Dev:Ref/Release Notes/2.68/Motion Tracker

Blender 2.68: Motion Tracker

Reconstructed scene scale ambiguity

Improved algorithms which deals with reconstructed scene scale ambiguity (r56632).

This is done by scaling reconstructed scene in a way so reconstructed cameras variance is unity with a median in the 3D scene origin.

Such approach helps in cases when different keyframe pair gives the same exact reconstruction from math point of view but some of which could be considered bad by artists because of bad scale.

Scene Orientation

• Added a button to apply scale on scene solution (r56635).

This is an alternative to using camera to scale the scene and it's expected to be better :solution because scaling camera leads to issues with z-buffer.

• Apply scale on scene reconstruction when applying scale on camera (r56764)

This means when you've got reconstructed scene assigned to a 3D camera (via camera solver constraint) and applies scale on this camera from Ctrl-A menu, scale will be applied on the reconstructed scene and reset camera size to identity.

This is very useful feature for scene orientation, when you'll just scale camera by S in the viewport to match bundles some points in the space, and then you'll easily make camera have identity scale (which is needed for nice working motion blur without loosing scale of bundles themselves.

Behavior of apply scale for cameras without clip assigned to them does not change at all.

Refine Markers Position

Added Refine Markers Position operator (r56716).

This operator will run a tracker from previous keyframe to current frame for all selected markers. Current markers positions are considering initial position guess which could be updated by a tracker for better match.

Useful in cases when feature disappears from the frame and then appears again. Usage in this case is the following:

• When feature point re-appeared on frame, manually place marker on it.
• Use Refine Markers operation (which is in Track panel) to allow tracker to find a better match.

Depending on direction of tracking use either Forwards or Backwards refining. It's easy: if tracking happens forwards, use Refine Frowards, otherwise use Refine Backwards.

Automatic Keyframe Selection

Added an option to select keyframes used for initial reconstruction automatically (r57133).

This option enables some fancy math algorithms which tries to find a keyframe pair with minimal reconstruction error and best scene scale guess.

Smaller improvements

• Made bundles in 3D viewport have constant size (they're not affected by camera scale anymore) (r56633)
• Set scene frames operator for clip editor (r56664). This operator will set scene's start/end frames to match clip's start frame and footage duration.
• Marker placement for motion tracker by clicking on a desired location (r57138).
• Track Position node now could output absolute position of track at a given frame (r57414)