The following is a preprint version of:
Evidence for surface-based processing of binocular disparity
Glennerster, A., McKee, S.P. and Birch, M.D.,
Current Biology, 12, 825-828 (2002)
preprint.pdf
preprint.ps.gz
Abstract
It is convenient to think of an object's location
as a point within a Cartesian framework; the x-axis corresponds
to right and left, the y-axis to up and down, and the
z-axis to forward or backward. When an observer is looking
straight ahead, binocular disparities provide information about
distance along the z-axis from the fixation plane (Koenderink,
1992; Howard and Rogers, 1995). In this coordinate system, changes in
disparity are treated as independent of changes in location along the
orthogonal x- and y-axes. Does the human visual system
use this three-dimensional coordinate system, or does it specify
feature location in a coordinate frame determined by other nearby
visible features? Here we show that the sensitivity of the human
stereo system is determined by the distance of points with respect to
a local reference plane, rather than by the distance along the
z-axis with respect to the fixation plane. There is a distinct
advantage to using a local frame of reference for specifying
location. It obviates the need to construct a complex
three-dimensional space in either eye-centered or head-centered
coordinates that must be updated with every shift of the eyes and
head.
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