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Interpreting Figure of Merit


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In this example, two trackers have been supervised-tracked with a Key Every setting of 20 frames (but starting at different frames). The tracker Figure of Merit (FOM) curve measures the amount of difference between the tracker’s reference pattern and what is found in the image. You see it drop down to zero each time there is a key, because then the reference and image are the same.

One tracker has a small FOM value that stays mostly constant. The other tracker has a much larger FOM, and in part of the shot it is much larger. In a supervised shot, the reason for that should be investigated.

You can use this curve to help decide how often to place a key automatically. The 20 frame value shown above is plenty for those features. If you see the following, you should reduce the spacing between keys.


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You’ll also be able to see the effect of the Key Smooth setting: the key smoothing will flatten out a steadily increasing curve into a gently rounded hump, which will reduce spikes in the final camera path.

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