Real-Time Ray Tracing With Polarization Parameters

Abstract: Background. The real-time renderers used in video games and similar graphics applications do not model the polarization aspect of light. Polarization parameters have previously been incorporated in some offline ray-traced renderers to simulate polarizing filters and various optical effects. As ray tracing is becoming more and more prevalent in real-time renderers, these polarization techniques could potentially be used to simulate polarization and its optical effects in real-time applications as well. Objectives. This thesis aims to determine if an existing polarization technique from offline renderers is, from a performance standpoint, viable to use in real-time ray-traced applications to simulate polarizing filters, or if further optimizations and simplifications would be needed. Methods. Three ray-traced renderers were implemented using the DirectX RayTracing API: one polarization-less Baseline version; one Polarization version using an existing polarization technique; and one optimized Hybrid version, which is a combination of the other two. Their performance was measured and compared in terms of frametimes and VRAM usage in three different scenes and with five different ray counts. Results. The Polarization renderer is ca. 30% slower than the Baseline in the two more complex scenes, and the Hybrid version is around 5–15% slower than the Baseline in all tested scenes. The VRAM usage of the Polarization version was higher than the Baseline one in the tests with higher ray counts, but only by negligible amounts. Conclusions.  The Hybrid version has the potential to be used in real-time applications where high frame rates are important, but not paramount (such as the commonly featured photo modes in video games). The performance impact of the Polarization renderer's implementation is greater, but it could potentially be used as well. Due to limitations in the measurement process and the scale of the test application, no conclusions could be made about the implementations' impact on VRAM usage.