VrayEnvironmentFog Problem

[pixela]

When I place a map in the fog density slot, the render becomes full white.
Without any map, I get a nice fog identical all around the image but when I place a noise map in the density, the render becomes 255white.
Tried with different settings but there seems to be a problem.
Is this a known bug?

[Zdravko.Keremidchiev]

What sort of map do you use, a procedural one? Do you use gizmo? Which V-Ray version do you use?
Can you attach an example scene or send it to support@chaosgroup.com

[pixela]

I use a procedural (noise map).
There is a gizmo (but doesn't matter- when gizmo is on or off, I get the same result)


The problem must be scene-dependant. I checked the problem with a simple teapot-plane scene and everything seems to work fine.
So it must be something about the scene.
My scene is extremely heavy, no point trying to simplify as the problem disappears in a simple scene.
I will check if I can simplify repeating the same behaivor.

In the meantime, if you can think of any cause, please let me know.
Thanks.

[Zdravko.Keremidchiev]

Unfortunately I can't think of a reason for such behavior. You can try using another map and check whether the issue still persist. Have you checked whether the texture is correctly mapped?
In any case if you can't manage to find the culprit feel free to contact us and send us the file. We will provide you with our FTP credentials.

[pixela]

Yes I tried using another map, actually the same map is working in the teapot-plane scene.

Luckily I was able to simplify the scene strongly yet we can still see the problem. I am e-mailing the scene.
Looking forward to hear from you.

[Zdravko.Keremidchiev]

Thanks for sending the scene. The issue is due to the usage of high fog emission color value which multiply the fog illumination tremendously.
Make sure that you keep the fog emission color Value very low.

[pixela]

I didnt understand clearly. Do you mean the V value (HSV) of the color?
is this the same issue about using value 255 color with LC?
(I am away from my computer so I will be able to check it tommorrow)

[Zdravko.Keremidchiev]

Yes, that is what I meant the V value (HSV) of the color. I'm not sure which LC issue you have in mind but probably it is a different one.

[pixela]

But in the scene I have sent you the V value for fog emission color is HSV 161,74 97.
I lowered the V value to 11 and even tried Black color but the scene still renders full white when fog color map is active.

Are you sure the issue is about this?
Is this a bug and is there a night build I can have that doesnt have the problem?

[Zdravko.Keremidchiev]

Its actually not a bug and it seems to work fine on our side. I will send you an example scene.

[pixela]

Would you please send me the corrected version of the file I sent to you?

When I make the emission color black, the fog renders totally different and very weak.
(without a map as well).

[Zdravko.Keremidchiev]

It is the corrected version of the file, I only changed the emission color. If you want to increase the EnvironmentFog effect try to decrease the fog distance to 4000 in example.

[pixela]

Thanks.

One more question:
Do we need to set the emission color to black when we use a map?
Is this the default value for emission color?

[Art48]

You have to understand that the emission color simply makes the fog itself act in a way a self-illuminated material would. You make the fog itself create light whereas in reality fog itself are particles in the air that get illuminated by your scene light sources.
I would try to achieve the look you are going for (assuming it should be realistic, and not some kind of artsy stuff) without the emission or only extremely low.