 |
 |
I agree with Alasdair. My observations so far: - If one wants to query a 3D scene(view) visible from a fixed viewpoint then its much better to use z-buffer type approaches. Its much faster and sufficient to compute distances to nearest visible parts. I believe this is already incorporated in GIS software e.g. ArcView's 3D analyst, which uses an OpenGL viewer window. - There is a need to discuss what a 3D-VGA most useful for. A straightforward extension of 2D- VGA applications would not always make sense. I would like to differ though on the relevance of 3D space to people behaviour. I think its relevant to characterise the 3D view from a location because whats standing (and hanging in the air), would also effect how people use/perceive the space. For example, my experience of Tokyo and New York is made up of mostly three-dimensional memories/images that includes sky scrapers, high neon billboards, bridges etc. - On a more practial note, one application that could potentially benefit from 3D VGA is that of CCTV installation. Sanjay.