Perceptual Rasterization for Head-mounted Display Image Synthesis

TL;DR

This paper introduces a perceptual rasterization pipeline optimized for head-mounted displays, enabling low-latency, foveated, and rolling image synthesis in a single pass using per-fragment ray-casting, improving over traditional methods.

Contribution

It presents a novel perceptual rasterization method that combines foveation and low-latency image synthesis in one efficient pipeline using per-fragment ray-casting.

Findings

Effective foveated image rendering with spatially varying pixel density.

Reduced latency through direct rolling image generation.

Overcomes limitations of warping and geometric artifacts.

Abstract

We suggest a rasterization pipeline tailored towards the need of head-mounted displays (HMD), where latency and field-of-view requirements pose new challenges beyond those of traditional desktop displays. Instead of rendering and warping for low latency, or using multiple passes for foveation, we show how both can be produced directly in a single perceptual rasterization pass. We do this with per-fragment ray-casting. This is enabled by derivations of tight space-time-fovea pixel bounds, introducing just enough flexibility for requisite geometric tests, but retaining most of the the simplicity and efficiency of the traditional rasterizaton pipeline. To produce foveated images, we rasterize to an image with spatially varying pixel density. To reduce latency, we extend the image formation model to directly produce "rolling" images where the time at each pixel depends on its display location. Our approach overcomes limitations of warping with respect to disocclusions, object motion and view-dependent shading, as well as geometric aliasing artifacts in other foveated rendering techniques. A set of perceptual user studies demonstrates the efficacy of our approach.