Stereo Vision: Examples of how the Cross-Correlation Model extracts the disparities

 IS-P: I made this animated GIF to demonstrate how the cross-correlation model works (Banks et al. 2004, The Journal of Neuroscience). 
       The example is a random-dot estereogram showing a Horizontal sinusoidal corrugation of 0.2 c/deg with a disparity of 5 arcmin. 
       Top image is an anaglyph version (for correct view, place the red filter in front of the right eye). 

 

 

 

In this example, the spatial sensors (2D gaussians with std=12 arcmin) move vertically.

In this example, the spatial sensors (2D gaussians with std=12 arcmin) move horizontally.

Examples of Convolution and Correlation operations

 IS-P: I made these examples using Matlab to show the differences between convolution (Left panels) and correlation (Right panels) operations.

 

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 IS-P: These examples show the Convolution operation using a Difference of Gaussians kernel for a rectangular wave (Left panel) 
       and a profile of the Mach bands (Right panel) (after Békésy, 1960, Neural inhibitory units of the eye and skin: 
       Quantitative description of contrast phenomena. JOSA, 50).

    

Aperture problem

 IS-P: I made this animated gif to show and example of the Barber's Pole illusion and the Aperture problem

Definitions of Relative and Absolute disparities.

IS-P: I just made these images to explain the definitions of absolute and relative disparities.

 

 

 

IS-P: Calculus of binocular disparity of a 3D dot using the anaglyph technique.

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Missing fundamental motion illusion

 IS-P: I made these examples in order to show this interesting motion illusion

Examples

 

Squarewave signal moving rightward.		Missing fundamental. Squarewave signal moving rightward without the fundamental or first harmonic. Do you see it moving rightward?

 

                    

Analysis of the stimuli

 

 

Example of the missing fundamental illusion. Top left panel, spatio-temporal plot (x-t plot) of a squarewave stimuli (0.5 c/deg) moving rightward. Top right panel, x-t plot of the squarewave with the first harmonic removed (i.e. missing fundamental). Note that the edges are moving rightward but the stimulus is perceived moving leftward. Bottom panels show the spatio-temporal amplitude spectrum of the top x-t plots. Bottom-left panel, the energy of the first harmonic is located in the quadrants 1 & 3 (moving rightward). Bottom-right panel, spatio-temporal spectrum of the missing fundamental. Note that although the edges in the x-t plot are moving rightward, however, the energy of the current first harmonic (1.5 c/deg) is located in the quadrants 2 & 4 (moving leftward). By Ignacio Serrano-Pedraza.