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Roto Brush Performance Issues & Seeking Advice.

May 14, 2013 7:51 PM

Hello everyone,

  First time posting in the forum, so I'll make this as painless as I can and hopefully I can get a hand in figuring this out.


Computer is a brand new Mac Book Pro 15in Retina Display.

- 2.7ghz Intel Core i7 (quad core)

- 16gb Ram


- NVidia GeForce GT 650m 1024 mb.

- OSX 10.8.3

- After Effects


The project that I'm working on right now was shot 1080, 24fps. I cut the project in Premier and copied all of the footage to AE for keying and to ad motion graphics. The project is close to 5 minutes in length, when I noticed the project effecting the performance of my computer I created 4 smaller projects.


I'm using the rotobrush to add back in the underside of the brim, a task which, initially, I didn't expect to be such a problem.

No issues at all with keying, so I duplicated the footage, and began roto brushing the brim at full resolution. For the most part, I've been advancing by 10 frames, which I understand will take longer to propagate, however any selection after the render is completely is leaving After Effects almost completely unresponsive for a minute or two.


Not sure what exactly is going on. I just finished a project last week and used the roto brush quite a bit and had absolutely no problems!


I read every article and post I found on the roto brush tool, as well as a handful of AE Optimization articles and videos.


Not sure what else you might need to know from me, but any input or advice would be great.

Also, if there is a better way to handle adding the underside of the brim back in please let me know. I've tried a few different options, and roto brushing seemed to be the best and quickest option until this!


Thanks a lot!


  • Currently Being Moderated
    May 14, 2013 2:28 PM   in reply to JoePV417

    You might find it helpful to use Keylight not to create a completed key, but to generate mattes.


    You could use two instances of the footage, use the lower layer to create the Edge Matte, and the upper layer to generate the core matte, readjusting Keylight to give you everything except the edges.  Nest this comp in a main comp, and use the nested comp as an Alpha Matte for a third instance of the footage.

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    May 14, 2013 4:50 PM   in reply to Dave LaRonde

    I would follow Dave's advice and create some mattes and then do some roto. This footage is going to take some work but it can be done. When I get back to the office I'll give the screenshot a closer look and post some suggestions.

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    May 14, 2013 11:36 PM   in reply to JoePV417

    Could be normal. RB works on detecting patterns and your footage overall looks a bit flat and due to the screen there are large uniform areas it may chew on. also you might consider actually cutting your footage in separate segments than just trimming them in AE. You could be seeing lots of delays due to file I/O and the RB looking beyond the in and out points...



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    May 15, 2013 6:15 AM   in reply to Rick Gerard

    It's hard to say what is causing the rotobrush show down but there may be an easy work around. Try something like this:

    Screen Shot 2013-05-14 at 10.26.31 PM.png

    I applied keylight to the footage, selected combined matte to give rotobrush a nice easy area to work in, then pre-composed the keyed footage and used RotoBrush on the layer to select the underside of the hat. I added a white solid behind the rotoed pre-comp and pre composed that to use as a track matte for the original footage. Keylight was also applied to the original footage but was only used to supress color. Here's the AEP. Maybe it will give you some ideas.

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