In this paper we describe an emotional-behvioral architecture. The emotional engine sits at a higher layer than the behavior system, and can alter behavior patterns, the engine is designed to simulate Emotionally-Intelligent Agents in a Virtual Environment, where each agent senses its own emotions, and other creature emotions through a virtual smell sensor; senses obstacles and other moving creatures in the environment and reacts to them. The architecture consists of an emotion engine, behavior synthesis system, a motor layer and a library of sensors.

Traditionally, three dimension models have been used for building virtual worlds, and a data structure called the "scene graph" is often employed to organize these 3D objects in the virtual space. On the other hand, image-based rendering has recently been suggested as a probable alternative VR platform for its photo-realism, however, due to limited interactivity, it has only been used for simple navigation systems. To combine the merits of these two approaches to object/scene representations, this paper proposes for a scene graph structure in which both 3D models and various image-based scenes/objects can be defined, traversed, and rendered together. In fact, as suggested by Shade et al., these different representations can be used as different LOD's for a given object. For instance, an object might be rendered using a 3D model at close range, a billboard at an intermediate range, and as part of an environment map at far range. The ultimate objective of this mixed platform is to breath more interactivity into the image based rendered VE's by employing 3D models as well. There are several technical challenges in devising such a platform: designing scene graph nodes for various types of image based techniques, establishing criteria for LOD/representation selection, handling their transitions, implementing appropriate interaction schemes, and correctly rendering the overall scene. Currently, we have extended the scene graph structure of the Sense8's WorldToolKit, to accommodate new node types for environment maps billboards, moving textures and sprites, "Tour-into-the-Picture" structure, and view interpolated objects. As for choosing the right LOD level, the usual viewing distance and image space criteria are used, however, the switching between the image and 3D model occurs at a distance from the user where the user starts to perceive the object's internal depth. Also, during interaction, regardless of the viewing distance, a 3D representation would be used, it if exists. Before rendering, objects are conservatively culled from the view frustum using the representation with the largest volume. Finally, we carried out experiments to verify the theoretical derivation of the switching rule and obtained positive results.

The most promising aspect of augmented reality lies in its ability to integrate the virtual world of the computer with the real world of the user. Namely, users can interact with the real world subjects and objects directly. This paper presents an experimental augmented reality system with a video see-through head-mounted device to display visual objects, as if they were lying on the table together with real objects. In order to overlay virtual objects on the real world at the right position and orientation, the accurate calibration and registration are most important. A vision-based method is used to estimate CCD external parameters by tracking 4 known points with different colors. It achieves sufficient accuracy for non-critical applications such as gaming, annotation and so on.

This paper introduces a virtually walking platform. It is a bi-arm virtual reality (VR) experimental platform supporting for natural walk, walker's walking position being kept fixed by controlling this platform. Optical PSD system is taken for tracking, and SERCOS bus technology for controlling. In addition, image-based portraying technique is taken for virtual scene. Through this set of walking platform, infinite virtual walking is preliminarily realized using finite locomotion equipment.

One of the most interesting research areas in virtual reality is how to wander freely in image-based virtual spaces. This paper presents a novel conspherical mosaics based on Concentric Mosaics. With this method, users can wander freely in image-based virtual spaces, furthermore look in all directions. We also make use of the idea of hyperlink to organize the virtual objects in virtual spaces so that users can manipulate them freely.

Various techniques for object selection in virtual environments have been proposed over the years. Among them, the virtual pointer or ray-casting is one of the most popular method for object selection because it is easy and intuitive to use and allows the user to select objects that are far away. Variants of the virtual pointer metaphor include the Aperture, Flashlight, and Image plane method as categorized as such. In a monoscopic environment, these methods are essentially 2D interaction techniques, as the selection is made effectively on the image plane. Such a 2D based selection (or more generally, interaction) method has an added advantage in that it can find many good uses in 3D environments ranging from a simple 2D oriented subtask (object selection on a constrained surface, menu selection) to a situation where a whole 2D application (e.g. sketching tool, desktop manager) is embedded in the 3D environment. In this paper, we experimentally compare the performance of four different virtual pointer implementations, namely, the direct image plane selection, head-directed pointer, hand directed pointer and head-hand directed pointer. The experimental results revealed that the direct image plane selection produced the best performance among the four in terms of both task completion time and the pixel-level pointing error.

In this paper, we combine geometry-based and image-based rendering techniques to develop a VR navigation system that aims to have efficiency relatively independent of the scene complexity. The system has two stages. In the pre-processing stage, the x-y plane of a 3D scene is partitioned into equal-sized hexagonal navigation cells. Then for each navigation cell, we associate each object outside the cell with either a LOD mesh or an object-based depth mesh depending on its self-occlusion error. The object with the error larger than a user-specified threshold is associated with a LOD mesh of an appropriate resolution. For the object with error smaller than the threshold, we associated it with a depth mesh that is reduced from its original mesh based on the silhouette and depth information of its image rendered from the cell center. All LOD meshes are then culled by a conservative back-face computation, and then all LOD and depth meshes are culled by a conservative visibility computation, all aim to remove polygons that are invisible from any point inside the cell. At run-time stage, LOD meshes are rendered normally while depth meshes are rendered by texture mapping with their cached images. Techniques for run-time back-face culling and occlusion culling can be easily included. Our experimental results have depicted fast frame rates for complex environments with an acceptable quality-loss.

Terrain visualization plays an important role in the fast growing domain of Geographic Information System (GIS) and Virtual Reality (VR). How to render terrain in real-time is a hot issue in recent years, and many algorithms of terrain refinement and simplification have appeared. In this paper, an improved terrain refinement method is represented. This algorithm is based on quadtree triangulation. We enhance the sorting and triangulating process. The algorithm adopts view dependent error metric and view frustum culling to acquire considerable better performance. By implementing the algorithm and analyzing the results from experiment, we conclude that this algorithm is practical and applicative in terrain visualization system.

Previous approaches using quadric error metric allow fast and accurate geometric simplifications of meshes, but they don't consider rendering schemes and texture contents. A newly developed framework, image-driven simplification, uses image errors to decide which portions of model to simplify. The image-driven simplification is sensitive to rendering schemes and texture contents, and can produce simplified models with better visual quality. However, it can not deal with some models with highly complex visibility. In this paper, we introduce the rendering error metric and combine it with the quadric error metric. Benefits of using rendering error metric include higher quality simplified meshes, better preserved geometric and color boundaries, and simplification that is sensitive to the content of a texture. In contrast with the original image-driven simplification algorithm, our algorithm samples the model locally per edge collapse to compute the rendering error metric and is independent of specific viewpoints, so it can deal with any kind of models, even highly self-occluded models. We demonstrate the efficiency of the algorithm with a variety of meshes with normal/color/texture attributes.

Techniques animating a kind of cloth-like objects based on mass-spring (MS) model are widely used in the real-time simulation systems. A velocity modification algorithm based on the explicit Euler integration method is firstly proposed to overcome the super-elasticity of the MS model, which effectively improves the accuracy and reality without adding extra computational complexity. Both theoretical and experimental analyses prove that the modification algorithm effectively recuperate the stability of the simple Euler method. The new technique, which blends the integration method and modification algorithm for simulating the draping behavior of a kind of flexible objects, is fast, stable accurate, and suitable for the development of 3D garment CAD system.

3D human facial model reconstruction is essential to generation of facial animations that is widely used in the field of virtual reality. The main issues of 3D facial model reconstruction based on images are in twofold: one is to track the features of face automatically and the other is to get the realistic-looking human face model. In this paper, we introduce a method on structure from motion. First the accurate corner matches can be acquired by integrating modified image pyramid Lucas-Kanade algorithm and local adjustment algorithm, then a realistic-looking model is generated by camera calibration, motion analysis and texture mapping. Experimental results demonstrate the high accuracy of the corner matching algorithm and the vividness of the facial model.

Surfaces can be generated easily by subdividing polyhedral networks recursively, but over simple or rough polyhedral network, it is difficult to get the surfaces which designers want to model. To solve this problem, complex or precise polyhedral networks have to be defined. In this paper, a set of rules and an automatic adaptive algorithm for making fillet operations with Loop subdivision are presented. The fillet operations are implemented by subdividing a polyhedral network one step with the given sharpness of edges of the polyhedral network. Generally, the number of edges that meet at one vertex is no restriction and the sharpness of every edge can be different. The fillet operations proposed here will strengthen the functions of Computer Graphics system which use subdivision surfaces to model surfaces.

Virtual object registration is one of the critical technologies in augment reality. A projection algorithm for virtual object registration, based on coordinate transition and 3D projection in 3D space, is described in detail. Combined with 3D-fidudial vision-based registration, the discussed algorithm can successfully accomplish the registration of augment reality.

This paper presents a general method for selectively refining or coarsening progressive meshes. Our method works for arbitrary meshes, deals with non-manifolds, and allows the change of manifold and genus properties of the mesh. We introduce new definitions for edge contraction and expansion operations, which make solely use of the vertex hierarchy. These definitions in conjunction with their legal conditions lead to many provable properties of the refinement process. In addition, we propose a locally re-stripping method to dynamically generate the strips during selective refinements, which efficiently forms strips for meshes coarsening or refining process.

In this paper we propose a new hierarchical 3D facial model based on anatomical knowledge that provides high fidelity for realistic facial expression animation. Like real human face, the facial model has a hierarchical biomechanical structure, incorporating a physically-based approximation to facial skin tissue, a set of anatomically-motivated facial muscle actuators and underlying skull structure. The deformable skin model has multi-layer structure to approximate different types of soft tissue. It takes into account the nonlinear stress-strain relationship of the skin and the fact that soft tissue is almost incompressible. Different types of muscle models have been developed to simulate distribution of the muscle force on the skin due to muscle contraction. By the presence of the skull model, our facial model takes advantage of both more accurate facial deformation and the consideration of facial anatomy during the interactive definition of facial muscles. Under the muscular force, the deformation of the facial skin is evaluated using numerical integration of the governing dynamic equations. The dynamic facial animation algorithm runs at interactive rate with flexible and realistic facial expressions to be generated.

Natural User Interface is one of the important next generation interactions. Computers are not just the tools of many special people or areas but for most people. Ubiquitous computing makes the world magic and more comfortable. In the design domain, current systems, which need the detail information, cannot conveniently support the conceptual design of the early phrase. Pen and paper are the natural and simple tools to use in our daily life, especially in design domain. Gestures are the useful and natural mode in the interaction of pen-based. In natural UI, gestures can be introduced and used through the similar mode to the existing resources in interaction. But the gestures always are defined beforehand without the users' intention and recognized to represent something in certain applications without being transplanted to others. We provide the gesture description language (GDL) to try to cite the useful gestures to the applications conveniently. It can be used in terms of the independent control resource such as menus or icons in applications. So we give the idea from two perspectives: one from the application-dependent point of view and the other from the application-independent point of view.

Current VR systems mainly use geometric models, which has proved to be insufficient to provide the haptic display capability needed in many applications such as surgery training. Physics based dynamic models play a crucial role in this respect, e.g. for realistic haptic display of the operating feel via Virtual Reality (VR) systems. Such physics based models are desirably obtained via experimental identification. However, traditional dynamics identification methods normally require very large sized training data sets, which maybe difficult to meet in practical applications. This paper presents a method for identifying dynamics models using Support Vector Machines (SVM) regression algorithm which is more effective than traditional methods for high dimensional sparse training data. This method can be used as a generic learning machine or as a special learning technique that can make full use of the known dynamics structure knowledge. The experimental results show the application of our method identifying friction models for realistic haptic display.

This paper describes a virtual environment system, which can produce dynamic force simulation during the control of objects in virtual environment. A 5 degrees-of-freedom haptic interface master arm with the capability to generate kinesthetic effect is combined in this system. In this system, the human operator manipulates an object in virtual environment by using the 5-DOF master arm. When virtual manipulator contacting with the virtual object, the contact force can be calculated and shown in the graphic interface. The collision response and deformation of the virtual object, which is usually called haptic rendering, also can be exhibited in graph. The experience presents an approach to improve the operator's immersion and can be used in many telerobot control fields.

The interface environment of a computer still uses a mouse and a keyboard and it is hard for many users including aged person to use computers. The computer operation may become difficult with age even if a person can use a computer currently. Development of the interface system is desired that permits persons to talk to a computer in the same way as they communicate with other ones. Of course the development of such an interface system will be effective for all computer application users in addition to aged person. We developed in this study the man machine interface system that exploits virtual reality in order to bring a talk between a person and a machine close to that between persons. We aimed at realization of bi-directional verbal/nonverbal communication that permits both the user and an avatar rendered in virtual space can use a spoken language and nonverbal behavior such as gesture/a hand gesture. As the field of concrete application, the field of assembling/disassembly of mechanical part is selected. We produced an experimental assembly training system that helps a novice acquire a right assembling procedure of virtual machine. In the system, a user can ask an avatar to show the way to assemble/disassemble mechanical parts whenever he needs help.

In this paper we present our effort towards the goal of perceptual user interface for major interaction tasks, such as navigation/travel, selection/picking and personal data access, for virtual shopping. A set of 3-D navigation devices, vision-based pointing and personal access system are mainly discussed. The motivation and design principles behind these interfaces are also described. A prototype integration solution, which bring these devices together in virtual shopping environment, is given. These interfaces and interaction devices have been implemented and tested for evaluation.

A haptic interface device has been presented for human-computer-interaction (HCI) in this paper, which uses a 6 degree-of-freedom (DOF) force sensor for six axis force and torque (F/T) measurement. With this device, the user could grasp a moveable handle to interact with simulated 3D environments in real-time for production design, simulation and predication. As a human-computer-interface device, its work mainly depend on the 6 DOF force and torque applied by the user to the handle. The 6DOF sensor structure and its measurement principle are given in our work in detail. The whole system is consisted by signal amplifiers, control motors, integrated 6 DOF force sensor and power supplies needed for operation.

Virtual Space Teleconferencing System (VST), which based on video teleconferencing system, is a combination of Virtual Reality and several other techniques, such as Network Communication and Natural Language Processing. Participants appear in computer-generated virtual spaces as avatars in VST, and these avatars can locate, view, manipulate virtual objects, communicate with others face to face, so participants could share 'the same space' and do cooperative work. When participants use different kinds of natural language to communicate, language barrier would arise in interaction. So, besides the basic natural language processing, VST should provide translation service based on Machine Translation. First, this paper introduces the features of VST. Second, it describes the techniques of English-Chinese Bi-directional Machine Translation. Third, it analyzes the special requirements of English-Chinese bilingual interaction environment in VST. Finally it discusses the key issues of English-Chinese bilingual interaction environment and proposes a method of construction.

Electromagnetic tracking devices are often used to track location and orientation of a user's hand and/or head in a Virtual Reality system. However the tracking precision is not always high enough due to the dependence of the system on the local electromagnetic field that can be easily altered by ambient magnetic fields. A tracking system with pulsed AC (Alternative Current) magnetic field is presented based on the analysis of the principle and shortcomings of the DC (Direct Current) electromagnetic tracking system. The structure of the proposed system and the iterative digital correlator used for processing the received data are described. The simulation result shows the feasibility of the proposed system. Actual electromagnetic tracking system can be designed on the basis of the research.

In this paper, we present a new framework NAVER for virtual reality application. The NAVER is based on a cluster of low-cost personal computers. The goal of NAVER is to provide flexible, extensible, scalable and re-configurable framework for the virtual environments defined as the integration of 3D virtual space and external modules. External modules are various input or output devices and applications on the remote hosts. From the view of system, personal computers are divided into three servers according to its specific functions: Render Server, Device Server and Control Server. While Device Server contains external modules requiring event-based communication for the integration, Control Server contains external modules requiring synchronous communication every frame. And, the Render Server consists of 5 managers: Scenario Manager, Event Manager, Command Manager, Interaction Manager and Sync Manager. These managers support the declaration and operation of virtual environment and the integration with external modules on remote servers.

The concept and origin of distributed virtual simulation system are introduced. The usability, applicability and the method of realization of the application of DVR in SCADA simulation system are discussed here. A practical distributed virtual simulation system of civil airport refueling SCADA system is introduced in the paper.

The Workshop of Metasynthetic Engineering is a human-computer system for analyzing the strategy and method of collectivity layout and implement of complex huge system. Virtual conferencing space (VCS) can provide the seamless virtual collaboration work environment including eye contacts and gaze awareness, which matches the need of user-level application environment of Workshop of Metasynthetic Engineering. Based on virtual conference space, we implement a collaborative environment, which supports group cooperation and integration seminar. In this paper, we introduce the conception of virtual conferencing space, discuss the model and implementation of VCS, and then introduce the solution of how to support CSCW in VCS-based Workshop of Metasynthetic Engineering.

A cooperative shared haptic virtual environment, where the users can kinesthetically interact and simultaneously feel each other, is beneficial for many VR simulations. A little is known about the influences of the network delay on the quality of haptic and the performance in such environments. This paper has addressed this issue by exploring the haptic sensation and the performance in a tele-handshake cooperative shared haptic system, where network emulator was exploited to simulate the real network cloud. An experiment for different delay settings has been conducted and an objective and subjective evaluation has been described. An objective evaluation of the force feedback and the performance showed that there was no noticeable effect of the delay on the force feedback, but it had a negative impact on the performance. Meanwhile, the subjective evaluation suggested that the quality of haptic sensation deteriorated as the delay increased. Nevertheless, the examined tele-handshake system was able to deliver a high quality of haptic sensation, good performance, and stability for large delays.

The article presents the fruits of the study on distributed integrated environment of virtual reality application in our country, and DVENET, the first distributed integrated environment of virtual reality application based on computer WAN in our contry, which is mainly composed of the environment system and a series of development tools. By the environment system and development tools, we can rapidly establish applied virtual reality system, and master the study method on virtual reality. The article also points out a series of essential theory problems to be solved. Any break-through in these problems will enhance the progress in VR technology, distributed virtual environment and practical degree. It is a study field full of energy and challenges.

This paper introduces the main functions and technologies used in distributed full-mission marine simulator developed by Dalian Maritime University recently. As a facility for research analysis, captain training, engineering design, the simulation system has advantages of high accuracy mathematical model, low price and can display three dimension scene with 270 degree viewing field, ship dynamic image on ECDIS (Electronic Chart Display Information System) and radar image of certain sea area for training. The paper describes the main technologies used in the simulator include DIS (Distributed Interactive Simulation) technology, ship manoeuvring mathematical model, ship dynamic display based on ECDIS, Radar image, 3D scene generation using OpenGL and OpenGVS and network technology etc. The paper also introduces the application of this system in wharf design, pilot plan etc.

Funded by the Singapore National Science and Technology Board (NSTB), CAMTech is collaborating with a Singaporean research institute and two industry partners with the objective to improve electronics assembly processes. The goal of this project is to visualize the behavior of an electronics assembly industry by simulating, visualizing the discrete events of the entire manufacturing processes and observing the flow of materials, size of buffers, and line balancing. The traditional scenario -- from the customer placing order for a product to delivery -- goes through various phases including manufacturing the product. Several major electronics manufacturing stages can be addressed: fabrication, assembly, testing, and packing. Each of these stages accounts for set up, process, failure, and wait time periods. A delay in one process will accumulate over to the future delays. To simulate the discrete events a general-purpose simulation system has been employed. For modeling and visualization CASUS (Computer Animation of Simulation Traces) system has been used developed by Fraunhofer Institute for Computer Graphics (Fraunhofer-IGD). This work focuses on the prototype interface between simulation trace file and CASUS animation scripts. The final system provides a 3-D visualization of electronics assembly processes based on event-oriented simulator data.

Applications of Virtual Reality (VR) technology in many fields have gained great success. In the product development field, VR is a good tool to provide interactive and friendly human-machine interface. Freeform Object Design and Simultaneous Manufacturing (FODSM) uses VR to establish an interactive design environment and enable simultaneous manufacturing. It aims at improving design efficiency, creativity, ease of use, and also aims at integrating design and manufacturing in order to obtain the designed object by the designer independently and simultaneously. For the current stage, key technologies to implement FODSM include the algorithm of swept volume calculation and the following Boolean operation, mechanism to provide natural and intuitive feedback. This paper uses an analytical and experimental method to implement the novel design and manufacturing technology. Key issues are analyzed and tested. Experimental details are demonstrated.

The absence of efficient constraint management facilities when interacting with virtual objects is one of the major limitations of current virtual reality (VR) systems for CAD applications. Without constraint management facilities, it is difficult to perform precise interactions with today's 3D input devices and precise solid modeling in the VR environments cannot be ensured. In this paper, a constraint manager is presented for intuitive and precise solid modeling in the VR environment. This constraint manager generates constraint-based 3D direct manipulations for precise solid modeling through incorporating constraints into the VR environment. Constraint-based manipulations are realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix for conveniently deriving allowable motions from constraints. A procedure-based degree-of-freedom incorporation solver for solving 3D constraints is presented for deriving the allowable motions. A rule-based constraint recognition engine is developed for implicitly incorporating constraints into the VR environment.

A technical principle about construction of virtual studio has been proposed where orientation tracker and telemeter has been used for improving conventional BETACAM pickup camera and connecting with the software module of the host. A model of virtual camera named Camera & Post-camera Coupling Pair has been put forward, which is different from the common model in computer graphics and has been bound to real BETACAM pickup camera for shooting. The formula has been educed to compute the foreground frame buffer image and the background frame buffer image of the virtual scene whose boundary is based on the depth information of target point of the real BETACAM pickup camera's projective ray. The effect of real-time consistency has been achieved between the video image sequences of the master of ceremonies or players and the CG video image sequences for the virtual scene in spatial position, perspective relationship and image object masking. The experimental result has shown that the technological scheme of construction of virtual studio submitted in this paper is feasible and more applicative and more effective than the existing technology to establish a virtual studio based on color-key and image synthesis with background using non-linear video editing technique.

With the application of virtual reality in assembly, a completely new training means can be now used in the equipment maintenance training. The key techniques of virtual assembly system for equipment maintenance training (VASEMT) are introduced from four aspect in this paper. They are the virtual equipment modeling, the vstereo display of virtual environment, the human-computer interaction based on the data glove and 3-D spatial compound collision detection.

Contemporary demands on ceramic sanitary products tend more and more to emphasize diversification and individuation. How to provide effective techniques to support interactive design and presentation of ceramic sanitary products has become a great challenge for vendors. This paper presents a general framework for ceramic sanitary products design. Some dynamic adjustment algorithms of curves to support surface parameterized modeling of toilet bowl, which is one of the most complex ceramic products, are proposed. Furthermore, the VR-based display and customization environment is also illustrated. With the VRML and Java, our system not only offers users different products, but also allows users to reset selected bathroom scene through replacing products from modeling database and modifying attributes of different products, such as colors, positions, etc. Then a brief discussion and future research directions are put forward in the last part of this paper.

Today's product design, especially the consuming product design, focuses more and more on individuation, originality, and the time to market. One way to meet these challenges is using the interactive and creationary product design methods and rapid prototyping/rapid tooling. This paper presents a novel Freeform Object Design and Simultaneous Manufacturing (FODSM) method that combines the natural interaction feature in the design phase and simultaneous manufacturing feature in the prototyping phase. The natural interactive three-dimensional design environment is achieved by adopting virtual reality technology. The geometry of the designed object is defined through the process of "virtual sculpting" during which the designer can touch and visualize the designed object and can hear the virtual manufacturing environment noise. During the designing process, the computer records the sculpting trajectories and automatically translates them into NC codes so as to simultaneously machine the designed part. The paper introduced the principle, implementation process, and key techniques of the new method, and compared it with other popular rapid prototyping methods.

An appropriate oriented assembly product model should not only contain comprehensive and integral definition of each individual part but more importantly should also contain the definition of all the assembly relations between subassemblies and parts. First, the configuration information is collected and recorded in a configure file and attribute of relevant designed part solid models during stamping die tools design process. On the basis of configure file and CAD solid models, an assembly graph summarized the assembly relations inside of assembly is built. A stamping die tools product model is composed of all component part solid models, a configure file and an assembly graph. Afterwards, intelligent partition rules of subassemblies are presented. As a result of the partition, a whole assembly of stamping die tools is divided into several subassemblies and individual parts, and a hierarchical assembly tree is generated corresponding based on assembly graph. Assembly sequence planning can be generated by reasoning on the basis of configure file, asembly graph and hierarchical asembly tree. At last, an example is used to present the approach of assembly sequence planning and the simulating process of automatic assembling of stamping die tools.

On the basis of the technologies of virtual assembly and virtual prototype, this paper mainly discusses the method of product tolerance analysis, aiming at its present condition and existent problems. It introduces the technology's connotation, extension and application examples, and explains its application perspective.

Recently we have built the largest Virtual Reality (VR) theatre in the world of the Kyongju World Culture EXPO 2000. Unlike single user VR systems, the VR theatre is characterized by a single shared screen and controlled by several hundreds of people in the audience. The large computer-generated stereo images displayed by the huge cylindrical screen provide the feeling of immersion into 3D virtual environment that is augmented by the physical theatre space. In addition to the visual immersion, the theatre provides 3D audio, vibration and olfactory display as well as keypads for each and everyone in the audience in their seats interactively control the virtual environment. This paper introduces the issues raised and addressed during the design of making the VR theatre, production process and presentation techniques using the versatile display and interaction capabilities of the theatre.

This paper presents a new framework of an immersive kendo game with an intelligent cyber-fighter, which has its own internal needs, motivations, sets of multimodal sensors, a motor system, and a behavior system. Unlike conventional interface such as keyboard or joystick, the proposed system provides more natural and comfortable interface by exploiting multimodal interfaces such as 3D vision and speech recognition. In addition, the proposed 3D vision-based interface allows relatively free-movement in 3D space, when it compares with wired tracker-based interfaces. As a result, the user with real sword can experience an immersive fighting with the cyber-fighter in virtual environment. The proposed framework will have wide variety of applications in VR-based edutainment applications.

This article describes a training and information system being developed within the framework of a project for the Heinz Nixdorf MuseumsForum, the well known computer museum. The project in question involves the development of an interactive multimedia VR/AR exhibit. Visitors to this exhibit are provided with an eventful insight into the operation of a computer and the Internet. The exhibit consists of different modules covering various topic areas that visitors can work through in sequence. Depending on their respective interests, visitors can then find out more about the overall topic area. This article describes the individual modules (zones) and their subject matter. The project being described within this article is still in progress. The development phase is scheduled to be completed by the end of 2002, at which time the exhibit will be opened to visitors to the museum.

It is important to look for alternative forms of physical movement of people and equipment, to assure diagnosis and maintenance tasks. To reach this aim a lot of researches are being done in different fields of maintenance and computer science. An evident and classical solution is the use of the tele-operation and tele-robotics trough Internet. If the tele-operation helped to solve a lot of real and technical problems, it still remains insufficient to assure an appropriate remote diagnosis and maintenance. The use of virtual reality techniques with the tele-operation can be the solution for an effective remote maintenance and diagnosis. In this paper we show the inefficiency occurred with the only use of tele-operation in the remote maintenance, we introduce our system, explain its structure, implementation and its advantages.

This paper introduces the design of a reconfigurable driving simulator platform for a category of heavy ground vehicles while complying with the ISO 6682 specifications. Basically the steering wheel, pedal, and levers are designed using a linkage to be reconfigurable within a certain zone. Alternatively the platform can be thought of as having a range of configurations such that one is able to put a seat, steering wheel, gas pedal, or levers anywhere within a zone defined by ISO 6682. This platform is intended to be the first such design while fulfilling most of the requirements deemed important at this stage. The design is modular an flexible and can be enhanced in future as more data is collected through studies in actually usng the platform in a VR environment.

Virtual imaging technology is being used to augment television broadcasts -- virtual objects are seamlessly inserted into the video stream to appear as real entities to TV audiences. Virtual advertisements, the main application of this technology, are providing opportunities to improve the commercial value of television programming while enhancing the contents and the entertainment aspect of these programs. State-of-the-art technologies, such as image recognition, motion tracking and chroma keying, are central to a virtual imaging system. This paper reviews the general framework, the key techniques, and the sports broadcasting applications of virtual imaging technology.

This paper describes a computerized simulation system for minimally invasive vascular interventions using Virtual-Reality (VR) based technology. A virtual human patient is constructed using the Visible Human Data (VHD). A knowledge-based human vascular network is developed to describe human vascular anatomy with diseased lesions for different interventional applications. A potential field method is applied to model the interaction between the blood vessels and vascular catheterization devices. A haptic interface is integrated with the computer simulation system to provide tactile sensations to the user during the simulated catheterization procedures. The system can be used for physician training and for pre-treatment planning of interventional vascular procedures.

In this paper we describe a virtual bowling game machine called EasyBowling Machine, which is designed and implemented based on techniques such as Virtual Reality, animation, and image processing. To introduce Virtual Reality technique into this virtual bowling game, our system provides a real game mode: players play the game by throwing a real bowling ball, and then the EasyBowling system uses a PC Camera to detect the motion of the real bowling ball. After the motion parameters (ball direction, ball force, et al.) are computed, the movement of the bowling ball and its collision with pins are simulated on a large display screen. The most obvious advantage of such bowling game machine over other existing bowling games is that the system integrates body exercise into game playing. The implementation techniques are discussed in detail, and the prototype system illustrates the feasibility and efficiency of our method.

The object of this research is to decide which system is more effective between a VR system and a video system in military training. The performance of VR system used in experiment was evaluated through some questionnaire. Then a VR system and a video system is compared with drawing a rough map which presents effectiveness on mission area training. Correlation between sketched map and some questionnaire was calculated to find complementary factors improving the performance of the system.

This article describes a development environment in which 3D multimedia productions can be implemented effectively. Multimedia-enriched 3D environments, which can be used intuitively, are becoming increasingly widely used. The museum environment provides a typical example of this. The content for these applications is taken mostly from the areas of natural sciences and technology or history. In other areas, such as the production of complex, highly variant products, 3D multimedia information systems are required to support workers on the assembly line. These systems often have to be used universally because similar products are being developed at different sites. The best way, therefore, to feed content to such systems is online from a central server so that the information at all sites is similarly up to date. These information systems have still not broken through into the commercial sector, however. One of the reasons for this is that the proper development environments are not available for such online-based multimedia-enriched 3D information systems, which support the creation of these systems from the requirement analysis to startup. The information systems available to date are single systems, developed specifically for their respective application scenarios. The development environment described here aims to make that step from single-item production to custom-tailored series production. A consortium of industrial and university partners will begin to create this development environment and test it in a practical environment from early 2002, with planned completion within two years.

We present in this paper a new 3D interactive method for visualizing multimedia data with virtual reality. We consider that a domain expert has collected a set of examples described with numeric and symbolic attributes but also with sounds, images, videos or web sites, and that this expert wishes to explore those data in order to understand their structure. We use a 3D stereoscopic display in order to let the expert easily visualize and perceive the numerical attributes. We add to this display the appearing of contextual information such as texts, voice synthesis, sound, small images. Larger images, videos and web sites are displayed on a second computer in order to ensure real time display. Navigating through the data is done in a very intuitive and precise way with a 3D sensor with six degrees of freedom that simulates a virtual camera. Interactive request can be formulated by the expert with a data glove that recognize the gestures. We show how this tool has been applied to a real world application in the context of human skin analysis.

Virtual realistic highway networks consist of many road segments that are subject to link constraints between them. These constraints ensure the road segments to link together seamlessly and smoothly. This leads to the geometric data of the highway networks reliable for driving simulation. A difficult task in computer generation of such realistic 3D highway networks is linking the road segments by trial and error. In this paper we present a 3D modeler that allows semi-automatic generation of realistic highway scene based upon parameterized modeling technology. Here "semi-automatic generation" means that a user can interactively create or modify any individual road segment and other scene component, and then the modeler automatically links or adjusts the road segments to satisfy the link constraints. We have developed a prototype of the modeler with Java3D. The modeler enables a user to quickly generate a highway scene for immersive simulation of driving of automobiles. The semi-automatic generation of highway networks facilitates design creativity and is more reliable and faster than putting together of road segments via trial and error.

Most of the current popular GIS software only has solved the connection between the static data and map data in landscape planning and evaluation, but they seldom concern that the time plays a very important role in the landscape planning and evaluation system. In this paper, according to the multi-hierarchical dynamic property existing in the landscape planning and evaluation system, a concept of dynamic interaction is introduced, a kind of three-dimensional dynamic GIS model for landscape planning and evaluation system (it is named 4D-GIS-Model) is proposed, methods for the realization of the system based on this model are discussed, and a simple application of this dynamic GIS model is given finally.

In order to study the constructing technology of virtual shop-floor environment, the structure model of virtual shop-floor environment was first presented in this paper, and the object-orient technique was used to establish its basic classes and relevant models, including solid model, behavior model and object-oriented Petri net (OPN) based control model, and based on this, the constructing of whole virtual shop-floor environment was realized. The application proved that the virtual shop-floor environment had many good characteristics, such as interaction, visualization, multi-layer, open and reusability, and was an efficient tool for analyzing and modeling the layout planning and rapidly reconfiguring of shop-floor.

Color image quantization is a strategy in which a smaller number of colors are used to represent the image. The objective is to make the quality approximate as closely to the original true-color image. The technology is widely used in non-true-color displays and in color printers that cannot reproduce a large number of different colors. However, the main problem the quantization of color image has to face is how to use less colors to show the color image. Therefore, it is very important to choose one suitable palette for an index color image. In this paper, we shall propose a new approach which employs the concept of Multi-Dimensional Directory (MDD) together with the one cycle LBG algorithm to create a high-quality index color image. Compared with the approaches such as VQ, ISQ, and Photoshop v.5, our approach can not only acquire high quality image but also shorten the operation time.

In this paper, the application of the Virtual Reality Modeling Language (VRML) for efficient database visualization is analyzed. With the help of JAVA programming, three examples of automatic visualization from a database containing 3-D Geometry are given. The first example is used to create basic geometries. The second example is used to create cylinders with a defined start point and end point. The third example is used to processs data from an old copper mine complex in Cheshire, United Kingdom. Interactive 3-D visualization of all geometric data in an online database is achieved with JSP technology.

Vector field occurs not only extensively in scientific applications but also in treasured art such as sculptures and paintings. Artist depicts our natural environment stressing valued directional feature besides color and shape information. Line integral convolution (LIC), developed for imaging vector field in scientific visualization, has potential of producing directional image. In this paper we present several techniques of exploring LIC techniques to generate impressionistic images forming artistic virtual environment. We take advantage of directional information given by a photograph, and incorporate many investigations to the work including non-photorealistic shading technique and statistical detail control. In particular, the non-photorealistic shading technique blends cool and warm colors into the photograph to imitate artists painting convention. Besides, we adopt statistical technique controlling integral length according to image variance to preserve details. Furthermore, we also propose method for generating a series of mip-maps, which revealing constant strokes under multi-resolution viewing and achieving frame coherence in an interactive walkthrough system. The experimental results show merits of emulating satisfyingly and computing efficiently, as a consequence, relying on the proposed technique successfully fabricates a wide category of non-photorealistic rendering (NPR) application such as interactive virtual environment with artistic perception.

In this paper we propose a novel 2D plenoptic function called "acentric panorama view (APV)." This novel 2D plenoptic function has the feature that it samples the panorama scenes without oversampling and undersampling like the traditional panorama view. A single APV can be accelerated by view culling and list-priority rendering algorithm. Constructing multiple APVs concentrically, we can have a novel 3D plenoptic function (concentric APVs), which is similar to conetric mosaics and can highly enhance the visibility around the center. The concentric mosaics is indeed a subset of our concentric APVs.