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I want a mash was able to catch light but was invisible on render. I want this effect to happen, but the plane was invisible. Is it possible? Or can I cast colored shadow? I need this in cycles. This question is not about "how to make an obect invisible" it's about how to make in catch light. enter image description here

Fore example

enter image description here

I need this happen

enter image description here

How can I get light accents without white face??? Do you see that light distributes unequally on shaped objects, how can I get only light fingerprint on transparent background?

enter image description here

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  • $\begingroup$ Check out the Light Path node.. maybe this tutorial will help $\endgroup$ – Robin Betts Mar 11 '19 at 18:47
  • $\begingroup$ Possible duplicate of How to make a cycles light emisson object invisible to the camera? $\endgroup$ – brockmann Mar 11 '19 at 19:14
  • $\begingroup$ @brockmann no, compared to that post I need the cube to be invisible but refract\reflect the light. $\endgroup$ – mevsme Mar 11 '19 at 19:27
  • $\begingroup$ Restrict the visibility to camera in Ray visibility, or use a light path node and Is Camera ray to control the mix between transparent and emission shader/ Read the following link: How can I make an object invisible when I render in Cycles? $\endgroup$ – user1853 Mar 11 '19 at 19:39
  • $\begingroup$ @cegaton there is no aswer for my question, remove the duplicate please. I need invisible for camera object was visible for light. imgur.com/xfMyDN4 at this picture it's invisible for the light. $\endgroup$ – mevsme Mar 11 '19 at 19:59
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final

I couldn't manage to make this "light catcher" using nodes but as a workaround or just alternate method you can use Baking. For this answer I'm using Blender 2.80 Beta and Cycles but the workflow is the same as in 2.79b.

Scene setup for baking

scene_setup

  1. Background needs to be black.
  2. Light should be fully white - you can change color of it after bake.
  3. Object may be simple Diffuse - needs to be UV Unwrapped.

Baking

bake

Bake Type - Diffuse with Influence Direct.

You should get a map like this:

bake_map

Using it

baked

Now you can use baked map as a mask to combine Transparent shader with another of your likeness. Color Ramp is for fine tuning mask strength.

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  • $\begingroup$ @sgslav Thanks a lot, mate! I think this is it! $\endgroup$ – mevsme Mar 12 '19 at 21:20

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