When should GGX be used?

V-Ray V-Ray for 3ds Max General
1

Hello,

I have been reading around the fourms last night and I have seen a few posts that are suggesting people are opting to use GGX as a default BDRF type for ALL Shaders / Materials?

Can I get peoples opinions on this? Should you be using GGX for all Materials, Glass, Plastic, Metal? And if so is there a chart made yet for the tail fall off for these materials?

Sorry if I am behind the 8 ball but there is so much information to take in regarding this!

If anyone can share there thought it would be very helpful.

Thanks.

2

In case you haven’t seen this… https://labs.chaosgroup.com/index.php/rendering-rd/improvements-to-the-gtr-brdf/

3

Brilliant - I have not seen this, thanks for sharing.

I actually am a Maya V-Ray user, does anyone know if 3.1 for Maya has been released?

Also now with 3.1 is it correct to assume you should now be using GGX as default for all shaders?

4

I guess you can use it for everything; the reason that it’s not the default is that it is not too well tested yet. If we decide that it works without problems, we will probably make it the default BRDF.

Best regards,
Vlado

5

Use for everything and set higher value 3-5 on the tail falloff to get similar to Blinn and Ward. It always looks better though.

6

Brilliant, Thanks for the info!

7

Would be cool to get a chart in the Vray help with some real world values for some settings as a way to create mental connections between values. Cloth, etc.

8

https://labs.chaosgroup.com/wp-content/uploads/2015/02/ggx\_old\_gamma.png

I think this chart is very good for matching real world objects glossiness… I did some cloth yesterday with about glossiness at 0.24 and ggx tail at 3.5 - I can post the exact setting when I get to work.

9

It’s a great graph, what I mean is a list next to it that says things like (as you’ve posted) a certain cloth is .24 / 3.5

I guess anyone can just make their own but time savers are great.

10

I just saw this - https://labs.chaosgroup.com/index.php/rendering-rd/improvements-to-the-gtr-brdf/

Which refers to it needing a fix that’ll be in the next service pack. is this out/have an eta? We were about to update but if there’s another fix incoming we’ll hold off.

11

The next service pack will probably come out sometime in May.

Best regards,
Vlado

12

That’s the one that will work with Max 2016?

13

Yes; although technically even the current build will work in Max 2016 (they are binary compatible). However there are some new features in Max 2016 that we added support for in the new SP.

Best regards,
Vlado