3 Replies Latest reply on Mar 7, 2010 3:12 AM by Mylenium

    Creating a circular path for a mask

    ECS_1 Level 1

      hi all

       

      I have a eliptical mask which I want to move around the screen clockwise in a circular fashion.

       

      So far I have managed to create four keyframes and using the "easy ease" I can get the mask to move around the screen in a smooth diamond pattern, but it needs to be circular. I have tried adding additional keyframes between the diamond points, to "round off" the motion, but it doesn't really work. The movement is stilted.

       

      Is there an easier way to create this mask path?

       

      thks

        • 1. Re: Creating a circular path for a mask
          Rick Gerard Adobe Community Professional & MVP

          Mask vertices move is a straight line between key frames. This is what's causing your circle to travel in a diamond path. Masks also change shape if you rotate the mask. The same thing causes the problem. Mask vertices always travel in a straight line between keyframes. There's a mask interpolation tool that helps when masks rotate, but it won't help in situation. There's no way to create, see or edit a bezier (curved) motion path for a mask vertex.

           

          A better approach would be to use a elliptical shape layer instead of a mask. Position the shape layer on the planned path, then use the transform property of the shape layer to do the rotation. Shape layer behave much better than masks.

           

          Now if you need to use the circle to mask or cut out an area in a footage layer then just place it above that layer and set it as an alpha track matte.

           

          Maybe a picture would help.

           

          ShapeProperties.png

           

          The Ellipse 1 has transform properties which position it on the shape layer. If the Transform Ellipse 1 position is 0, 0 then it is at the center of the Shape layer. This one is 142 pixels left of center and 65 pixels above.

           

          The second Transform property is for the whole layer. This is the one you would use to rotate the ellipse. If you adjust the position of the mask layer you'll also be able to see and edit the bezier path for the motion.

           

          I hope this helps.

          • 2. Re: Creating a circular path for a mask
            Mylenium Most Valuable Participant

            Aside from Ricks wonderful suggestion, the whole problem could probably just as well have been solved with rotating the layer and using it as a matte, rather than trying to animate the mask...

             

            Mylenium

            • 3. Re: Creating a circular path for a mask
              ECS_1 Level 1

              Thanks both very much, will have a good look at this tomorrow