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The Cyclopean View

One of the most amazing properties of human stereo vision is the fusion of the left and right views of a scene into a single cyclopean one. Under normal viewing conditions, the world appears as seen from a virtual eye placed midway between the left and right eye positions. The perceived image of the world is never recorded directly by any sensory array, but constructed by our neural hardware.

Consider the following stereo view:

 - left and right Pic of a roboter grip -

If you close either the left or the right eye, you will notice how the perspective switches between left and right view, and a perspective located somehow between these two: the cyclopean image.

Because left and right retinal images are not identical (that's why we can calculate the depth of a scene in the first place), a simple superposition of the two images would lead to diplopia for most parts of the image:

left and right pic overlayed

Note how the gripper and the small wooden block appear with double contours.

Proper fusion requires the alignment of the two monocular views to some common image coordinate system. This can be done only if the disparities for the image parts to be fused are known.

In coherence-based stereo, the cyclopean view of the scene is created as a simple side-product of the disparity calculations, within a single network structure. The scene appears in this cyclopean image as it would have been seen from a virtual eye, placed midway between the two real eye positions:

calculated cyclopean perspective

Again, the cyclopean image displayed above is a constructed view, and was never taken by any camera.

As a matter of fact, it is even possible to create all virtual views between the two real eye-positions. A small movie showing a simulated camera-movement from right to left and back, constructed only from the two stereo-pictures, can be seen here:

Gif-Movie of virtual camera
Stereo image was supplied by by the Kiel Cognitive Systems Group, G. Sommer, Christian-Albrechts-University of Kiel.

Comments are welcome! © 1997 by Rolf Henkel - all rights reserved.