Tracking over many frames
	So far we’ve only considered two frames Basic extension to f frames 1. Select features in first frame 2. Given feature in frame i, compute position/deformation in i+1 3. Select more features if needed 4. i = i + 1 5. If i < f, go to step 2
	Issues • Discrete search vs. Lucas Kanade? – depends on expected magnitude of motion – discrete search is more flexible • How often to update feature template? – update often enough to compensate for distortion – updating too often causes drift • How big should search window be? – too small:  lost features.  Too large:  slow