Fast raycasting using a compound deep image for VPL range determination

The concept of using multiple deep images has been explored, under a variety of different names, as a possible acceleration approach for finding ray-geometry intersections. We leverage recent advances in deep image processing from Order Independent Transparency (OIT) for fast building of a Compound Deep Image (CDI) using a coherent memory format well suited for raycasting. We explore the use of a CDI and raycasting for the problem of determining distance between Virtual Point Lights (VPLs) and geometry for indirect lighting, with the raycasting step being a small fraction of total frametime.