GPU-assisted ray casting of large scenes

We implemented a pipelined rendering system that pre-renders a reduced set of a scene using the raster method built in the graphics hardware. The computation performed by the graphics card is used as an estimate for evaluating the initial traversal points for a ray caster running on the CPU. This procedure replaces the use of complex spatial subdivision structures for primary rays, offloading work that would traditionally be executed by the CPU and leaving additional system memory available for loading extra scene data. The ray traversal algorithm skips even narrow empty spaces, which are usually hard to map using conventional spatial subdivision. We achieved interactive frame rates (3-10 frames/s) running the system on a single computer with conventional hardware.