3 Replies Latest reply on Jun 15, 2009 12:00 AM by stuie2

    Bouncing Mask


      Long story short, I forgot my greenscreen to shoot some clips. Because of time contraints, I shot the clips. They're short, so I decided to do it the hard way and mask my subjects since they were stationary. The camera was on a rail with only a right to left motion, but there were bumps as it traveled. I stabilized the clips on the Y - axis to get rid of the bumps. However, when I applied the mask, the clip was stabil, but the mask was bumping up and down. Why is this? I thought that once the clip was stabilized, then mask applied, they would both travel smoothly along the X - axis without any up and down on the Y - axis.

        • 1. Re: Bouncing Mask
          Mylenium Most Valuable Participant

          Think of it: Masks are relative to the layer, not the comp. Applying the mask directly to a stabilized layer therefore naturally also moves the mask, which is what happens - the pixels seem to be stationary, but in fact the layer moves all the time. Simply add a solid on top and use it as a matte, then do all your masking work on the solid. Or alternatively, pre-compose the stabilized shot without the masks, then mask the pre-comp layer.



          • 2. Re: Bouncing Mask
            stuie2 Level 1

            I did as you suggested, I precomped the stabilized layer, then applied the mask to it. I still get the same results, the mask keeps bouncing up and down while the video is smooth. Is there something that I;m missing on the precompositing stage?

            • 3. Re: Bouncing Mask
              stuie2 Level 1

              Oooops, I see what I did wrong now. I forgot to make the precomposotion with the stabilization included. Note to self, read the options that you get when saving a precomp file. Thanks for your help, it works now.