Generating signed distance fields on the GPU with ray maps

Abstract

Signed distance fields represent objects as distances to the closest surface points with a sign differentiating inside and outside. We present an algorithm to compute a signed distance field from triangle meshes. All data are kept on the GPU, making it ideal for any pure graphics-based context. We split the algorithm into a fast parallel distance transform and a new method of computing the sign. To determine the sign, we compute the winding number for any point using a ray map, a ray-based data structure that preserves geometric meaning while reducing the amount of work to be done for ray tests. Based on that structure, we devise a simple parallel algorithm to sample an exponentially growing number of rays to cope with meshes having deficiencies such as holes or self-intersections. We demonstrate how our method is both fast and able to handle imperfect meshes.