3 Replies Latest reply on Apr 8, 2010 11:09 AM by Szalam

    Experimenting with masks [newbie]



      Hello, I'm a newbie in AE trying to experiment with it.


      What I'm experimenting with is a short video in which a person (me) opens the door just to find himself on the other side walking in. Therefore I've shot the following two scenes (the camera was in identical position/location):

      Scene A: Myself entering the scene, walking to the door, opening the door (steping aside), waiting a bit, closing the door, walking out of the scene. I have my back on the camera during this scene as the camera is facing the (inside) of the door.

      Scene B: Myself in front of the open door (facing the camera as I'm standing on the outside of the door), stepping through the open door and walking out of the scene.


      I have tried experimenting with masks, but I have a conceptual problem regarding what and when to mask. Initially I thought to substract-mask the whole door area in Scene A just when the door starts to open and add-mask the door area of Scene B. This seems to work prety much ok (later on I'll need to also mask the path of the person walking in I guess) but the problem is that the mask I apply on Scene A is "there" from the beginning of the clip, which is obviously wrong as it substract-masks even myself walking to open the door. From what I've read on the forum, it's not possible to selectively turn on/off a mask at certain keyframes, therefore how do you think I should go about this? Is my approach ok or I'm looking at it in a totally wrong way?


      thanks in advance!


        • 1. Re: Experimenting with masks [newbie]
          Szalam Adobe Community Professional & MVP

          One easy way to do it would be to use three layers. One for each copy of you and one blank plate. You wouldn't have to make very precise masks around the two of you except for the frames where you cross yourself.


          Actually, you can "selectively turn masks on and off". Just set a keyframe for your mask shape, go one frame ahead and move the entire mask out of the comp's viewing area (or outside of the layer's bounding box).


          What you are doing is called rotoscoping and this page has a lot of useful information and links to helpful tutorials.

          1 person found this helpful
          • 2. Re: Experimenting with masks [newbie]
            NMichas Level 1

            Thanks a lot for the prompt answer!


            I can get my two scenes and draw the layers around myself (there is no cross-over, as on Scene A I'm stepping aside the door on purpose - i.e. so that the other myself can pass through without crossing). What mask-type should the two masks that I'll draw on myself (i.e. add, subtract, etc.)? And what should contain the "blank plate" layer and on which scene should I create it? Sorry if I miss some of the terminology here


            I'm going through various tutorials trying to learn, thanks a lot for the links. One additional quick question: Do I understand correctly than in Mocha you can only track surfaces defined only by 4 points? I say this because I see that you can define a spline of any shape but it's the actual "surface" you define later on within this spline that is eventually being tracked.




            • 3. Re: Experimenting with masks [newbie]
              Szalam Adobe Community Professional & MVP

              All your Mocha answers should be found here.


              Since you're so new, I would highly suggest you go here and follow ALL the links therin. Once you're done with all of it, you will be much less frustrated and have much more fun with AE. It's got a ton of great resources including the spectacular tutorials from VideoCopilot.net.