# On Ullman's theorem in computer vision

@article{Knill2007OnUT, title={On Ullman's theorem in computer vision}, author={Oliver Knill and Jose Ramirez-Herran}, journal={ArXiv}, year={2007}, volume={abs/0708.2438} }

Both in the plane and in space, we invert the nonlinear Ullman transformation for 3 points and 3 orthographic cameras. While Ullman's theorem assures a unique reconstruction modulo a reflection for 3 cameras and 4 points, we find a locally unique reconstruction for 3 cameras and 3 points. Explicit reconstruction formulas allow to decide whether picture data of three cameras seeing three points can be realized as a point-camera configuration.

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