Foveated Ray Tracing for VR Headsets.

In this work, we propose a real-time foveated ray tracing system, which mimics the non-uniform and sparse characteristic of the human retina to reduce spatial sampling. Fewer primary rays are traced in the peripheral regions of vision, while sampling frequency for the fovea region traced by the eye tracker is maximised. Our GPU-accelerated ray tracer uses a sampling mask to generate a non-uniformly distributed set of pixels. Then, the regular Cartesian image is reconstructed based on the GPU-accelerated triangulation method with the barycentric interpolation. The temporal anti-aliasing is applied to reduce the flickering artefacts. We perform a user study in which people evaluate the visibility of artefacts in the peripheral region of vision where sampling is reduced. This evaluation is conducted for a number of sampling masks that mimic the sensitivity to contrast in the human eyes but also test different sampling strategies. The sampling that follows the gaze-dependent contrast sensitivity function is reported to generate images of the best quality. We test the performance of the whole system on the VR headset. The achieved frame-rate is twice higher in comparison to the typical Cartesian sampling and cause only barely visible degradation of the image quality.