Author Topic: Exclude a light from CoronaVolumeMtl  (Read 1612 times)

2020-10-01, 13:28:36

balatschaka

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Hello Ladies and Gentlemen,

in my animation I have a plane light with the sole purpose of beeing a Rim light to the character dancing. It is not visible directly and the only included object in the light is the character model.
My problem, as you can see in the attached rendering is, that it is still interacting with CoronaVolumeMtl.

Is there something I'am missing? Does anybody have an idea how to deal with it?


Thank you

2020-10-01, 15:51:23
Reply #1

TomG

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Some questions -

Is the volumetric material applied to geometry, rather than used as a Global Environment?
Since I don't know the scene set up, are you certain that it's the light that is showing up in the volume, and not some bounced light from another object? See attached images, even with the light excluded, the light from the ground plane still show up in the volumetric material (first image has no excludes, second has the volumetric cube excluded, same result as only including the ground plane)



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2020-10-01, 16:06:27
Reply #2

balatschaka

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Hey thank you for your reply.
The CoronaVolumeMtl is in the global slot and putting it on a Box for example has the same effect.
I uploaded a render with just the light isolated, without anything what could interfere. The volume material makes the light visible.

I kind of wish the CoronaLight had in its "Visibility" section the option to make it not visibile to volume material.

Thanks

2020-10-01, 16:17:41
Reply #3

TomG

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It would definitely have to be on an object for the exclude / include list to work (not in the global slot). Can you upload the scene, because for me in my super simple scene, the light definitely has no effect if an include or exclude list is used to remove the cube with the Volume Material from the effects of the light (I'd upload the render, but it's just black as soon as I take the ground plane out :) )
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2020-10-02, 08:34:03
Reply #4

balatschaka

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Here you go and thank you.

2020-10-02, 14:19:12
Reply #5

TomG

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Confirming it here - the brighter lights, and the Directionality in the Scattering in your scene brings it out more. The Exclude is definitely excluding something, as most of the scattering in the volume disappears, but right enough something remains. We will have a look into it!

Didn't find a workaround for now either, tried out all sorts of things, but other than lowering the scattering directionality in the volume material (which only reduces the effect, doesn't really negate it, plus it would change how the scattering looks), I couldn't see a way to avoid it.

(Internal ID=73135811)
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2020-10-02, 14:39:57
Reply #6

balatschaka

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I'am not sure if it is relevant, but I had another issue with volumetrics and visibility in the beginning of this project..
If you use Volumetric scattering in CoronaMtl and set the Object Visibility for example to zero, then the object will become invisible (diffuse) but the volume effect of it will stay visible. See attachments.

Thanks and Good Luck
Andrej

2020-10-02, 14:47:44
Reply #7

TomG

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That one doesn't sound like an issue Andrej, it's how volumetrics in a regular CoronaMtl are meant to work - you need to have some sort of transparency for the volumetric effect to show up, with an Opacity of 0 being quite common, and it would be expected the volumetric effects not only still show up, but show up most clearly under that setting as there is no other surface effect (diffuse, reflectivity, etc) shown. You can also look into using Translucency or Refraction as other ways of making the object transparent so that the volumetrics can show up.

Unless I am misunderstanding what you mean :)
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2020-10-02, 15:11:45
Reply #8

balatschaka

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Yes I got that much but Opacity, Refraction and Translucency are attributes on a material level while the visibility(Object Properties) which Iam talking about is on a object level and is definitely not a physical property. Should the volume effect not become invisible together with the object?

2020-10-02, 15:36:20
Reply #9

TomG

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Ah you mean the Max Object Properties Visibility. Right now that seems to act exactly the same as Opacity in the material, which to me would make sense. You can actually set up the volumetrics in the CoronaMtl, leave Opacity, Translucency etc so that everything is solid, and then set the Object Property Visibility to 0, and you get the volume effect the same as if Opacity had been set to 0. To me, that does seem consistent.

You would control the transparency of the volumetric effect through the volumetric settings themselves.
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