GLOBAL MODELS AND THE W3DS SPECIFICATION - CHALLENGES AND SOLUTIONS
Gunnar Misund, Markus Granlund, H. Kol · 2005
The recently proposed Web 3D Service (W3DS) specification defines how to access and retrieve geospatial 3D scenes integrating terrain data, textures and local content such as buildings and city furniture. In this paper we discuss some of the issues arising when using W3DS to access huge models, potentially of the entire globe, where high resolution content is embedded. We claim that the only sound approach to deploying such models is to generate the content on demand, based on the requested geographic area and other parameters. Examples are presented, including constructing 3D buildings on-the-fly from the original 2D/2.5D sources, along with empirical results, indicating that this is a feasible strategy. We also show that efficient content caching may reduce response times significantly. Based on lessons learned, we propose a minor extension of the W3DS specification in order to assure seamless navigation in global models assembled from distributed, autonomous data sources. The most crucial components of the proposed strategies are implemented and tested on a real life model. 1