Use of hardware Z-buffered rasterization to accelerate ray tracing

Abstract

Ray tracing is a rendering technique for producing realistic 3D computer graphics. Compared to traditional scan-line rendering which is generally adopted by graphics pipeline, ray tracing can simulate more realistic global illumination, however, with the cost of expensive computation. In this paper, we implement a ray tracer that combines advantages of both rendering schemes: efficiency of scan-line rendering and reality of ray tracing. We first use hardware-accelerated rasterization with Z-buffer to quickly determine the first ray-triangle hit of eye rays on the GPU. Secondary rays such as reflective and shadow rays are then traced to generate global illumination on the CPU with a bounding volume hierarchy (BVH) which plays the role of our acceleration structure. The experiments show that rasterization is much more efficient in finding the first hit and can completely replace the traditional ray casting procedure.