Michael Mara

Scalable ambient obscurance

This paper presents a set of architecture-aware performance and integration improvements for a recent screenspace ambient obscurance algorithm. These improvements collectively produce a 7 x performance increase at 2560 x1600, generalize the algorithm to both forward and deferred renderers, and eliminate the radius- and scene-dependence of the previous algorithm to provide a hard real-time guarantee of fixed execution time. The optimizations build on three strategies: pre-filter the depth buffer to maximize memory hierarchy efficiency; reduce total bandwidth by carefully reconstructing positions and normals at high precision from a depth buffer; and exploit low-level intra- and inter-thread techniques for parallel, floating-point architectures.

Toward practical real-time photon mapping: efficient GPU density estimation

We describe the design space for real-time photon density estimation, the key step of rendering global illumination (GI) via photon mapping. We then detail and analyze efficient GPU implementations of four best-of-breed algorithms. All produce reasonable results on NVIDIA GeForce 670 at 1920 × 1080 for complex scenes with multiple-bounce diffuse effects, caustics, and glossy reflection in real-time. Across the designs we conclude that tiled, deferred photon gathering in a compute shader gives the best combination of performance and quality.

Extended TimeWarp latency compensation for virtual reality

Head-mounted virtual reality displays exhibit latency between sensing the users head position and updating the camera transformation for the image on the screen. With current sensors, rendering pipelines, and displays, this latency is on the order of several milliseconds and is believed to contribute to simulator sickness symptoms of disorientation, headache, and nausea.[LaValle et al. 2014]