I shot a video in a chroma room (object in front of green background), after I have eliminated the green (masked away). Please, can someone explain how I will cast the shadow of the object on my new background? Thank you in advance.

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    $\begingroup$ Are you sure this question is animation nodes related? $\endgroup$ Sep 26, 2016 at 2:12
  • $\begingroup$ I am working on music video, not animation. I just created a hall with blender as a background. $\endgroup$
    – myteasax
    Sep 26, 2016 at 2:16
  • $\begingroup$ Not sure about the way you did. If you use the video image sequence as texture on a plane, then it is possible to cast shadow, which works for Cycles and BI. Anyway, more info needed to undersand your question better. $\endgroup$ Sep 26, 2016 at 2:19
  • $\begingroup$ If I use it as a texture, do u sure I will have a good output? $\endgroup$
    – myteasax
    Sep 26, 2016 at 2:30
  • $\begingroup$ Here is a simple material setup for Cycles. FYI. $\endgroup$ Sep 26, 2016 at 2:50

1 Answer 1


Once you have your subject cut out, you can use its alpha channel to make a shadow layer with the compositor:

enter image description here

  • After the color keying is taken care of, use the Separate RGBA node to get the alpha channel.

  • Run it through a translate node so you can move the shadow.

  • The alpha channel will need to be inverted with an invert node.

  • Multiply the shadow with the background and use the multiply factor to control the opacity of the shadow.

  • Run the shadow-background and color key results through an alpha over node to put the color keyed result over the background-shadow.


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