Help! My mask won’t move!

[Steve Roberts]

The mask only interpolates its shape between keyframes set by you.

Now in AE, you can use *motion tracking* to track a point (or four), but those points can only be attached to the position of solids or effect points (say, the center of a lens flare). This does not help you, since you want to attach the trackers to mask vertices.

I believe that there may be expressions to work with mask vertices, which may or may not help you. Try searching the COW for “mask vertex” and “expression”.

But I think you want one of the tools by Imagineer systems like Mocha. But those cost money. (Note that the cheaper little Mocha for AE just tracks — it doesn’t actually mask. )

If you don’t have that, I’m afraid you’ll have to rotoscope the talent, which means setting mask shape keyframes by hand. It’s boring work, but you can avoid a lot of wasted time by studying the talent’s motion carefully, and only placing leyframes when the motion of his shape changes direction, say from left-moving to down-moving. Let AE interpolate between those points. And if something (like a head) doesn’t change shape, mask it separately then just move the entire mask into position when necessary.

No, it’s not automatic, but for that you gotta spend the bucks on a dedicated tool.

[Scriptshaker]

Hi Steve,

Thanks very much for the informative answer. I’d figured out as much right after I posted and just added enough keyframes to make the mask work, so I’m golden. But your solution info will come in very handy down the road. Thanks again.

E

[Steve Roberts]

Excellent.

Roto is an art, and it doesn’t have to be a total pain. The worst case would be an amorphous flowing blob, or a dancer wearing a big flowing cape. But a lot of things have shapes whose motion can be predicted and masked with minimal keyframes and vertices once we learn to study the motion and draw efficiently.