Vray Material Hair 3 looking dirty

[evanerichards]

I've been working with the Vray Material Hair 3 shader for a while now. I've got a character with white hair, and for some reason it always ends up looking gray and muddy pretty much all over.

I can blast it with light and it starts to look white the instant before it blows out but pretty much everything else in the scene is blown out by that point.

Does anyone have any tricks and tips for working with the vray hair material?
Please advise.

Thanks!

[georgi.zhekov]

Hello,

Starting with one of the presets for white hair (there are shiny and matted version) you can try and adjust the diffuse color and the transmission to a brighter value.

Thank you,
Georgi Zhekov

[georgi.zhekov]

Also keep in mind that GI has a big impact on the overall look of the hair - for best results you can use brute force and light cache with retrace.

[evanerichards]

Yeah, we're definitely using GI with double brute force.
I think we actually began off the white hair preset but it still seems dark. Hmmmm.

[vlado]

Does anyone have any tricks and tips for working with the vray hair material?

Using secondary bounces (f.e. the light cache) helps; boosting the diffuse component of the material helps as well.

Best regards,
Vlado

[evanerichards]

Does light cache help more than one of the other types of secondary bounce? For instance right now we're using double brute force, but would that be just as good as Light Cache?
I'll take a look at the diffuse component to make sure that's dialed in too.

Thanks Vlado.

[vlado]

Depends on the number of BF bounces; but light cache usually helps better.

Best regards,
Vlado

[evanerichards]

I did some tests and you're right. Using the Light Cache as the secondary renderer DOES make the render look much less muddy. It's as if there was a layer of dirt that was peeled off when you use light cache for secondary bounce. Unfortunately even at a lower sampling setting where there was very visible noise it doubles our render times (which were between 4-8 hours per frame already). So we pretty much won't be able to use it just because of the enormous render hit we'd take.

I played with the diffuse component of the hair shader too but didn't get any difference in my render.

[vlado]

Ok; which V-Ray version are you on? 2.x or 3.x? I've been meaning to add a light boost multiplier anyways, so we might just do that.

Best regards,
Vlado

[evanerichards]

We're on Vray 2.45.01, revision 24039
We'll be upgrading to 3.0 soon I'm sure but we're in the middle of a job right now and can't risk switching things up with our pipeline midway through.

What would the light boost modifier be and how would it work?
Thanks!

[kagemaru]

I have to say i get the same "feeling" as well in max with VrayHairMaterial (that i reckon it's the translation of hair3 in maya).
The shader itself is very nice in several situation, but i myself got a very hard time trying for example to render stuff like white fur and giving it a soft look for example, i even tried layering it with a base shader but with no great results.

[vlado]

What would the light boost modifier be and how would it work?

It would basically give more light to the hair so that you can get somewhat better results even with one light bounce.

Best regards,
Vlado