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CharlesPeterson
Participant
June 1, 2010
Question

Rotobrush to MASKS

  • June 1, 2010
  • 4 replies
  • 49768 views

Ok,

In the help file it says you can copy rotobrush properties as a MASK.

How do you do this?

      This topic has been closed for replies.

      4 replies

      annachiara3625
      annachiara3625
      Participating Frequently
      July 15, 2020

      I am also trying to do this, and the reason is an obnoxious shortcut oriented workaround, but this is what software is supposed to do—make things that we used to do by hand on film efficient in video.

      I converted my video to extremely high contrast to get the rotoscope to better stick to the edges of my subject. Now I want to use that information to create a mask over the properly color balanced clip of the subject. Yes, this is a workaround to avoid frame-by-frame work, because this is what software is for! So I got the idea to export the entire video as png frames and create an automation task in photoshop and then convert the frames to black and alpha, then import png frames back into a video file for import into after effects to mask my very flat color-balanced video.

       

      So if it is that easy for me to achieve a workaround using an automated recorded action in photoshop why in the heck isn't this a function in after effects?

      R
      Community Expert
      Rick GerardCommunity Expert
      Community Expert
      August 4, 2020

      I almost always use a Rotobrushed layer as a track matte for the original footage or the replacement layer. There is nothing to it. Put the layer with Rotobrush applied above the layer you want to mask and choose Alpha or Alpha inverted for the mode.

        annachiara3625
        annachiara3625
        Participating Frequently
        September 8, 2020

        Clearly I am not good at after effects, I am an editor not an animator, but learning! 

        Thank you. Next step was to take that comp and put it in the comp over the background...that was so easy. Hahaha

        🙂

        T
        Thats My MO
        Participant
        August 13, 2019

        I know this post is quite old now, but I have found a great workaround to create a mask from a rotoscope. However, this will only apply to a single frame.

        1. Rotoscope a single frame in the layer view and freeze the frames before exiting to composition view.
          • The only visible part of the layer remaining should be the selected portions of your rotoscoped area.
        2. With that layer highlighted, go to the layer tab in the menu and select "Autotrace" to create a mask around the rotoscoped area.
        3. Copy the mask from the newly created shape layer to your rotoscoped layer.

        If you combine this with @todd_kopriva you should be able to use this to animate your mask. I have not tried this myself though.

        What it says in the Help document is this:

        "You can copy Roto Brush Path properties, and paste them into masks, shapes, and instances of the Paint effect, just like you can with other kinds of paths."

        That refers to the fact that you can copy the Roto Brush strokes' paths and paste them into mask path properties.

        However, I'm guessing that that's not what you're actually trying to do. I'm guessing that what you actually want is to take the transparency information that the Roto Brush effect creates as a matte and convert that to a mask that defines the same transparency information. To do that, you could use the Auto-trace command. The masks created by Auto-trace aren't usually what you want for conventional mask-animation rotoscoping work, though.

        So, the question is this: What are you trying to accomplish?

          rodolfop20506224
          rodolfop20506224
          Participant
          November 7, 2019

          Thanks! this helped me a lot! Hope you're having a good day :)!

          C
          CharlesPetersonAuthor
          Participant
          June 2, 2010

          Thanks for the information guys! I will try to have a little more patience with the RotoBrush and mess around with the settings.

          Todd_Kopriva
          Todd_Kopriva
          Inspiring
          June 1, 2010

          What it says in the Help document is this:

          "You can copy Roto Brush Path properties, and paste them into masks, shapes, and instances of the Paint effect, just like you can with other kinds of paths."

          That refers to the fact that you can copy the Roto Brush strokes' paths and paste them into mask path properties.

          However, I'm guessing that that's not what you're actually trying to do. I'm guessing that what you actually want is to take the transparency information that the Roto Brush effect creates as a matte and convert that to a mask that defines the same transparency information. To do that, you could use the Auto-trace command. The masks created by Auto-trace aren't usually what you want for conventional mask-animation rotoscoping work, though.

          So, the question is this: What are you trying to accomplish?

            C
            CharlesPetersonAuthor
            Participant
            June 1, 2010

            This is what I am trying to do. Maybe I am mis-understanding the help file.

            After I use the rotobrush, is there anyway to convert that information to a masl, so you can tweak difficult areas?

            I am roto an actor in front of a blank monitor that is black. When he crosses over the screen, his shadow almost matches the same color on the monitor and rotobrush has a hard time in this area. It does fine else where.

            So what I would like to do is that the rotobrush, convert it to a keyframe mask and make adjustments that way.

            Can you do that???

            R
            Community Expert
            Rick GerardCommunity Expert
            Community Expert
            June 2, 2010

            You might also try changing the Edge Detection setting (within the Propagation group) to see if it helps keep the edge on the shadow.


            The Roto Brush tool is a little funky to use. Path's aren't editable and in some cases, Mocha (part of CS5) or even drawing masks by hand will get you there quicker. I've successfully use Roto Brush on about eight or ten really difficult projects so far. Each was a real learning experience. I'm preparing a tutorial on the tool that I hope will make it a little easier to understand. Until then here's what I know.

            1. The strokes that you apply to the layer with the Roto Brush are vectors.
            2. The strokes define search areas, they do not create a mask directly.
            3. The stroke position is not animated over time.
            4. Roto Brush is, in most cases, faster by far than drawing masks.
            5. It seems to be a best practice to use Roto Brush on small sections of the image
            6. You must freeze Roto Brush before you return to the composition window or the footage will be re-interpretted and the roto will change.
            7. The vector paths you create do not seem to be useful for anything but Roto Brush.

            I hope this helps. For your application I think a combination of multiple uses of Roto Brush combined with some hand drawn masks may be the best option. Only one of my recent Roto projects was completed by using a single copy of the layer with a single application of Roto Brush.

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