Quantifying the optical and rendering pipeline contributions to spatial resolution in augmented reality displays

Abstract

The measured spatial resolution of augmented reality head-mounted displays (AR HMDs) is determined by three components: optics, display, and the rendering pipeline, which includes the anti-aliasing method. Therefore, separating and quantifying the contributions from these components is necessary for evaluating the spatial resolution of AR HMDs. We demonstrate a method for quantifying the contributions from the optical performance and the rendering pipeline on the spatial resolution of AR HMD using point-spread function (PSF) analysis. In this method, an imaging photometer captures a series of rendered scenes on the AR HMD that consist of arrays of spheres of increasing sizes with different anti-aliasing (AA) methods. The contributions from the optics, display, and anti-aliasing methods can be separated, and we find that temporal anti-aliasing (TAA) and multisample anti-aliasing (MSAA) are in good agreement with the performance of no AA. However, fast approximate anti-aliasing (FXAA) results in decreased luminance for smaller rendered targets and a different spatial resolution for larger targets. Finally, we repeated our methods on multiple HMDs and characterized the dependence of the spatial resolution across the field of view. These measurements show significant non-uniformity in the optical contribution to the spatial resolution.