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I'm using Blender 2.83 with Cycles and I'm an absolute newbie to both.

I'd like to visualize light rays in a part of the scene (like godrays).

For this I put an object using volume scatter material into the scene.

This works, however the light intensity decreases, as light passes through the volume scatter material (due to scattering, apparently), and the volume scatter object casts a "half-shadow" onto the objects behind. Both is undesired, i.e.:

I'd be happy to make the volume scatter material not reduce the intensity of passing light. Is it possible? Or any better approach? Thanks a lot!

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  • $\begingroup$ Does turning off shadows for that object work? $\endgroup$ Aug 1 '20 at 23:48
  • $\begingroup$ Once I uncheck Shadow in Ray Visibility in Object Properties it really stops to cast shadow onto an object behind, but the object inside of it turn black and the scattered light is no longer visible. $\endgroup$
    – kc_
    Aug 2 '20 at 0:30
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Volume scatter will always make your lights seem darker. So you can make the lights brighter until you get the level you want.

You can animate the density.

$0$ density will make the volume scatter transparent, then bring up the value when you need the volumetric lighting.

As an alternative don't use volume scattering in the world, but on an object with volume scatter as voume, in a way in which you get the rays as you want, but not on the rest of the scene.

Another alternative is to disable ray visibility on light so that is invisible to Volume Scatter.

enter image description here

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  • $\begingroup$ Thank you, actually it IS what I am doing, I don't use volume scattering in the world but rather indeed on an object with volume scatter as volume. But I want exactly, that this object does not cast "shadow" (I understand, it's not a shadow by light absorption or quenching, but by dispersion of part of the light). Strictly physically I want that each point in the "scattering" volume emits light visible only to a camera, with intensity proportional to the lamp light intensity passing through that point, and without influence on (=reduction of) the incident (passing-through) light. $\endgroup$
    – kc_
    Aug 2 '20 at 9:05
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As a compromise workaround I set a very low density of the volume scatter material, then a very high intensity of the lamp to have the scatter light visible, and very dark colors for all other objects in the scene, so that they are nor overexposed. But is not there any less ugly and more elegant solution available??

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