For replacing backgrounds or tracking out of focus regions, Mocha’s Unlink Workflow is an incredibly powerful technique to learn. In this useful video tutorial, Mary Poplin shows how to track a handheld camera move and replace the background sky with Mocha’s planar motion tracking in Adobe After Effects.
Keying was done with Continuum’s Primatte Studio plugin.
Unlink creates an offset relationship between the layer’s search area (the spline) and the surface (the track). Create a layer, then in Layer Properties, select Link to Track: None. When you track, notice the search area will not move and you now have an offset relationship between the Spline and Surface.
This example is shown running the Mocha Pro plug-in inside Adobe After Effects, but the unlink technique can be used in any version if Mocha plug-in or standalone application.
Find more great Mocha tracking tips at Mocha TV