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enter image description here

I am working on a shot of a car sitting in a plane integrated into a video I shoot.

When I rendered the image sequence I separated the shadow from the car (when I was rendering the Car itself I disabled the Shadow catcher plane and vice versa) to give me more flexibility in compositing. Then I imported the shadow sequence and the car sequence in After effects. When I am trying to darken the shadows more using curves the shadow is not affected with any change. I imported the sequence in blender compositor but the same thing happens.

Does anyone have an idea to solve this issue?

strong text

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  • $\begingroup$ Related to Blender - please give as screenshot or better simplified blend file of composition via blend-exchange.giantcowfilms.com to see setup. Thank you $\endgroup$
    – vklidu
    Jun 21, 2020 at 20:54
  • $\begingroup$ Thanks for your reply I uploaded the file $\endgroup$
    – Andrew
    Jun 21, 2020 at 21:02
  • $\begingroup$ What format did you use to export the shadow? $\endgroup$
    – susu
    Jun 21, 2020 at 21:15
  • $\begingroup$ I tried PNG and EXR but both are not working $\endgroup$
    – Andrew
    Jun 21, 2020 at 21:16
  • $\begingroup$ Are you multiplying the shadow as transfer mode? $\endgroup$
    – susu
    Jun 21, 2020 at 21:24

2 Answers 2

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The correct way is to export the shadow pass. If you don't wanna do this, create a "Shadow pass" like with a white background so curve have something between black and white and not only black and alpha. after that you should be able to edit the shadow and add this to your scene using a Multiply blend mode.

enter image description here

Hope that helps.

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    $\begingroup$ If you multiply the pixel values by let's say 0.5, all white/grey areas will effect the color values of the clip. Why do you think this is one good approach? $\endgroup$
    – brockmann
    Jun 21, 2020 at 22:00
  • $\begingroup$ I think this is a very smart way it works perfectly with me thank you for your response $\endgroup$
    – Andrew
    Jun 21, 2020 at 22:29
  • $\begingroup$ @Emir May I ask you for more details? I mean whole node tree - how to combine with footage? I also got "footage" influnced (brighter/darker) when I changed RGB Curvature. Thank you $\endgroup$
    – vklidu
    Jun 21, 2020 at 22:39
  • $\begingroup$ @brockmann This was just an example about how to manipulate a shadow with alpha, obviously you set the curve as in the image you will get balck, grey and white, you need to manipulate the curve, probrably close to the center. things that worked for me, I am very sorry if i nsulted you with this answer, that was not my intention. just trying to help. $\endgroup$
    – Emir
    Jun 22, 2020 at 0:48
  • $\begingroup$ @vklidu if you render this you can use something like After effect and combine this with your footage. $\endgroup$
    – Emir
    Jun 22, 2020 at 0:50
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I would say, you should affect Alpha channel not the RGB values for correct result.

  • connect EXR alpha channel to RGB Curve node
  • to combine image and alpha channel back add Set Alpha node

enter image description here RGB channels of Shadow Catcher probably does not contain any information at all.

Note: for images like PNG (without separate alpha channel listed) you can use Separate RGB node.

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    $\begingroup$ Yes, it works thank you so much :) $\endgroup$
    – Andrew
    Jun 21, 2020 at 22:02
  • $\begingroup$ Yes, of course, I did already I marked the up arrow $\endgroup$
    – Andrew
    Jun 21, 2020 at 22:14
  • $\begingroup$ I did that thank you again :) $\endgroup$
    – Andrew
    Jun 21, 2020 at 22:30

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