Interactive 3-D spatial analysis in a virtual reality environment

Doctoral Thesis


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University of Cape Town

The emergence of virtual reality and related tools enables the fundamental infrastructure to begin building virtual cities, which can provide an interactive simulation and analysis environment for planning and management of urban places. The virtual city will provide urban managers with a computer environment to interface with the multitude of complex physical and social data needed to plan and manage cities. A range of innovative technologies are being developed that offer different ways of modelling and representing built-form and associated urban information with real-time interaction over the Internet. For all these efforts in technological development, one of the main topical issues remains, the development of a representation (data structure) that is capable of both static and dynamic spatial analysis operations. This research focuses on developing a 3-D data representation for urban management, which would fully support both static and dynamic spatial analysis operations. It further explores the possibilities inherent in a hybrid of the Boundary representation (B-rep) and distance field modelling (a technique which is finding application in 3-D medical imaging). The research makes an analysis of the existing B-reps before developing the best form which could easily be integrated with the Distance Field (DF). Since this is the first known research in application of DFs in urban GIS, the research further offers the design and adoption of Distance field maps. Further designs are undertaken for the necessary algorithms that would allow dynamic analysis operations to be implemented within the DF environment. The conceptual design is mapped through Entity-Relationship modelling into a Database Management System (DBMS). The B-rep component is maintained within the DBMS whilst the DF component is generated on the ""fly"". For the distributed application development, a 3-tier approach that merges the client-side (web browser), application server and database server is proposed. Based on this approach, a Web based prototype toolkit is designed and implemented using affordable ""off-the-shelf' software applications and resources that are relatively easy to set-up and use, and would require standard PC-processor power available to a home user with a modem link (i.e. not a high-end graphics workstation). The novel aspects of this thesis can be summarised as: 1. The use of a hybrid representation is new in 3-D GISs. 2. The use of Distance Fields and the development of related spatial analysis operations is new in Geo-Information Systems. Furthermore, the research proposes a new distance field modelling approach; the single Distance Fields (see Chapter 5). 3. The implementation environment makes use of the existing tools and integrates them in a novel way.

Includes bibliographical references.