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Blender 2.70: Motion Tracker

Weighted Tracks

Tracking WeightedMarker-1.png

Weighted tracks were implemented (r60948)

A very common problem when performing a camera or object track is when a trackable feature in a video clip suddenly is unavailable. This happens when the tracked feature moves out of frame or behind something that blocks the camera's view. This problem is worsened when there are few available features to track, and the feature that is leaving the frame or being blocked from view, is closer to the camera than the other tracking markers. The sudden decrease of perspective information causes the solver to calculate erratic jumps in the camera motion. This type of error can look bad or could even ruin your entire shot.

Now each tracking marker can be assigned a weight which determines the influence it has on the overall solution. The weight of a tracking marker can be edited by it's weight slider located in the Track Panel, in the properties sidebar. These weight influences also can be animated. Now a tracking marker can, for example, "fade out" of use over a range of any number of frames. Altering the weights of problem tracking markers can correct or greatly reduce undesirable jumps.

Another use of Track Weigths is when you want to reconstruct a scene from your camera solution. In that case you can first carefully track and solve your scene, and once you're done, lock all your markers with Ctrl+L, set the tracker weight in the Extra Settings of the tracker settings to 0 and use the feature detection to quickly add lots of markers. Now track them and solve the scene again. Since their weight is 0 they will not influence your solution at all, but you will have lots of good reference points in your scene. Here is a video to demonstrate it:


Plane Track

Blender2.70-PlaneTrackImage.png

A couple of improvements were done for plane track. Now plane track gives real perspective warping and an image can be assigned to a plane track within the Movie Clip Editor. The image can be displayed during editing in the Movie Clip Editor to give real-time feedback about how the final composite frame will look.

Here is a quick tutorial from Sebastian Koenig about plane track image.

Harris Detector

Blender was using the FAST library for feature detection. It worked fast (as the name suggests) but features that the FAST library detected weren't very robust.

Now a new detector is has been put into effect which is called by it's author's name: Harris. The Harris Detector works a little slower and will detect fewer features than the FAST library, but the quality of the features is expected to be higher.

Smaller changes

  • Added support of displaying per-frame reprojection error of tracks in curve view of the Movie Clip Editor.