The perception of 3D shape from texture

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Our eyes present to us a world in three dimensions, and yet the information coming in through the eyes is not three dimensional. The retina that sits at the back of each eyeball is effectively a two-dimensional sheet of receptor cells. The light that is reflected or emitted from three-dimensional objects in the world is actually transduced as two-dimensional patterns on the retina. So how do we perceive the third dimension of depth on the basis of these two-dimensional patterns? This is a classic question in the area of visual perception, and many decades of research have resulted in a list of depth cues that our visual systems use to "reconstruct" the third dimension. What we are still trying to understand is, precisely how does the visual system utilize each cue to perform this feat of perception?With support of the National Science Foundation, Dr. Todd will closely examine the nature of one visual depth cue called "optical texture". To illustrate, imagine looking closely at a dimpled golf ball. The visual appearance of the dimples is warped by the curvature of the ball, and our visual systems can use this warping as a source of information about its roundness in all three dimensions. Dr. Todd has developed a computational model of how the visual system calculates the shape of an object based on its textural patterning, and the present research project will investigate whether his model is an accurate characterization of how the human visual system uses optical texture as a depth cue. Experiments will be conducted to precisely test how human participants use optical texture, and the results from these experiments will be compared against the predictions of the model. Besides advancing our knowledge of human visual perception, these results may inform the design of more robust and effective algorithms in machine vision and computer graphics, and more functional prosthetic devices for the blind.