Bias in Shape Estimation

TitleBias in Shape Estimation
Publication TypeBook Chapters
Year of Publication2004
AuthorsJi H, Fermüller C
EditorPajdla T, Matas J
Book TitleComputer Vision - ECCV 2004Computer Vision - ECCV 2004
Series TitleLecture Notes in Computer Science
Pagination405 - 416
PublisherSpringer Berlin / Heidelberg
ISBN Number978-3-540-21982-8

This paper analyses the uncertainty in the estimation of shape from motion and stereo. It is shown that there are computational limitations of a statistical nature that previously have not been recognized. Because there is noise in all the input parameters, we cannot avoid bias. The analysis rests on a new constraint which relates image lines and rotation to shape. Because the human visual system has to cope with bias as well, it makes errors. This explains the underestimation of slant found in computational and psychophysical experiments, and demonstrated here for an illusory display. We discuss properties of the best known estimators with regard to the problem, as well as possible avenues for visual systems to deal with the bias.