What are the new BRDF models for Tweet

[Ilius]

Heyho

I've been wondering what differentiates the new STD BRDF Model from the others and why there is an energy preserving GGX now? Couldnt find an explanation in the Manual, other than the links going to scientific reports which are way too long to read for a quick overview.

In the same regard, i've always wondered why the Ward Model isnt availabe for the Universal Material.

[elsksa]

Hi,

The STD is mentioned here: https://render.otoy.com/forum/viewtopic.php?f=33&t=77996 it will eventually end up in the official documentation, in the future. This could be considered a rule of thumb regarding newly introduced features.

The GGX energy-preserving is self explanatory.
It basically brings a more plausible result with high-roughness materials.
Without it, a loss of energy ("darkening" of the material, even if subtle) will occur. A furnace test will manifest this loss:

The Ward distribution is similar to Beckmann's and is known to behave differently with anisotropy. The developers must have their reasons. Perhaps, due to nonnecessity? The current options should cover most needs.