Stable Sample Caching for Interactive Stereoscopic Ray Tracing

We present an algorithm for interactive stereoscopic ray tracing that decouples visibility from shading and enables caching of radiance results for temporally stable and stereoscopically consistent rendering. With an outset in interactive stable ray tracing, we build a screen space cache that carries surface samples from frame to frame via forward reprojection. Using a visibility heuristic, we adaptively trace the samples and achieve high performance with little temporal artefacts. Our method also serves as a shading cache, which enables temporal reuse and filtering of shading results in virtual reality (VR). We demonstrate good antialiasing and temporal coherence when filtering geometric edges. We compare our sample-based radiance caching that operates in screen space with temporal antialiasing (TAA) and a hash-based shading cache that operates in a voxel representation of world space. In addition, we show how to extend the shading cache into a radiance cache. Finally, we use the per-sample radiance values to improve stereo vision by employing stereo blending with improved estimates of the blending parameter between the two views.