Development of a virtual reality toolkit on the internet by a ASP.NET/Java']JavaScript approach

The main objective of this paper is to develop an integrated Microsoft ASPNET/JavaScript prototype for interactively building up virtual environments from existing geographical information system (GIS) databases that include Landsat images, spatial vector data and digital elevation map (DEM. This prototype takes advantage of both the ASPNET and JavaScript approaches, providing a flexible and user friendly interface, which making better use of the power of the server. It is also beneficial to balancing of workloads on both client and server sides. The prototype, called Geographical Virtual Reality (GVR), has been implemented by utilizing JavaScript on its client side and correspondingly, on its server side by the C# language. The GVR server is responsible for generating 3D scenes according to parameter values sent from the JavaScript client. The 3D scenes are then transformed to VRML models, and delivered to the Internet browser for display and navigation. This toolkit, allowing common users to interact with 2D GIS data on the Internet and create perspective views from these data dynamically, demonstrates how to extend an existing web GIS into a more powerful virtual GIS. It can also be used in the subsequent applications.