Rendering transparent objects with caustics using real-time ray tracing

Abstract

After the release of the NVIDIA RTX platform, ray tracing methods are available in real-time rendering and improves the render quality. Therefore, realistic results can be produced in real time by combining ray tracing with rasterization techniques. However, rendering transparent objects with roughness and caustics in real time is still a challenge. We focus on these points and propose a model to render transparent objects based on real-time ray tracing. The model consists of two parts: Iterative Ray Tracing Transparency (IRTT) and Light Half Path Caustics (LHPC). IRTT approximates accurate reflections and refractions by tracing rays, computes volumetric absorption using the length that a ray propagates inside a transparent object, and simulates the rough transparency by bending the normal vector. Meanwhile, LHPC approximates caustics with a method named Local Light Tracing (LLT), where the main task is finding the point of incidence by tracing rays in the direction of the light source. After, a denoiser assisted by a distribution method is applied to suppress the noise. In the experiments, we design a combined pipeline and compare it with our model in terms of performance and render quality. In addition, our results are also compared with rasterization techniques. The experimental results reveal that our model improves the quality of the rendered image and offers a playable framerate.