Examination of the Nvidia RTX

Abstract

Hardware acceleration of ray tracing is an active research field, but only with the release of Nvidia Turing architecture GPUs it became widely available. Nvidia RTX is a proprietary hardware ray tracing acceleration technology available in Vulkan and DirectX APIs as well as through Nvidia OptiX. Since the implementation details are unknown to the public, there are a lot of questions about what it actually does under the hood. To find answers to these questions, we implemented classic path tracing algorithm using RTX via both DirectX and Vulkan and conducted several experiments with it to investigate the inner workings of this technology. We tested actual hardware implementation of RTX technology on RTX2070 GPU and the software fallback in the driver on GTX1070 GPU. In this paper we present results of these experiments and speculate on the internal architecture of RTX.