An acceleration technique using a 3D representation for ray tracers in a urban environment

An efficient algorithm for the selection of the surfaces visible from a source point has been proposed. If this method is applied to a ray tracer, it can produce a significant reduction of the computational time spent by the shadowing tests. The method is general and easy to implement even if the required memory might be large (at least 64 Mbytes). Further investigations will be carried out into problems related to image distortion in 3-D visualizations. In the future, this approach, now used to evaluate direct and reflected rays, will be extended to diffraction-related problems.