Author Topic: Roughness  (Read 5447 times)

2016-01-05, 20:30:50

hugojackson18

  • Active Users
  • **
  • Posts: 36
    • View Profile
Hey Haggi, I was wondering what roughness type coronaSurface is using at the moment. Is it GGX? Does it have a curve like the 3dsmax version? I'd like some clarification on this =)

2016-01-06, 10:55:13
Reply #1

haggi

  • Moderator
  • Active Users
  • ***
  • Posts: 338
    • View Profile
Sorry, I have no idea which roughness model the Corona surface is based on. What curve do you mean? I have no 3dsmax with corona here. Is this a curve based on facing ratio like fresnel?

2016-01-06, 11:24:49
Reply #2

SairesArt

  • Active Users
  • **
  • Posts: 687
  • Pizza | The Cheesen One
    • View Profile
    • SairesArt Portfolio
Hey Haggi, I was wondering what roughness type coronaSurface is using at the moment. Is it GGX? Does it have a curve like the 3dsmax version? I'd like some clarification on this =)
Might wanna read the post from a Corona dev here:
https://corona-renderer.com/forum/index.php/topic,8989.msg58369.html#msg58369

The way GGX is implemented differs from others due to visual compatibility with older brdf models.

2016-01-06, 21:31:21
Reply #3

hugojackson18

  • Active Users
  • **
  • Posts: 36
    • View Profile
SairesArt Yes I read that. That's why I'm asking this.

Basically, nearly everyone is using GGX BRDF nowadays for roughness. Corona uses it too but they put a curve on the roughness remapping the values to look more like the previous BRDF model (which i think goes against the whole point of switching to a new BRDF model).
So at the moment, you can't get 100% rough materials in Corona 3dsmax. Ondra said this will be rectified soon but I was wondering what you had done with the Corona surface implementation and how it worked.

Also, I've got a question about the Fresnel and the Fresnel map input. What is the use for the Fresnel map? I can't seem to understand how it works. I'd expect it to be a F0 input but it doesn't seem to be. And does the Fresnel input understand 1/IOR when values are under 1, like vray does?