Direct methods for vision have widely used photometric least squares minimizations since the seminal 1981 work of Lucas & Kanade, and have leveraged normalized cross correlation since at least 1972. However, no work to our knowledge has successfully combined photometric least squares minimizations and normalized cross correlation: despite obvious complementary benefits of efficiency and accuracy on the one hand, and robustness to lighting changes on the other. This work shows that combining the two methods is not only possible, but also straightforward and efficient. The resulting minimization is shown to be superior to competing approaches, both in terms of convergence rate and computation time. Furthermore, a new, robust, sparse formulation is introduced to mitigate local intensity variations and partial occlusions.
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