837eb6bb18
The last tracker commit added normalized tracking. This makes tracking patches undergoing uniform illumination change easier. However, the prepass which computes a quick translation-only estimate of the warp did not take this into account. This commit fixes that. This works reasonably well but in some examples the brute initialization fails. I suspect this is due to the warped template estimate in the current frame being too different from the original, so there are multiple peaks in the normalized-SAD correlation function. The solution is to use the previous frame for the brute initialization and the keyframe for refinement, but that requires architecture changes.