Camera Tracker: Troubleshooting

This topic describes some common problems you might encounter when using the Camera Tracker, and gives suggestions about how to fix them.

Feature Tracking Halts Immediately

If the feature tracker attempts to match the first couple of frames but halts immediately, check these steps:

  1. One of the enabled error thresholds might be set too low. Perform a Check Status in the Batch Track rollout and look at the reports in the Tracking Error Review list. Also try disabling the thresholds in the Error Thresholds rollout one at a time and see if this fixes the problem. Adjust the problematic threshold as needed. You can also disable error threshold checking altogether by turning off the Resample On Error check box in each of the trackers.
  2. Make sure the search bounds box for each tracker is big enough to accommodate the frame-to-frame motion of the feature. This needs to be at least big enough to enclose the moved feature and the surrounding contrast area you’ve selected in the feature bounds box.
  3. Make sure the scene objects are associated correctly with their trackers. You can verify this by checking the entries in the list at the top of the Motion Trackers rollout. If there is an object associated, you will see its name in the list entry, if not you will see “<no object>”. If you open a movie file for which you have previously set up trackers in the camera tracker before you open the associated 3ds Max scene, the objects won’t be associated with their trackers. You should make sure the correct 3ds Max scene is open then close and reopen the movie file in the Camera Tracker so that it can now find the scene objects.
  4. If you have inadvertently swapped the scene objects for one or more pairs of trackers, the match-move can’t find a solution.

Repeated Match-Move Errors

If you get repeated camera match-move errors, here’s a list of things to check:

  1. Make sure there are at least six features actively being tracked at the error frame and that at least two of them are a good distance out the plane of the others.
  2. Check the tracker gizmos in the Movie window around the frame on which the error occurs to ensure that no obvious feature tracking errors exist.
  3. If you’ve disabled any parameters in the Match section of the Match-Move rollout prior to a match-move, the camera being matched must be already set correctly in the scene for those parameters. For example, if you disable roll and FOV, you must already have set the camera to the correct FOV and roll orientation, either directly in 3ds Max, or as a result of a previous match-move. The matching algorithm uses all the “fixed” camera parameters to compute the ones being estimated and simply won’t work if they’re fixed at incorrect values.
  4. You may know that some of the camera parameters don’t vary during a match sequence, but you aren’t sure of their values. One approach to this situation is to enable all parameters for an initial match and then apply a straight-line average filter to them in the Move Smoothing rollout. This automatically disables them in the Match section and with luck sets them at a good estimate of the fixed position.