Efficient Space Leaping for Raycasting Architectures

One of the most severe problems for ray casting architectures is the waste of computation cycles and I/O bandwidth, due to redundant sampling of empty space. While several techniques exist for software implementations to skip these empty regions, few are suitable for hardware implementation. The few which have been presented either require a tremendous amount of logic or are not feasible for high frequency designs (i.e. running at 100 MHz) where latency is the one of the biggest issues. In this paper, we present an efficient space leaping mechanism which requires only a small amount of SRAM (4 Kbit for a 256 volume) and can be easily integrated into ray casting architectures. For each sub-cube of the volume, a bit is stored in an occupancy map, which can be generated in real-time, using the VIZARD II architecture. Hence, space leaping can be classification dependent achieving yet another significant speed-up over skipping only the empty space (voxel = 0). Using a set of real-world datasets, we show that frame-rates well above 15 frames per second can be accomplished for the VIZARD II architecture.