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Virtual Reality (VR) systems are today being successfully employed for real-time visualization in such diverse fields as chemistry, medicine, simulation, construction, design, and architecture. Comparatively few, however, are being used for the interactive spatial display of large geographical datasets; such systems are neither generic nor portable, and are often only implementable on expensive high-end graphics workstations. Database-backed Geographical Information Systems (GISs) provide a multitude of possibilities for the manipulation of geographical data, without providing the real-time access to multi-dimensional data required by VR systems. The interactive visualization of large geographical data volumes does not rely, as do most GISs, on a two-dimensional presentation, but rather on three-dimensional visualization technology. Interactive display of spatial data requires an optimized computer graphics architecture. Common workplace computers have dramatically increased in power, offering today what would have been considered super-computer calculation power ten years ago. Optimized graphics subsystems are available for all common business Personal Computers (PCs), and offer a much better price-performance ratio than graphics super-workstations. Through hardware implementation of graphics routines, the display of three-dimensional datasets can be significantly accelerated. Computer Science has also made enormous progress. Through the use of object-oriented programming paradigms, problems can be specified on a very high, abstract level. This simplifies the implementation of portable, hardware-independent applications. Through the use of sophisticated object-oriented programming frameworks, "Rapid Application Prototyping" has become a key concept in modern software development. Complex applications can be easily assembled using special "visual" editors, with the underlying framework then filling in the necessary code. Highly sophisticated object-oriented frameworks, geared to the demands of VR visualization, provide the user with the possibility of creating virtual worlds with very little programming effort. This dissertation will show, through the implementation of physical models and advanced algorithms, that it is feasible to deploy an economically viable Virtual Reality system for the interactive visualization of large geographical datasets. The coupling of a VR system with an object-oriented database for the administration of large geographical data volumes offers both efficient memory and data retrieval management as well as interactive visualization. The implementation of two concrete applications and the concept of code reuse will show that the effort required for the development of VR systems is not significantly increased. The use of a VR framework allows the software engineer to provide a skeleton program possessing all the required components of a VR-based geographical information system. The terms Virtual Reality and Geographical Information Systems, and their integration into a Virtual Reality based Geographical Information System, are discussed in chapter 1. In chapter 2, the architecture of an existing VR system for visualizing large geographical datasets is taken as the foundation for further development with WordView. The foundations of software engineering for Virtual Reality applications are discussed in chapter 3. Chapter 4 is concerned with the necessary hardware requirements for such systems. Chapter 5 covers the use of standard software packages for implementing Virtual Reality systems. Aspects of system architecture, development, and implementation with the WorldView Virtual Reality framework are discussed in chapter 6. Chapter 7 covers applications based on WorldView used for antenna placement optimization and building visualization. Price/performance measurements are a central element of real-time applications and are covered in chapter 8 with reference to a WorldView prototype application. Final comments and ideas for future research activities are discussed in chapter 9.

WorldView - Ein generisches Virtual Reality Framework für ...

WorldView - Ein generisches Virtual Reality Framework für die interaktive Visualisierung grosser geographischer Datenmengen

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