Optimal Combination of Disparity arcoss a log Polar Scaled Visual Field

Abstract

The human visual system is foveated and the spatial resolution of processing decreases with eccentricity. Sensitivity to stereoscopic disparity varies with spatial frequency and is band-pass tuned in the central visual field. Here, we assess the contributions of different regions of the visual field to disparity processing at different spatial scales. Observers were shown pink noise stereograms, which contained tilted (45° or 135°) sinusoidal corrugations at different modulation spatial frequencies. The corrugation filled a central 21° circular region, or was confined to annular regions spanning 0°-3°, 3°-9° or 9°-21°. Observers indicated the orientation of the corrugation. As expected, disparity sensitivity was band-pass tuned for spatial frequency and the peak shifted to lower spatial frequencies in the peripheral visual field. The envelope of disparity sensitivity for the full field stimulus was the optimal combination of sensitivities across the annular regions. We employed these data to tune and evaluate a foveated log-polar model of disparity processing that mimics the processing stages occurring in primary visual cortex. The model is based on a similar approach we previously developed for the processing of optic flow information directly in the cortical domain [Chessa et al, 2016]. We thus provide a map of disparity sensitivity throughout the visual field and across spatial frequencies, and a biologically plausible model that provides evidence for which neural processing stages are responsible for the topography of disparity sensitivity in man. The common computations of optic flow and stereo disparity in a log polar architecture could be combined to investigate the neural basis of the perception of motion in depth.

Meeting abstract presented at VSS 2017