VrayHDRI and God rays using environmentalFog question

[mhouse777]

Hi,
I have a simple scene with trees and bushes on a plane and i'm using an HDRI sky with sun image in the dome light.. I'm trying to get the God ray effect, but it doesn't seem to work (Vray sun does work although). The fog volume is just illuminated instead of broken into rays. the fog distance here is about 200m. I favor HDRI lighting for it's realism . Any ideas would be appreciated. Thanks.

[joconnell]

You have to have a really high range hdr with a very bright and sharp sun - not all hdris actually capture the full range of the sun so most won't give you the values you need for god rays. If you want to force your hdri then gamma it down so it's more contrasty and then turn the multiplier up. It might be worth having one dome light for the fog only and a second domelight for your scene with a non colour corrected hdr.

[mhouse777]

...if I use a separate dome light for the fog, would I have to exclude all the other objects in the scene? Btw, the environmental box gizmo that I have the fog in doesn't show up in the exclude options in the dome light, so I cant exclude it in the first dome light.

[joconnell]

I think you can choose which lights affect fog in the environment panel - there's a "use all lights" tickbox beside where you picked your environmental box gizmo - if you turn that off you can choose your new domelight only. And you're right, you'd exclude all objects in the scene from your tweaked domelight. To make your life easier you should be able to hit the exclude button and in the window that appears choose "include". Using this with nothing included should be the same as excluding all from the scene.

[mhouse777]

....thanks, very helpful.

[seandunderdale]

hdrs from HDRHaven.com should give you the lighting info you need.

[damaggio]

All you need is the hdr you want, a light source and environment fog , then just adjust the settings for your scene scale. No gizmo