Abstract
Two dimensional (2D) images of light beams reflected off the objects in
space impinge on the retinal photoreceptors of our two laterally
separated eyes. Nevertheless, we experience our visual percept as a
single 3D entity—our visual world that we tend to identify with
physical world. However, experiments point to different geometries in
these two worlds. Using the binocular system with the asymmetric eyes
(AEs), this article studies the global geometric aspects of visual space
in the Riemannian geometry framework. The constant-depth curves in the
horizontal field of binocular fixations consist of families of arcs of
ellipses or hyperbolas depending on the AE parameters and the eyes’
fixation point. For a single set of AE’s parameters, there is a unique
symmetric fixation at the abathic distance such that the constant-depth
conics are straight frontal lines. Critically, the distribution of the
constant-depth lines is independent of such fixations. In these cases, a
two-parameter family of the Riemann metrics is proposed based on the
retinal topography and simulated constant-depth lines. The obtained
geodesics for a subset of metric parameters include the incomplete
geodesics that give finite distances to the horizon. The Gaussian
curvature of the phenomenal horizontal field is analyzed for all the
metric parameters. The sign of the curvature can be inferred from the
global behavior of the constant-depth ellipses and hyperbolas only when
for the metric parameters for which the constant-depth frontal lines at
the abathic distance fixations are geodesics.