Year: 2017
Type: dissertation
Abstract: Depth perception is a major component of 3D vision. There are many cues to depth; one \nparticularly sensitive aspect is the vivid perception of depth created from having eyes with \noverlapping visual fields (binocular vision). As the eyes are located at different points in \nspace, they see different views of the scene – these slight differences (called binocular \ndisparity) can be used to obtain depth information. However, extracting depth from \ndisparity requires complex visual processing. So why use binocular vision? \n \nJulesz (1971) proposed an explanation – camouflaged animals can fool the perception of \nsome cues to 3D shape, but camouflage is ineffective against binocular vision. We would \nexpect that animals with binocular vision could see the 3D shape of animals, despite their \ncamouflage. Whilst commonly accepted, this hypothesis has not been tested in detail. In \nthis thesis, we present experiments designed to establish how depth from binocular vision \ninteracts with camouflage and object shape. Two main questions were addressed: \n \nFirst, we explored how the visual system represented depth information about 3D objects \nfrom binocular disparity. Objects with smooth depth edges (hill-shaped) were perceived \nwith less depth than sharper edged objects. A computational model that segregated the \nobject, then averaged the disparity over the segregated region emulated human \nperformance. Finally, we found that disparity and luminance cues interacted to alter \nperceived depth. \n \nSecondly, we investigated if binocular vision could overcome camouflage. We found that \ncamouflaged objects defined by luminance were detected faster when also defined by \ndepth from disparity, thus reduces the effect of camouflage. Smooth objects were detected \nslower than sharp objects: an effect that was replicated in the real world, suggesting a \ncamouflage technique to counter binocular vision. \n \nIn summary, binocular vision is useful because it can detect camouflaged objects. However, \nsmoother shapes take longer to spot, forming binocular (or stereoscopic) camouflage.
Author: Philip Cammack
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2977120046