Exploiting Space and Time Coherence in Grid-Based Sorting

In recent years, many approaches for real-time simulation of physical phenomena using particles have been proposed. Many of these use 3D grids for representing spatial distributions and employ a collision detection technique where particles must be sorted with respect to the cells they occupy. In this paper we propose several techniques that make it possible to explore spatio-temporal coherence in order to reduce the work needed to produce a correct ordering and thus accelerate the collision detection phase of the simulation. Sequential and GPU-based implementations are discussed, and experimental results are presented. Although devised with particle-based simulations in mind, the proposed techniques have a broader scope, requiring only some means of establishing subsequences of the input which did not change from one frame to the next.