It's hard to explain this. The way I'm visualising it is by thinking of an invisible object which reflects light.

enter image description here

Let's say we this cube here with one face of it being lit up with a blue spotlight.

Now, let's treat the patch of blue light on the face of the cube as another discrete object (I understand it's physically impossible but bear with me).

I want to be able to keep that patch of blue light while making the cube disappear.

What I visualize in my head is a patch of blue light hovering. My ultimate goal is to capture lighting information.

I hope this makes a little more sense.

  • $\begingroup$ Which render engine are you targeting? [Cycles, Internal ... ] $\endgroup$ – Leander Mar 28 '18 at 19:37
  • $\begingroup$ This is pretty vague and contradicting. Could you post some reference images? $\endgroup$ – Duarte Farrajota Ramos Mar 28 '18 at 22:45
  • $\begingroup$ Cycles and it's hard to get a reference for this. I'll try and explain more in an edit. $\endgroup$ – user3927312 Mar 28 '18 at 22:48
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    $\begingroup$ Perhaps it would help if you could elaborate on why you want this/what you want to use this information for? You might be able to capture the lighting information you want by using render passes. $\endgroup$ – gandalf3 Mar 28 '18 at 23:48
  • $\begingroup$ I want to see if I can overlay it on an image and make synthetic lights. $\endgroup$ – user3927312 Mar 29 '18 at 0:34

In the object properties tab of the properties window, there is a section titled "Cycles Settings". If you uncheck the box "camera" under "Ray Visibility", that object will disappear from the render but still reflect light and cast shadows. enter image description here

  • $\begingroup$ This wasn't what I wanted but thanks anyway. $\endgroup$ – user3927312 Apr 12 '18 at 2:11
  • $\begingroup$ @dixiepig Creating the setup described in the image of the question. Toggling the Camera visibility makes the cube and its reflection(of the light) invisible to the camera(including render). $\endgroup$ – rob May 4 '18 at 11:33

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