Photometric stereo with uncalibrated lights determines surface orientations ambiguously up to any regular transformation. If the surface reflectance model is separable with respect to the illumination and viewing directions, its inherent symmetries enable to design two previously unrecognized constraints on normals that reduce this ambiguity. The two constraints represent projections of normals onto planes perpendicular to the viewing and illumination directions, respectively. We identify the classes of transformations that leave each constraint invariant. We construct the constraints using polarization measurement under the assumption of separable reflectance model for smooth dielectrics. We verify that applying the first constraint together with the integrability constraint results in bas-relief ambiguity, while application of the second constraint on integrable normals reduces the ambiguity to convex/concave ambiguity. Importantly, the latter result is also obtained when the first and second constraints alone are combined.
Unambiguous determination of shape from photometric stereo with unknown light sources
Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001 ; 1 ; 581-586 vol.1
2001-01-01
595410 byte
Conference paper
Electronic Resource
English
Unambigous Determination of Shape from Photometric Stereo with Unknown Light Sources
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