5 Replies Latest reply on May 3, 2016 11:52 PM by Rick Gerard

    Mask question for a Newbie


      I've painstakingly masked about 500 frames (I couldn't get the tracker to work) and I'd like to drop a new video clip inside of that mask I've already set up, but it was the video clip itself that has the mask info/data/points.


      Question: Can I use the exact perimeters of the mask I created for another clip, or do I have to go through that process again?


      To help with a visual, Imagine footage of a moving ball. I'm playing another clip inside a mask that's moving with that ball. The mask is associated with the clip playing inside the ball, not the ball itself.


      I'd like to simply drop another clip inside the ball, but the mask data is with the first clip!


      Any help suggestions would be appreciated!

        • 1. Re: Mask question for a Newbie
          Szalam Adobe Community Professional & MVP

          There are a couple of ways to do this. One is to replace the footage that has the mask applied. Simply select your layer in the timeline panel then alt-drag (or opt-drag if you're using a Mac) footage from the project panel onto that layer in the timeline. It will replace the layer source and leave everything else (masks, effects, transform keyframes, etc.) on the layer.

          Alternatively, you can use your masked layer as a track matte for anything else.

          • 2. Re: Mask question for a Newbie
            madaneerg Level 1

            Thanks Szalam, I'll give this a try and report back!

            • 3. Re: Mask question for a Newbie
              madaneerg Level 1

              Ok, So replacing the footage worked like a charm! However, I can't move the footage around inside the mask - so I'd love to know how to use the layer that has the masks that change on almost every keyframe as a track matte. Is there a simple way to take that layer with all that data and turn it into a track matte?

              • 4. Re: Mask question for a Newbie
                Szalam Adobe Community Professional & MVP

                Yes. You're going to kick yourself with how simple it is.

                Use alpha channels, masks, and mattes in After Effects

                • 5. Re: Mask question for a Newbie
                  Rick Gerard Adobe Community Professional & MVP

                  If you went though 500 frames one frame at a time you probably did a bunch more work than you needed to do. You want to pick a frame where the motion changes direction to draw your first mask, press Alt/Option + m to set the first mask keyframe, then move down the timeline until the motion significantly changes direction and adjust your mask. Then you move down the timeline until the motion changes direction again and make another adjustment. When you get to the end you go back to the start of the clip and check half way between the keyframes to see if there are any adjustments that need to be made. Then you repeat this again and then start stepping through the timeline making small corrections as needed. Just the other day did a hand roto of the 40 frames that I needed to mask in a 10 second shot where a guy walked in front of a window. I only did the part of his body and arms that needed to cover the sign. I used one mask for the body and that one only needed 3 keyframes because the speed was pretty constant. I used two other masks for the moving arms and each of those masks only had about 4 or 5 keyframes. 40 frames rooted in about 2 minutes. Here is a basic tutorial that shows how to manually roto a subject. I stabilized the motion of the dog so that it was easier to work on the mask. For a lot of shots this is a very good idea. I almost always roto on a colored solid with the blend mode that lets me see though the footage so I can easily see the mask I'm making. You'll get the idea. Once you have a mask animated you can select the masks and save the animation as an animation preset or use the mask as a track matte for any other layer in the project. The two best suggestions I can give you are to only mask the frames and the areas in the frame that need masking for your composite. I can't tell how many times I've seen a project where an actors hand passes over something that needs to be fixed for a few frames and someone has rooted the entire actor for the full length of the clip. Enjoy. Before too long I'll have a series of compositing tutorials on line that will show you how to do this kind of thing in the most efficient manner.