Mocha Pro Product Manager at Imagineer Systems, Martin Brennand provides a great look at how and why you would actually use the Attache Layer Tool in Mocha Pro and in Mocha for After Effects V3.
Product Manager Martin Brennand takes you through a quick example of how to use the Attach Layers tool in mocha v3
Martin creates a pretty good example where typically in rotoscoping you try not to make your roto shapes too large as that will be unwieldy with tons of keyframes for too many points.
Larger shapes will be difficult to gain control of smoothly from frame to frame and instead, by making smaller shapes and tracking them for the lower moving jaw in two or more layers, will make it is easier to control the tracking for an area where the motion is less consistent over a larger area.
By using the attach tool, you are able to attach two or more tracked shapes so they will actually keep their original track, but tightly butt up against each other leaving no gaps between the layers.
