Questions about GGX shader support ..

[Anonymous]

Do you plan to support GGX shaders on "TRUELIGHT" materials in VRED?

Hi. I am studying VRED rendering.

I have tested it several times and expect all materials of "TRUELIGHT" to be based on the PHONG shader.

I would like to support the GGX shader for a realistic metallic look.

Unfortunately, currently VRED supports GGX shaders only in "X-Rite" and "OCS".
 
Why does VRED not support GGX shader by default?

Do you have plans for future support?

I look forward to your reply. Thank you.

[michael_nikelsky · Accepted solution]

Our shaders use a slightly modified Ashikhmin-Shirley model, not a phong model. GGX did not exist when we developed our materials, it is a fairly new model. Sadly it is quite difficult to switch to a new BRDF Model without changing the look of the scene and that is an absolute Nogo for our customers. 

However, there is an undocumented and unsupported(!!!) option to switch to GGX for the plastic material by changing the BRDFType to 2 in the Node Editor. This does not change the IBL in OpenGL and Precomputed modes but only the evaluation of lightsources and when using Full  global illumination mode. 

But as I said, this is unusupported and we might change the behaviour at any time in the future and some features might not even be supported correctly, so I would not recommend to use it in any sort of production environment. 

Kind regards

Michael

[richardlevene]

---

and that is an absolute Nogo for our customers.

---

NOT US!!!! 😉

But yes I know we are not your typical customer.

Materials/material editor is definitely something high on our list that we would love to see improvements in. Well anything that involve actual visual quality/detail and rendering to make fully photoreal images. Raytracing

Very interesting regarding the brdf model option on the plastic material Michael! So when you say it has to be in Full GI mode, would creating a plastic material, setting its brdf model to 2 and then creating an override in the material to compute Full GI do the trick for it to render correctly or does the full scene need to be computed with Full GI set?

Best,

Richard

[michael_nikelsky]

Hi Richard,

using overrides should be fine, the issue is just the precomputed ibl is an approximation of the environment based on a blinn-phong model which will not be changed when using GGX. The GGX requires sampling or explicit lightsources to be evaluated correctly. It doesn´t matter what other materials in the scenes are using.

If GGX is important for you please let us know, we already had some discussing about exposing the brdf type in the material UI.

Regarding other material improvements: As you might have heard already we are working on supporting substance materials, so this should give you a lot more flexibility.

Kind regards

Michael

[richardlevene]

Hi Michael,

We use GGX for everything pretty much when we render with Vray.

I mean keeping up with all the latest rendering improvements in the industry is something we find very important and expect developers of renderers to be on top of and implement. Currently we feel that in this regard Vred does lack this. Obviously Vred's interactivity is far superior to other renderers that have to go through DCC applications but to get truely photorealistic imagery, you have more power and control with other renderers. I am talking strictly in Raytracing. Maybe you are doing well with VR and all that collaboration stuff, although Unreal and Unity are getting a lot of automotive clients, but on the raytracing side we would like to see things get more advance and current in Vred.

Materials and the material editor are still really basic. Yes this is nice just for the general user who is picking up the program for the first time but given how much the application costs, the pro version should really have a material editor worthy of a PRO program.

Even looking at Keyshot, that has come on leaps and bounds and what you can actually render there is impressive and they really developed the power of their material editor. They have a simple material list like Vred but then if you want power you can go deeper into the material node editor and create more complex materials. I mean it is leaps and bounds beyond Vred's current one in terms of what you can create.

Vred could be truely untouchable if it supported a few more things in the raytracing renderer.

Best,

Richard