based multivariate geological indicators, geological, geophysical and geochemical data are integrated and used to construct quantitative models for mineral resources prediction and assessment using Information Quantification Method. Based on the models, mineral deposits are digitally predicted, and accordingly information on deposit formation and control is effectively derived and optimized. The information is verified through all-around field surveys in the target areas, and satisfactory results are obtained. Hence, the techniques and methods in the study are worthy of extension.
Directional vegetation index and its effects on normalized-difference-vegetation-index-based agricultural applications
Jun-hui Chen, Peng-xin Wang, Wei Sun, et al.
The directional normalized difference vegetation index (NDVI) was calculated by using field measured spectral data of the winter wheat canopies at the crop different growth and development stages. In the principal plane, the hotspot and directional NDVI were analyzed. The relationships between NDVI and leaf area index (LAI) were developed, and the effects of the directionality on vegetation index based applications were discussed as well. Considering the reflectance changes near the hotspot for the two winter wheat cultivars which have a horizontal leaf type and an erectile leaf type, respectively, we find spectral reflectances of the red and near-infrared bands at the hotspot are slightly higher than those near the hotspot. However, NDVI at the hotspot is significantly lower than that near the hotspot. The regression analysis results between NDVI and LAI show that there are significant exponent correlations between directional NDVI and LAI for the two cultivars. However, the coefficients of the exponent equations and the correlation coefficients are varied with the viewing zenith angles, and the correlation coefficients for the two wheat canopy types are also varied at a given viewing angle. These results indicate the directionality of NDVI should be considered for NDVI based agricultural applications.
Study on application of dynamic monitoring of land use based on mobile GIS technology
Jingyi Tian, Jian Chu, Jianxing Guo, et al.
The land use dynamic monitoring is an important mean to maintain the real-time update of the land use data. Mobile GIS technology integrates GIS, GPS and Internet. It can update the historic al data in real time with site-collected data and realize the data update in large scale with high precision. The Monitoring methods on the land use change data with the mobile GIS technology were discussed. Mobile terminal of mobile GIS has self-developed for this study with GPS-25 OEM and notebook computer. The RTD (real-time difference) operation mode is selected. Mobile GIS system of dynamic monitoring of land use have developed with Visual C++ as operation platform, MapObjects control as graphic platform and MSCmm control as communication platform, which realizes organic integration of GPS, GPRS and GIS. This system has such following basic functions as data processing, graphic display, graphic editing, attribute query and navigation. Qinhuangdao city was selected as the experiential area. Shown by the study result, the mobile GIS integration system of dynamic monitoring of land use developed by this study has practical application value.
Study on dynamic change of wetlands in Yellow River Estuary based on remote sensing and GIS technology
Hui Sheng, Jianhua Wan, Shoujing Yin, et al.
Based on Remote Sensing and Geographical Technique, we have analyzed the situation and changes of the Land Cover/Use in Yellow River Delta Wetland and evaluated the changed information by means of sight analyzing. Then the change drives are concluded and some suggestions are provided for the reasonable use and protection of Yellow River Delta Wetland.
SWOTs methodology for digital urban planning
Wei Wei, Gu-yi Liu
From the concept of digital urban planning method, using the SWOTs state methodology, the article analyzes the contents and strengths that digital technique used in urban planning drawing up, analyzes the weaknesses and limitations that GIS technique used in urban planning. Combined the characteristics of information society and digital city, analyzes the historic opportunity for urban planning brought by the digital technique. At last, combined the practical conditions of China's urban planning field, expresses the huge threats that the digital urban planning is facing with.
Research of integration for coastal belt multi-source spatial data
Jinglei Zhang, Weian Wang, Gang Qiao
To meet the need of the research and application of topographic changes on coastal belt, multi-source data of coastal belt, which are spatial and non-spatial, are collected, analyzed and managed. Ideas and methods on the integration of multiple sources spatial data, coming from GIS, RS and GPS, are briefly expatiated based on the work just mentioned and have been verified theoretic correctness and practical feasibility. The organization method of spatial information based on ArcSDE is efficient and adaptive to integration of multi-source. What we have done makes for the implementation of establishment of coastal belt database by Oracle and the study of data mining on the topographic changes of coastal belt.
A global-view-oriented approach to directory management in distributed spatial database
Zhou Huang, Yu Fang, Bin Chen, et al.
Based on discussion on general methods of constructing global directory in DSMDS (Distributed Spatial Database Management System), a new approach based on relation model was brought forward. It specifies three main components of the global directory, including directory organization, directory update and extern interface. Then the authors implemented an actual global directory named SDirectoryService as well, key approaches and techniques in implementation were discussed in detail. Some experiments were designed and performed to check the efficiency, correctness and feasibility of the global directory, which reveal the directory works well on each aspect. By using the directory effective global query processing was achieved in DSMDS.
Research on image evidence in land supervision and GIS management
Qiu Li, Lixin Wu
Land resource development and utilization brings many problems. The numbers, the scale and volume of illegal land use cases are on the increasing. Since the territory is vast, and the land violations are concealment, it is difficulty for an effective land supervision and management. In this paper, the concepts of evidence, and preservation of evidence were described first. The concepts of image evidence (IE), natural evidence (NE), natural preservation of evidence (NPE), general preservation of evidence (GPE) were proposed based on the characteristics of remote sensing image (RSI) which has a characteristic of objectiveness, truthfulness, high spatial resolution, more information included. Using MapObjects and Visual Basic 6.0, under the Access management to implement the conjunction of spatial vector database and attribute data table; taking RSI as the data sources and background layer; combining the powerful management of geographic information system (GIS) for spatial data, and visual analysis, a land supervision and GIS management system was design and implemented based on NPE. The practical use in Beijing shows that the system is running well, and solved some problems in land supervision and management.
A global map of rainfed cropland areas at the end of last millennium using remote sensing and geospatial techniques
C. M. Biradar, P. S. Thenkabail, H. Turral, et al.
Rainfed agriculture plays a critical role in most part of the tropics and subtropics of the world. Eighty percent of the agricultural land worldwide is under rainfed agriculture; and significant proportion of rural economy still depends on rainfed agriculture with characteristically low yield levels. In this context the International Water Management Institute (IWMI) produced the first satellite sensor based Global map of rainfed cropland areas at 10Km resolution (GMRCA10Km). The study used a mega-file of 159 global data layers involving the AVHRR and SPOT time-series, GTOPO30 DEM, mean monthly rainfall, and forest cover. A suite of innovative techniques were developed that begins with the image segmentation, quantitative spectral matching techniques (SMTs) and spectral correlation similarity (SCS R2). The SCS was found to be the most useful technique in grouping identical classes. Mixed classes were resolved using a decision trees, time series plots, and principal component analysis algorithms. A wide array of groundtruth data, and high-resolution images were used to identify and label classes. The outcome was the GMRCA10Km estimated to be 1.75 billion hectares for the main cropping period. The sub-pixel areas (SPAs) of GMRCA10Km provide more realistic estimates of the actual area cultivated unlike the full pixel areas (FPAs) often calculated from the raster datasets. Three distinct GMRCA10Km maps have been produced: viz., Aggregated 7-class, Dis-aggregated 18-class and Generic 255-class. The aggregated classes will suffice for broad range of users at global level. The GMRCA10Km product line consists of maps, images, area calculations, snap-shots, class characteristics, and animations.
International Water Management Institute's Data Storehouse Pathway (IWMIDSP): a unique data and knowledge gateway of spatial data with emphasis on river basins
Prasad S. Thenkabail, Chandrashekhar Biradar, Praveen Noojipady, et al.
The International Water Management Institute's Data and Knowledge Storehouse Pathway (IWMIDSP) was launched in June 2004 meeting the need identified in the IWMI 2002-2004 MTP Project 1: "Improved tools for assessment, accounting, planning and use of water resources for agriculture and food production." Since then to now, IWMIDSP (http://www.iwmidsp.org) has evolved as a pathfinder in providing over 3 terabyte of state-of-art value added remote sensing and GIS (RS/GIS) data and products of high scientific quality that are made available through online access for the global benchmark river basins, Nations, regions, and the entire World. The IWMIDSP has about 5 new registrations every day and currently (as on February 16, 2006) reaching a total permanent registrations of 1964 from over 50 Countries. Over last 1-year there has been, on an average, a constant stream of at least 2000 visitors from 70 Countries every month. To date, about 1.4 million hits have been recorded, 270,000 pages visited, and on an average 130 gigabytes of data downloaded every month. All data in IWMIDSP have accompanied by Meta data at international standard (FGDC). Our data users include students from leading Universities of the World, researchers from UN organizations, USGS, NASA, and National Institutions. Further the IWMIDSP link has been provided by over 50 web portals. The site has also been profiled by the World Health Organization, UN Human Settlement Program (UN HABITAT), and UN Economic Commission for Africa (UNECA). The IWMIDSP generated maps were widely used to understand and inform Tsunami damage and rehabilitation immediately after Tsunami by the coordinating National Office (CNO)-a Sri Lankan Presidential initiative (http://www.iwmidsp.org/iwmi/info/tsunami.asp). IWMIDSP hosted and disseminated real time Tsunami Response maps of Sri Lanka (an effort of IWMI and MapAction UK) to the world. These maps were not only popular with the non-Governmental Organizations (NGO's) working in Sri Lanka, but were printed in a book (FAO, 2005) by FAO (www.fao.org/tsunami/environment/maps.html). The maps were also used in the "Geographic Information Systems" chapter in an Australian school book (Easton et al., 2006) of which 40,000 copies were printed. The IWMIDSP data is instrumental in production of the first satellite sensor based Global Map of Irrigated Areas (GMIA; http://www.iwmigiam.org) and the South West Asia drought monitoring project (dms.iwmi.org). The IWMIDSP has been hailed as the "best UN or similar GIS sites I have seen" by Keith Forbes of UN Economic Affairs Officer. Dr. John G. Lyon, Director of USEPA Las Vegas writes: "I just cant say enough positive things about the site....what is very striking to me, is...this is probably the very first time that all these great sources of data and information and decision support systems have made all their great work available free of charge and in formats that all can understand....it is truly impressive...." The outcome is that IWMIDSP has established itself as a unique one of its kind Global Public Good (GPG) data and knowledge spatial data gateway.
Water quality monitoring model construction by integration of multi-source data: a case study in Whangpoo River upper region
Huan Xie, Xiao-hua Tong, Yan-ling Qiu, et al.
The method by the integration of multi-source data including remote sensing data, ground spectral measurement data and other in situ monitoring data, is presented in this paper to construct a quantitative water quality inversion model. The upper region of Whangpoo River in Shanghai is selected as a study area and the dissolved oxygen is chose as a typical water quality indicator. We first process the remote sensing imagery and field spectrometer data to obtain the accurate water reflectance. An inversion model of dissolved oxygen is then derived from the modeling analysis between the water quality data and the reflectance. The accuracy of the model is further confirmed, and this model is applied to invert the dissolved oxygen distribution in Whangpoo River upper region. The inverted water quality distribution has a high consistency with the practical case. This proves that the method by integration of multi-source data is an effective way to monitor the water quality.
Analyses and simulation to spatial pattern of land utilization in Guangzhu City
Xin-chang Zhang, Wen-jiang Zhang, Kun Ma
Based on Landsat TM remote sensing images in 1990 and 2000, we analyses the temporal and spatial pattern Characters of land use in the 1990s in Guangzhou city. We also simulate the scenarios of land-use pattern in 2010 by integrating the Markov process into cellular automata model. The results show that the area of constructions was rapid increasing during the last ten years of the 20th century, at the same time the arable land, woodland and unused land areas were decreasing, the orchard and water areas were rarely changed; In the first ten years of 21st century, land use pattern keep the change trend in the 1990s, land of constructions continue rapid increasing; arable land and unused land areas continue rapid decreasing; woodland, orchard and water areas keep steadily. Research shows that the extent of urban area has increased exponentially in Guangzhou city, no evidences show that the arable land decreasing rate will slow down in the near future. So, it is necessary to enhance the control functions of land use planning and take actives measures to protect arable land.