Proximity clouds - an acceleration technique for 3D grid traversal

In this paper we present a new method for the acceleration of ray traversal through a regular 3D grid. A distance transformation is precomputed and mapped onto the empty grid space. A ray traversing the empty space is assisted by the distance values which permit it to perform long skips along the ray direction. We show that the City-Block metric simplifies the preprocessing with no penalty at the traversal phase. Different schemes are discussed and the trade-off between the preprocessing time and the speed-up is analyzed.