Disparity (spelling variant - disparity ) (from lat. Disparatus - divided) - the difference in the relative position of the points displayed on the retina of the left and right eye . Image disparity lies at the basis of the unconscious psychophysiological processes of binocular and stereoscopic vision .
Content
The physiological mechanism for the use of disparity
It has been shown by neurophysiology methods that binocular neurons of the primary visual cortex begin to decode disparity.
The mathematical model of disparity
Disparity is characterized by the difference between the horizontal and vertical angular coordinates of the image of a point on the retinas of two eyes .
The figure shows the surface defined by points A 1 , A 2 , A 3 that are at the same distance from the observer. The point of view of the observer is directed at point A 2 (fixation point), therefore it is projected into the fovea (central fossa) of the retina of his eyes (points O l , O r ). The surfaces of the left and right retinas are connected with the coordinate systems O l X L , O r X R in such a way that the center fovea is at point 0. Let the region of negative coordinate values ββlie to the left of the points O l and O r . The projections of the point A 1 have coordinates x 1l and x 1r on the left and right retinas, respectively, and the projections of the point A 3 have coordinates x 3l and x 3r . The coordinates of the projections of the points located at the same distance from the observer as the fixation point on both retinas coincide, that is, x 1l = x 1r , x 3l = x 3r . It is said that these points in space are projected onto the corresponding (corresponding) points of the retina.
Consider the point A 4 located closer than the fixation point. The projection coordinates of such a point are related by the inequality x 4l <x 4r (since x 4l <0, x 4r <0). For point A 5 (not shown in the figure) located further than the fixation point, the inequality x 5l > x 5r holds . These points of the world around are projected onto the non-corresponding or disparate points of the retina or, what is the same, they show disparity. Convergent (at points located closer to the fixation point) and divergence (at points located further than the fixation point) are distinguished. The distribution of disparity over an image is sometimes called a disparity map .
See also
- Parallax
Literature
- Woodworth R.S. Visual Perception of Depth / R. C. Woodworth // Psychology of Sensations and Perceptions. - M .: CheRo, 1999 .-- S.343-382.
- Marr D. Vision. Information approach to the study of the representation and processing of visual images / D. Marr; Per. from English N. G. Gurevich. - M.: βRadio and Communicationsβ, 1987.- 400s.
- Rozhkov S. N., Ovsyannikova N. A. Stereoscopy in film, photo, video equipment. Terminological dictionary. - M.: Paradise, 2003 .-- 136p.
- Shulgovsky V.V. Fundamentals of Neurophysiology: Textbook M .: Aspect Press, 2002