3 Replies Latest reply on Sep 20, 2011 9:21 AM by TheFosterHouse

    AfterEffects CS5 Rotobrush/Render Problem


      Hey guys,

      So I'm having a problem with a Rotoscope I'm rendering out of AE CS5 for a client/internship (ie: starwars/E.T./Planet Terror/Space Cowboys).

      I'm on Mac OSX. 10.5.8 2.8 GHz Intel Core 2 Duo.

      The goal of this shot was to put Angel wings behind the actor, using the  Rotobrush tool in AE to remove the actor and get the wings behind him.

      I've successfully made an initial draft. Using position, opacity and  scaling in AE. And have put the wings behind the actor (not shown above)

      Here is my issue:
      The roto (above) appears fine working IN aftereffects. But when I render  the wings overlap the arms on a couple frames, as you can see here: http://www.youtube.com/watch?v=2pFk0B4mLmA

      This is a 1st draft. In AE those 'overlaps' of the wings over the arms don't appear. I've tried adjusting/redoing those frames with the rotobrush to no avail.  I still get the same  result.
      Do any of you know what the problem could be? Any help, suggestions would be incredibly appreciated.


        • 1. Re: AfterEffects CS5 Rotobrush/Render Problem
          Mylenium Most Valuable Participant

          Interlaced footage with incorrect/unsuitable footage interpretation would be my first guess. And working at half res naturally qualifies as equally bad - by suppressing evey second pixel, you inevitably the result of the analysis is different than it woudl be at full res. in fact that's why you should get a warning about it when applying the RB the first time...



          • 2. Re: AfterEffects CS5 Rotobrush/Render Problem
            Navarro Parker Level 3

            Depending on the shot (if he flaps his arms or not), this should be pretty easy to do with Mocha. The lines are pretty clean and well defined.


            Draw a shape for each bicep. Motion track. Draw a shape for the chest. Motion track. Draw a shape for the shoulders. Motion track. Draw more shapes to fill out the remaining shapes and attach to the tracked motion. Adjust as needed. The key to good rotoscoping is not to try to do everything in one shape.

            • 3. Re: AfterEffects CS5 Rotobrush/Render Problem
              TheFosterHouse Level 1

              Navarrow is right about roto. whether you use Mocha or just roto by hand in AE, this shot shouldn't give much trouble. If you're set on using the roto brush, you'll probably need to go through the footage a bit and re-establish FG and BG to help the Roto brush find the edges. Remember that the Roto brush relies on contrast to work properly.