An adaptive distributed ray tracing with automatic differentiation

Ray tracing is well known as one of the most popular rendering techniques in computer graphics. In the algorithm tracing rays from a viewpoint and calculation of intersection between rays and objects are essential. Since the rays are usually defined as piecewise lines precisely, they can not include the neighbor situation even if the neighbor is very close. Therefore the rays must be distributed, i.e., additional rays must be defined along with the original ones in order to obtain the neighbor situation. In this paper we introduce the so-called automatic differentiation to detection whether the rays are to be distributed or not. In the proposed method each calculation of the ray tracing has its differentiation with respect to coordinates and time. Then we can discover where the rays need distribution. This approach makes the distribution adaptive so that the computational cost becomes low