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Multi-view Stereo Beyond Lambert Jin et al., CVPR ’03 Joshua Stough November 12, 2003
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Basics Reconstruct 3D shape from calibrated set of views. (uncalibrated possible). Assume Non-Lambertian Establish Correspondence from model to image, NOT image to image Constraint on the radiance tensor field.
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Radiance Tensor Field Given point P on surface, g1,…,gn camera reference frames, and v1,…,vm vectors along tangent plane to P to tesselation around P. For Lambertian, rank is 1. For any “diffuse + specular” reflection model, rank 2. More specifically, any reasonably lit and viewed surface patch obeying the BRDF model has R(P) <= 2. Cost function can be matrix discrepancy between model R(P) and observed R(P).
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Discrepancy between their model and the observed drives a flow towards the correct shape. They prove that the Frobenius norm of the tensor discrepancy is optimizable. F norm: the obvious one (root of sum of squares of elements), as opposed to the square root of the max eigenvalue of the adjoint matrix (?). Key
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Kind of weird that they show that how nothing is practically like their model is a good thing (drives the optimization). Before, a weakness was this odd assumption that viewpoint doesn’t matter. Now assume opposite. Maybe use lambertian on badly matching patches for agglomerated surfaces? I don’t understand their geometry model. They say they don’t need points or triangles. How would they transmit results (like above)? Results
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