Posts Tagged long-range

Linked-flow for long range correspondences

This last week, I thought I could use linked optic flow to obtain long range correspondences for part of my project. In fact, this simple method of linking pairwise flow works pretty well. The idea is to compute pairwise optic flow and link the tracks over time. Tracks that have too much forward-backward error (the method is similar to what is used in this paper, “Object segmentation by long term analysis of point trajectories”, Brox and Malik).

I didn’t end up using it for anything, but I wanted to at least put it up the web. In my implementation I used a grid to initialize the tracks and only kept tracks that had pairwise frame motion greater than a threshold, that were backward forward consistent (up to a threshold), and that were consistent for enough frames (increasing this threshold gives less tracks). New tracks can be added at any frame when there are no tracks close enough. The nice thing about this is that tracks can be added in texture-less region. In the end, the results are similar to what you would expect from the “Particle Video” method.

Here are a few screenshots on two scenes (rigid and non-rigid).room_tracks

arm_tracks

But it is better to look at the video:

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