Vraylight Material porblem

[Arch.Hany]

very simple scene just for clarification

source light and 2 boxes plus vrayenvironment fog

1st image a vraylight plane with texture and affect diffuse : 70 ( to get that fog effect without increasing the multiplier too much because it overburns the texture )

2nd image trying to get same effect using vray light material using same texture ( direct illumination on )

since their is no affect diffuse option in the vray light material i cant get similar result
when i increase the light material multiplier too much the texture overburns

is their a way to achieve this using vray light material ?

[Arch.Hany]

anyone can help please ?

[vlado]

Do you think you can post that scene? I'm not exactly sure how you have set up things. Is there a specific reason you have to use a VRayLightMtl material instead of a VRayLight?

Best regards,
Vlado

[Arch.Hany]

I prefer using it mainly for showing texture in viewport to see what am doing
also vray lights has limitation in terms of shape
vray light material is so much flexible i could add it and map it anywhere on any kind of complex model or even part of it
blend it with other textures/ materials etc

here is the file
hope you can help me out
thanks in advance

[hermit.crab]

There isn't a way to achieve the effect with the VRayLightMtl since it does not have that type of control as VRayLights. If shape is something of importance - use VRayMeshLights.

[anthonyh]

You could use VrayLightMtl as the visible box and put your Vray Light in front of it set to `invisible` to create the fog so you can control each value in case of burnout ?

[Arch.Hany]

hermit.crab thats really unfortunate

anthonyh that is a solution for simple cases i think
but a complex case where texture is animated along complex model would be impossible

[^Lele^]

The VRayAtmosphere RE and the SelfIllumination RE should help you achieve what you want in post, without much trouble.
You may need to create a few multi-matte REs to mask out the specific parts of a complex multi-material with lightselects on intricate geo, but if not the two layers will get you most of the way.
Unless i have misunderstood you.

[Arch.Hany]

^Lele^ multiple problems here
that would be very hard to test before rendering final and i think would produce enormous noise that almost cant be fixed due to lack of information in dark pixels

Also if by any chance the fog is reflected/refracted on a surface that would be very hard to fix in post and will look very unrealistic

[Arch.Hany]

As a side note i tried increasing the generate gi value in the object's vray properties but that didnt affect the fog in any way which i didn't understand why

Isn't it supposed to affect it ?

[^Lele^]

Ok, so the setup is as follows:
VrayLightMtl with texture, set intensity as it's pleasing to the eye (let's say, 1.0).
That lightMtl becomes the child of a MtlWrapper, for which you set the GI generation multiplier to whatever works for the fog (say, 30).
Assign the mtlWrapper to the multi-sub slot, or the node you want to turn into a light, not the lightMtl.
Tick "scatter GI" in the environmentFog.

[Arch.Hany]

^Lele^ thanks alot man never though of that
That solved the problem perfectly

[Arch.Hany]

^Lele^ i can confirm this workaround doesn't work with vray next gpu

[^Lele^]

^Lele^ i can confirm this workaround doesn't work with vray next gpu

Mh, pity.
Could you write to support, ideally with a tiny sample scene set up attached (so it's quicker for them to find the issue.)?