Half Block Background Matching In Stereopsis Processing Mechanism

One of the fundamental problems faced by the visual system is that of reconstructing a three-dimensional representation of the world from two-dimensional retinal images. As first demonstrated by Wheatstone, combining information from two eyes is one of the most important ways of achieving this. One of the information sources for recovering depth is binocular disparity, which is the relative position difference between two binocular feather. Depth perception based on binocular disparity termed wheatstone stereopsis,or conventional stereopsis. Another information source of depth perception is the feather which is presented only in one view, called monocular feather. Depth perception based on monocular feather termed Da Vinci stereopsis. Da Vinci stereopsis is a demonstration of the half-occlusion relationship in real visual scene. When a near surface occludes a more distant surface, a portion of the far surface is visible to only one of the two eyes. This phenomenon is called half-occlusion. There are two major problems in those studies of half-occlusion. Firstly, it is hard to prove that monocular region alone can induce depth perception, because the stimuli in all the studies can not exclude matching cues completely, like the Da Vinci stereopsis demonstrations by Nakayama and Shimojo, and phantom stereopsis demonstrations by Gillam. Secondly, the depth location of monocular feather cannot be all calculated by conventional stereopsis, although it contains matching cues. That means either Da Vinci stereopsis or conventional stereopsis alone can not explain the two demonstrations of half-occlusion so well.In fact, a image contains figure and ground. It has never been taken into account that stereoscopic processing involve a background matching process. The depth perception of a binocular object can be exactly determined by binocular disparity in conventional stereopsis. But in half-occluded stereopsis, whether the processing of background can influence the whole stereoscopic vision is still not known, and has never been studied before. This is because that figure and ground was segregated so obviously that make us believed that figure was the part of this image get involved in detection of disparity, not ground. Besides, the background in demonstrations of Nakayama and Shimojo is a uniform illuminance, which is why we can not perceive the depth of background. That is why we should investigate the background processing in half-occlusion deeply. We adopted a new method, which is using RDS served as background of Da Vinci stimuli, to study the background processing in Da Vinci stereopsis. In 1965, The computer generated RDS unequivocally demonstrated that monocular form or contour perception was not a necessary antecedent to binocular matching and the generation of a depth map. That is exactly why we can use RDS to investigate the background processing in Da Vinci stereopsis that the depth location of RDS can be determined by disparity and it has no form perception.In our research we investigate the role of background matching process in Da Vinci stereopsis and the formation of phantom surface. The main content is as follows:1. Setting a new mode which can study the depth difference between binocular object and background in Da Vinci configuration. Based on this new mode, we investigate the background processing in half-occlusion2. conducting an experiment in which the random-dot stereogram was served as background. The result revealed that the depth perception of monocular region significantly reduced when the disparity between the paired object and the background was zero in paired stimuli. Our work suggests that Da Vinci stereopsis formation may involve a matching process of background.3. Based on previous conclusion, we deeply research the mechanism of phantom surface perception. By changing the color of monocular region to break the continuity of surface property, we observed if the phantom surface can still be perceived. We found that the phantom surface is not there anymore, which suggest that it was a necessary antecedent to formation of phantom surface that monocular regions and binocular surface should have the same property. The result imply that monocular region should be treated like background, not figure.