Global structure of visual space as a united entity

Abstract

Visual space (VS) is the final product of the series of processes, physical, physiological, and perceptual. Two planes in VS are discussed. Though each can be regarded as Riemannian space of constant Gaussian curvature K, a plane passing through the eyes that extends in the depth direction is hyperbolic (K<0) whereas a plane appearing fronto-parallel is Euclidean (K=0). Empirical and mathematical bases for this structure of VS are presented. How VS is related to the stimulus condition is complex and dynamic, but the intrinsic structure of VS per se is homogeneous in the sense that we can see global congruence and/or similarity between figures, provided the corresponding physical objects are appropriately adjusted. All percepts appear at finite distances and VS is closed. Perceptual structure of natural scene, e.g. appearance of the horizon, is discussed.