Correcting Grid Deformation

No matter how sophisticated tracking becomes, some sequences are inevitably going to cause problems. If your grids drift or deform, you can adjust the grid points manually and then ripple the relative adjustments to other frames in the sequence.

For example, tracking backwards from the grid's origin in this sequence results in deformation around the actor's eye as his head rotates.

1.

Enable ripple above the Viewer and then manually correct the grid points, creating a keyframe at the beginning of the sequence.

2.

Set the ripple type to range and then enter the frame range between your correction and the point in the sequence where the grid is correct.

3.

Correct the grid using the points in the Viewer.

Play through the sequence to the grid origin and check that the relative transforms are applied correctly.

You can also use the Track Rigidity control above the Viewer to confine the grids to straighter lines, allowing less deformation. Lower values allow the grid to follow the tracking data more freely, whereas higher values force the grid to retain its original shape.

Note:  You must set the Track Rigidity value before tracking. Adjusting rigidity after tracking has no effect.

In the example, the grid has deformed as the actor's head rotates. This is not necessarily bad tracking, but for more angular shapes you can increase the Track Rigidity to confine the grid to more regular shapes.

Low Track Rigidity.	High Track Rigidity.

Proceed to Warping Shots with GridWarpTracker when your grids are stable and accurate.