God Rays - Vray for Maya

#1

Hi,

I want to make a simple 3d god ray in v-ray without having to composite it in.

I have used the fog in vray but none of it achieves that nice beam of light look. Can anyone give me a quick rundown? Thanks.

#2

could you show a pic of what results you are getting now?

#3

something like this?

http://www.rwnaturenotes.net/wp-content/uploads/2009/06/sun_and_fog.jpg

http://3.bp.blogspot.com/-qq3GlE2PbuA/TngEBj0JbpI/AAAAAAAABEQ/UizvEHF_nZE/s640/god+rays+1.jpg

I am curious too how to do it with vray for maya? I am testing vray env fog but no success when it is an outside scene. when I create a box with a hole for instance, I can get the effect. does somebody knows how to do it?

thanks

stussy

#4

You’ll want to use a very bright spotlight with some sort of high contrast texture, or a really distant spot with a very narrow cone over detailed geo to get that kind of effect. Directional would work too, but a spot will focus the effect and be a bit more efficient overall.

Edit: Directionality to your light is paramount. Rect lights/dome lights cast their rays in a super wide angle and won’t come into focus in the way you’re looking for.

I’d suggest using VRayEnvironmentFog (in your render globals) and start the view distance at something like 5000 with a very low density and work your way up slowly. It might be tempting, but don’t allow GI to interact with the fog at first (on the EnvFog node).

Using a spot means that you probably don’t want it to contribute to specular if you’re working on an animation… infinitely small source + adaptive DMC = fireflies in motion usually.

I’ve had rather good luck getting the type of result you’re looking for using black & white caustic textures with EnvFog.

Hope this helps,

–T

#5

cool, that sound convincing to me :slight_smile: I will need it for stills and render it as a render element pass. That works fine in PS.
As a light source I am using the Vray Sun. But I will test a spot light too since it is a separate pass. For Color Mapping I am using Reinhard

Adaptive DMC ? I have the feeling Adaptive Subdivisions seems to be better, at least for stills for sure.

I will do some test this evening with a spot light

cheers

flo

#6

a god ray is actually shadows cast by geometry inside a volume. if you want to physically simulate it, use fog or fluids and turn shadowing on for the fluids.

although i’m not sure if v-ray supports fluid shadows…

#7

It does, at leas i know it does in 3DS max.

#8

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