November 8, 2010

Reverse stabilization and 'Roto Assist'

Chris Zwar shared some resources on first stabilizing shots with camera movement, then doing keys or roto in a thread on the AE-List on the Roto Brush tool ("roto assist" when it bogs down) .

For more on the Roto Brush see AE Help (stabilization) and AEP posts with Roto Brush or stabilization resources. In addition to this advice, there's more from Chris on Thoughts on keying - The Myth of the Single-Click:

"Roto Brush will disappoint anyone who HASN'T had to do meticulous frame-by-frame rotoscope work before, and therefore doesn't know how tedious and difficult roto can be. Having a tool that gets you 70% of the way there is still a valuable time saver. But I haven't yet had a shot where it worked perfectly by itself. [snip]

In the same way that keying can be improved by pre-prossessing the footage to remove grain and adjust hue/saturation, images can also be pre-processed to improve rotoscoping too, and to help the roto brush plugin.

When I'm doing roto on any scene with camera movement I use a 3-step inverse camera process- firstly I motion stabilise the shot, then I work on the stabilised shot, then I put the original camera movement back in. I call it 'inverse camera' but it's also called 'reverse stabilisation' and it's demonstrated in a much more interesting way by Andrew Kramer:

It's also demonstrated on the Creative Cow:

And the technique is then elaborated on by Roland:

If I'm working with people who are new to rotoscoping then I get them to watch Andrew's tutorial first, because working on stabilised footage can make the roto process so much easier."

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