Rotoscoping Strategies

topic posted Wed, June 1, 2005 - 4:12 PM by  Chris
I've been working on a bit of footage trying to isolate one bit of it for later compositing over other footage. So far I've been drawing a mask with the bezier pen tool. It's going pretty slow. Can anybody recommend not only other ways of doing this, but also what the proper workflow might be to approach something like this. For what it's worth, I know the bezier pen tool pretty well so I think I just look to that immediately because it's familiar. I still don't have an idea about proper workflow, however.

Thanks, Chris
posted by:
Los Angeles
  • Re: Rotoscoping Strategies

    Wed, June 1, 2005 - 5:32 PM
    You could render the clip you want to rotoscope as a filmstrip and take it into Photoshop, some people can work faster in Photoshop.

    There are some programs out there that do rotoscoping as well, there's one called Rotoshop, you might want to look into something like that as well.
    • Re: Rotoscoping Strategies

      Wed, June 1, 2005 - 5:53 PM
      silhouette roto is supposed to be pretty amazing and has just been launched. It works as aplugin for AE and also standalone.

      This is a snip from their website.


      silhouette roto allows you to quickly create sophisticated animated mattes using Rational B-spline, NURB or Bezier shapes. Intelligent design and easy-to-use tools, such as variable edge softness on a point by point basis and realistic motion blur, assist you in creating shape animations. Integrated motion tracking makes the normally tedious task of rotoscoping a breeze.

      Unlimited number of animated B-Spline or Bezier shapes
      Integrated Motion Tracker that can apply motion data to points or shapes
      Shape assisted motion tracking
      Move, scale, rotate, shear, and corner pin shapes
      Point-by-Point variable edge softness
      Realistic motion blur
      Animation changes for points and shapes across all keyframes or a selection of keyframes
      Independent shape viewing
      User-definable names for each shape
      Preview shape animation over image
      Composite Preview
      Multi-processor support
      OpenGL® accelerated animation engine
      Mask interchange with Adobe® After Effects®
      Import Elastic Reality® and Pinnacle Commotion Shapes
      Export Discreet® Combustion®, Flint®, Flame®, Inferno®, Smoke® and Fire® GMask shapes
      Export Apple Shake 3.5 Shapes

      Price: $495.00

    • Re: Rotoscoping Strategies

      Sun, August 13, 2006 - 6:52 AM
      the key to rotoscoping is to do as little as possible (overworked curves chatter like crazy):
      fewest points, fewest keyframes
      worst thing you could do is set initial keys every second or so, or start at the beginning and do every frame
      what you want to do is find where the motion has extremes, which i call nodes just for brevity:
      drop a key at the top of a movement, or just before it curves right. Start with the big nodes, then work towards smaller, lesser changes.
      then go in and tween as needed. you generally do not need keys for every frame.

      more paths you use, the less keying one area will affect another. you want to be able to focus your adjustments on one area at a time. if you're trying to adjust the whole thing on each key, I guarantee it will chatter, and you make way more work for yourself.

      where you have two curves crossing and moving, you'll often get a better result by dividing it into two separate paths
      for example an arm crossing the edge of a shirt

      you'll also want to work at at least 200%, even bigger for more detail. move back and forth in time to see how your path moves with the changing pixels

      basic rule of changing number of points:
      do it only on adjacent keyframes, otherwise you risk strange tweening
      I disagree with the earlier suggestion to keep the max number of needed points on every key; once you have excess points congealed into a little blob, turn off "Preserve Constant Vertex Count" in Prefs, and delete them on the next keyframe. if it isn't turned off, you'll delete those points throughout the layer.

      I usually do all my rotoscoping on a solid layer, or even on a couple of solid layers, then set that all up as the alpha matte to the original. this way you can use areas of the original that keying works for.

      put a contrasting solid layer under it once you've turned on the matting, so you can check the edges. if the bg you roto'ed out was black, then check it over a white layer, etc.

      if your footage was originally shot on film (which you'll see because every fourth and fifth frame are identical, then you can "remove pulldown", which leaves you with 24 frames a second to work on. Otherwise you may need to make a 59.94 fps comp and roto 60 goddamn frames per second, pfffffft. when do we ever lose this primitive fields crap, and all the 601 colorspace issues, hurry up losers, damn.
  • Re: Rotoscoping Strategies

    Thu, June 2, 2005 - 7:26 PM
    If you don't have some kind of key color, you're pretymuch stuck and just have to do it. (that's why they offshore this stuff to china)

    My advice is to plan out all the points you are going to need in the most complicated frame of the footage. Example, I have a talking head a few points to define, but part way through, they raise their hands up. Draw your initial mask on the frame where you need the most points to define the mask. Then move back to frame 1 and click the stopwatch of mask shape to turn on recording frames for the mask.

    You may think on your first frame you have too many points to manage, but go ahead and find them a calm resting place in your mask. Then when you need them, they will be there.

    I found it is more of a pain to add new points to a mask after you have already started animating it. It is better to simply have a few point laying aroud when you need to define extra areas that appear.

    My 2 cents,

    Good luck!
    • Re: Rotoscoping Strategies

      Fri, June 3, 2005 - 10:51 AM
      I concur; look for the frame with the most detail and 'scope that one. The only real alternative is to call up the client and pretend your power has gone out, then drink a bunch of coffee and tribe all day.
      • Re: Rotoscoping Strategies

        Fri, June 3, 2005 - 12:13 PM
        draw separate masks for each part instead of one huge one around the whole thing.
        • Re: Rotoscoping Strategies

          Fri, June 3, 2005 - 5:39 PM
          and the less points you can get away with, the better!

          also, sometimes if there's lots of action, it's easier to roto out segments, rather than try to animate the same mask thruout the entire clip
        • Re: Rotoscoping Strategies

          Sat, June 4, 2005 - 1:41 AM
          To expand on what Mishka has said....create simple shapes (ovals etc) to cut out portions of your image, for instance if I were working on an arm, I might have one shape for the forearm, and another for the upper arm, depending on the amount of definition shown, possibly a shape or two to subtract or add to show the muscles.

          Another piece of advice, would be to not go down the timeline adjusting the mask every frame, instead pick a range, adjust the starting frame, the end frame and then pick a spot in the middle, the points you choose are arbitrary, sometimes simply based on number of frames, but sometimes based on the amount or type of movement. Proceed by further subdividing the range and adding in keyframes until the mask follows the shape you need.

          • Re: Rotoscoping Strategies

            Sat, June 4, 2005 - 3:54 PM
            In choosing your frames.... look for where momentum shifts. for example... if someone is moving from side to side. do the furthest side motions then clean up the next largest motion in between. until all frames match - that's you're best shot at smooth motion roto.
  • Re: Rotoscoping Strategies

    Wed, June 8, 2005 - 3:10 PM
    Thanks everybody for all the great advice. I ended up working in quite a few of the suggestions. I created three separate masks at one second intervals and then filled in at half-second intervals and tweaked where necessary. After that, I keyed just the top of the hair on the subject using a color key and then added that to the other rotoscoped stuff. I'm still tweaking, but it's definitely starting to take shape. Thanks again. --CC
    • Re: Rotoscoping Strategies

      Sat, June 18, 2005 - 12:57 PM
      Welcome to the world of crampy hand.
      • Re: Rotoscoping Strategies

        Sun, June 25, 2006 - 8:11 PM
        I need some help?! I am working on a full body dance shot in After Effects. I am roto-ing her for fun. Not really, I want to use the mask in a silhouette. Ok, my question- why the rough edges? So far it looks almost pixelated on the edges. I'm afraid bluring or feathering will look like I don't have a clue. If that may be true, I don't want it to look that way.

  • Re: Rotoscoping Strategies

    Sat, August 12, 2006 - 2:11 PM
    Paying attention to the momentum is the way to go - at least thats what all the tutorials say:)
    that way you can take advantage of the "tweening".
    if it doesn't look perfect, you can just go back and add additional keyframes..
  • Re: Rotoscoping Strategies

    Sun, August 13, 2006 - 6:54 AM
    and how many other people have, after a long week of rotoing (the sheetrocking job of the post-production world), tried to roto passing taxicabs, or your bottle of beer...or spent long nights dreaming of dragging paths across counties, setting keyframes in vineyards and football stadiums, oh my god it just crushes your brain...

    but damn, for $500/day, I am happy to have my brain crushed... a point...
  • Re: Rotoscoping Strategies

    Sun, August 13, 2006 - 2:06 PM
    "Effects Corner" Did a podcast you can find I believe at the itunes store... two parts...

    Rotoscoping - Part 1 21:51 1/23/06 Rotoscoping for Animation and Visual Effects.

    Rotoscoping - Part 2 21:00 1/25/06 Rotoscoping - Part 2

    I didn't watch it, so I can't vouch for the quality - but's it's video and it's free.

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