Lext, JonasAkenine-Möller, Tomas2015-11-112015-11-1120011017-4656https://doi.org/10.2312/egs.20011018This article discusses methods for avoiding that the reconstruction of the acceleration data structure becomes a bottleneck in animated or interactive ray tracing. Situations in which this could occur include trying to increase the frame rate by parallelization of the ray tracing phase or by techniques such as frameless rendering. Specifically, we explore a method for avoiding unnecessary reconstruction in rigid-body animated scenes. The method builds a hierarchy of oriented bounding boxes containing recursive grids by applying these to the rigid bodies found in different transforms in the scene graph. The oriented bounding boxes containing gridded objects are then kept intact during the complete animation. Before performing intersection tests, rays are transformed to the local coordinate system of an oriented bounding box. Using this technique, the reconstruction of the data structure can be performed an order of magnitude faster as compared to using a recursive grid that has to be rebuilt completely between each frame.