Caustic Illuminance Calculation with DirectX Raytracing

The possibility of implementing physically correct rendering of scenes with caustic illuminance using the DirectX Raytracing API with its subsequent integration into the real-time rendering pipeline is studied. The proposed method is based on the use of additional visibility maps for forward caustic illuminance and visibility maps for backward caustics, which are created for light sources and a virtual camera, respectively. The paper considers the possibility of using backward photon mapping by means of the DirectX Raytracing API and presents an algorithm for calculating the caustic illuminance and the results of testing the software implementation of the proposed algorithm with various method parameters. The dependence of the rendering speed on the scene parameters and characteristics that determine the quality of the caustic luminance calculation—the number of rays emitted by the light source, the maximum depth of the specular ray path, and the number of light sources in the scene is studied. The test results showed that the developed algorithm and its software implementation can provide high-quality calculation of caustic illuminance in real-time and can be used in the gaming industry to increase the realism of visual perception when rendering scenes with complex lighting conditions.