Photometric stereo with gradated extended sources for recovery of specular surfaces.
A photometric stereo technique is proposed that uses four extended sources and specular reflection to estimate surface topography. It is shown that if the intensity of incident light is weighted according to its zenith angle, then the radiance of surface facets will vary linearly with their slope. A simple system that approximates this lighting distribution is demonstrated. It is shown that surface slope in the range [-0.5, 0.5] can be recovered to within a multiplicative constant.
McGunnigle
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Carinthian Tech Research AG, CTR AG, Europastrasse 4/1, 9524 Villach, Austria. gerald.mcgunnigle@ctr.at