7 Replies Latest reply on Jun 24, 2014 8:36 AM by Dave LaRonde

    Trying to matte a background image with a PNG with transparency / partial transparency

    RP_Schmidt Level 1

      Hello everyone.


      Here is the scenario;


      1. I have a PNG sequence rendered from a 3d program. The sequence includes a landscape that is partially transparent and has no background image or color. In the animation, anything that is not the landscape is 100% transparent, while the landscape is partially transparent.
      2. I have a background that I want to put behind the PNG sequence but I don't want the background to be visible through the landscape portion of the sequence, only the portion that is 100% transparent.


      I have tried several different methods, but because the landscape is partially transparent, using a track matte (alpha or alpha inverted) or blend mode (like stencil alpha) does not give me the results I am looking for.


      What I am looking for is a way to matte (or mask) the background image with only the portion of the PNG that is 100% transparent. That way, the background image will not show through the semi-transparent landscape, but will be visible in the portion that is 100% transparent.


      I would like to find a reasonable solution in After Effects as opposed to re-rendering the 3d sequence with the objects being unseen by the camera and the background present. The landscape scene itself took a considerable amount of time to render (120+ hours) and I would like to avoid that kind of delay in my project.


      I thank you all in advance for your consideration.