I want to pan a plane in front of many 3D objects and make the plane material cause the render to make a PNG transparency instead of showing the plane. In cycles.

Can I do that in the initial render, without using Chroma Key in post?

  • 2
    $\begingroup$ Are you looking for something like holdout? This would make the area covered by the object(s) transparent, if Render Properties > Film > Transparent is enabled. $\endgroup$ Commented Oct 24, 2020 at 12:55
  • $\begingroup$ Recommend render to OpenEXR especially when dealing with alpha: blender.stackexchange.com/a/106671/31447 $\endgroup$
    – brockmann
    Commented Oct 24, 2020 at 13:21
  • $\begingroup$ There is no need to use chroma key with digital files. Chroma key works in camera generated images, since there is no way to capture alpha with a camera in real life. For CGI you can always export the channel alpha directly, either as part of the file, or as a mask. Using PNG to store transparency quite is limited, as it does not support associated alpha, and cannot transport pixels that are luminous and transparent at the same time (like fire, glows, reflections on glass, etc). EXR is a much more robust file format designed explicitly for postproduction and compositing. $\endgroup$
    – susu
    Commented Oct 24, 2020 at 19:12
  • $\begingroup$ @RobertGützkow Yes! holdout, I word I didn't even know. Thank you! $\endgroup$ Commented Oct 25, 2020 at 16:46


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