On enhancing the speed of splatting using both object- and image-space coherence

Splatting is an object-order volume rendering algorithm that produces image s of high quality, and for which several optimization techniques have been proposed. This paper presents new techniques that accelerate splatting algo rithms by exploiting both object-space and image-space coherence. In partic ular, we propose two visibility test methods suitable for octree-based spla tting. The first method, based on dynamic image-space range trees, offers a n accurate occlusion test and does not trade off image quality. The second method, based on image-space quadtrees, uses an approximate occlusion test that is faster than the first algorithm. Although the approximate visibilit y test may produce visual artifacts in rendering, the introduced error is u sually not found very often. Tests with several datasets of useful sizes an d complexities showed considerable speedups with respect to the splatting a lgorithm enhanced with octree only. Considering that they are very easy to implement, and need little additional memory, our techniques will be used a s very effective splatting methods. (C) 2000 Academic Press.