Binocular perception of slant
| R. van Ee & C.J. Erkelens (1995). Binocular perception of slant about oblique axes relative to a visual frame of reference. Perception, 24, 299-314. |  |
In the presence of a visual reference divergence induces the same slant as does horizontal scale. Upper stereogram: the right half--image has a horizontal scale of -8% relative to the left half-image. Lower stereogram: the right image has a divergence of -8%. If vertical disparity is irrelevant for slant perception when a visual frame of reference is present, then this has major consequences for the classification of the elementary transformations that can be used to describe slant perception. This irrelevance suggests that divergence effectively induces the same slant as horizontal scale (as demonstrated in this figure). More specifically, we suggest that perceived slant relative to a visual frame of reference is related to a set of transformations of which only horizontal scale and horizontal shear are the basic orthogonal elements. Horizontal scale is associated with slant about the vertical axis of the stimulus. Horizontal shear is associated with slant about the horizontal axis.