Technical Report No. 21, April 1990 - Abstract

Bernd Lamparter, Heinrich Müller, Jörg Winckler:
The Ray-z-Buffer - An Approach for Ray Tracing Arbitrarily Large Scenes

The ray-y-buffer algorithm presented here is part of an alternative strategy of ray tracing called breadth first ray tracing. Breadth first ray tracing differs from usual pixelwise rendering in tracing whole generations of rays together. This means that first all rays of view are treated, next the set of reflecting and refracting rays, then the reflecting and refracting rays caused by them, ans so on. The calculation of intersections for a generation of rays uses the ray-z-buffer algorithm. Like the z-buffer algorithm the ray-z-buffer algorithms allows to render scences with an unbounded number of primitives. An implementation based on nested adaptive quadtrees is presented. Analysis and measuring show the rendering time increasing sublinearly in the resolution of the image, and increasing linearly in the number of primitives. The main memory required only depends on the resolution of the image, in about linear manner.