Title	3D Reconstruction of Piscine Vision
Detail	In Biology, it is always interesting to study the relationship between the behaviour of an animal, in this case a fish, and its sensory system. By observing the animal's reaction under various circumstances, the biologist can understand more about the animal's nervous system and how it co-ordinates the other systems in the animal's body. One problem in this study is to calculate and visualise the visual acuity volume of the fish. This is a very suitable problem to be solved by applying some techniques from volume visualisation in the computer graphics field. We investigate some well-known methods in volume visualisation, studying both surface fitting (SF) algorithms and Direct Volume Rendering (DVR) algorithms. We find that Marching Cubes and Ray Casting methods are suitable algorithms for solving our problem. We choose the Common Smelt as the object of study in the experiment. Its visual acuity volume is determined by its eyeball structure, or more precisely the mosaic of photoreceptors on the retina and the magnifying factor of the lens. The adult Smelt has a different photoreceptor density distribution on the retina than a young Smelt. It also behaves in a different way under outside stimuli. The data set we get from the Biologists consists of mainly two parts: a series of photographs of frozen slices of Smelt head and two photoreceptor density maps of a Smelt left retina, one for an adult, one for a young Smelt. We use the photos of frozen slices to determine the geometric parameters of the fish visual system, such as size and orientation of the eyeball, location of the lens within the eyeball and the spatial relation between the two eyeballs. We use the photoreceptor density map to determine the visual acuity scalar field outside the fish body. We draw iso-surfaces to visualise this scalar field. The results obtained with our method confirm the behaviour of the Smelt as observed by the Biologists. On one hand, the differences in the photoreceptor densities on the retina determine the differences in the visual acuity in different directions of the visual field. These differences subsequently determine the difference in the behaviour. On the other hand, different photoreceptor density distributions on the retina of the adult and the young Smelt give them a different perception of the outside environment, and they will therefore react in different ways.
Authors:	Former member: Parker Shao
Year	2000
URL	http://www.cs.auckland.ac.nz/GG/parker_shaw.html

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