3D surface orientation based on a novel representation of the orientation disparity field

The orientation disparity field from two orthographic views of an inclined planar surface patch (covered by straight lines) is analyzed, and a new tool to extract the patch orientation is provided: the function coupling the average orientation of each pair of corresponding surface contours with their orientation disparity. This function allows identifying the tilt of the surface, and two indeterminacy functions describing the set of surface inclinations (around the vertical and horizontal axes) over convergence angle values compatible with the orientation disparity field. Results of simulations show that the selection of inclination values matching the difference between the areas below the indeterminacy functions are consistent with some surface orientation effects found in psychophysical and computational experiments, like: the unbiased tilt vs. biased slant estimates, the slant underestimation, the surface orientation anisotropy, and the slant/tilt covariation.