Discussion of Output

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‌Bad tracker color . RGB color values. These are the 0-255 RGB values for the color any bad trackers are set to. If you empty this field, the tracker colors will not be changed. See also View/Tracker Appearance/Use alternate colors.

Fundamentally, the Find Erratic Tracker tool's only necessary output is the selected (bad) trackers. However, it also does produce a textual output that can assist in understanding and refining the input parameters. Here's an output and discussion:

14 bad trackers out of 600: 2.3%. Pretty self-explanatory, can be confirmed by the selection dropdown at top left of the main SynthEyes window.

Required 15 trackers in common between frames. This is how many frames are required to be able to determine if anything is the matter with those trackers, and is a result of both the Kernel Size and Kernel Count values.

Average travel 444.6 frames. Indicates how far apart, on average, it is able to look at pairs of frames, before the number in common drops below the required trackers in common value. This is a function of the lifetime of the trackers in your shot. If the shot is long but has too few trackers, this average travel will be short, and the tool will not be able to detect much. You might reduce the Kernel Size or Count, but it is probably better to rerun the autotracking, if you haven't done too much yet, with a much higher value for Minimum Trackers Per Frame on the Advanced tab of the Features panel.

1413/2960 bad kernels: 4.9%. Tells you how many of the kernels were too inconsistent to be usable, according to your Kernel Accuracy setting (and to a lesser extent, kernel size). The 5% value here is probably on the high side; it is better to keep it down towards 2-3% by increasing the Kernel Accuracy threshold. If there are few to none kernels, you may want to decrease the accuracy value, as you're probably not excluding some you should.

Histogram for adjusting 'Bad kernels%' (50% => 10) : The 50% is your current Bad kernels % setting; this is telling you that means 10 or more bad kernels of your kernel count of 20. The histogram is all the lines that follow.

Bad Histogram[1]: 69. There were 69 occasions where a tracker appeared in only one bad kernel.

Bad Histogram[2]: 18 18 occasions where it was in two bad kernels, etc.

Bad Histogram[10*]: 5. The asterisk(*) means that this number of bad kernels is over your bad kernels % setting, ie the tracker will be declared to be erratic. And etc.

Only non-zero values are shown. Note that the histogram does not necessarily add up to exactly your number of trackers.

The implication of the histogram is that if there are too many trackers that have been flagged, you should adjust the settings upwards, either the Tracker Accuracy or the Bad Kernel %. If there were too few, they can be adjusted downwards. Either way, you can then rerun the tool.

A proper histogram will have most counts at the beginning and end of the list, with a low area in between. Here you see a count of only one each on 7, 8, and 9. The threshold should be placed in or right above that low area. When a shot has too many issues to predict what where trackers should be, the histogram values will be largely constant or steadily decreasing, with no hole in the middle.

Keep in mind that this tool is statistical in nature. It will flag some trackers it shouldn't, and not flag some that it should. Nevertheless, it can very easily and rapidly identify trackers for further investigation.

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