Search found 97 matches

by ypoissant
Mon Mar 24, 2014 10:54 pm
Forum: General Development
Topic: Microfacet (RoughGlass) and Multiple Importance Sampling
Replies: 13
Views: 9640

Re: Microfacet (RoughGlass) and Multiple Importance Sampling

One thing I was reluctant to do is generating zero-pdf directions from the equivalent to bsdf->sample() method, because in my mind, it didn't make sense to generate a direction with a zero pdf (if you generate it, then surely its pdf is not zero) and/or simply fail to generate (since the next time ...
by ypoissant
Sun Mar 23, 2014 2:08 pm
Forum: General Development
Topic: Microfacet (RoughGlass) and Multiple Importance Sampling
Replies: 13
Views: 9640

Re: Microfacet (RoughGlass) and Multiple Importance Sampling

Although, maybe not that complicated. My idea is use the microfacet distribution pdf for directions generated and accepted from microfacet generation and use diffuse (for example) pdf for the other rays that were rejected and regenerated from the diffuse distribution. Their respective weights impli...
by ypoissant
Fri Mar 21, 2014 4:12 pm
Forum: General Development
Topic: Microfacet (RoughGlass) and Multiple Importance Sampling
Replies: 13
Views: 9640

Re: Microfacet (RoughGlass) and Multiple Importance Sampling

The way I understand it, if you were to generate a direction with generate() (getting a direction, a bsdf response and a pdf), you should be able to directly call evaluate() (which would give you a 'new' bsdf response and pdf), and I would expect this to have no effect at all (the values returned b...
by ypoissant
Fri Mar 21, 2014 12:31 am
Forum: General Development
Topic: Microfacet (RoughGlass) and Multiple Importance Sampling
Replies: 13
Views: 9640

Re: Microfacet (RoughGlass) and Multiple Importance Sampling

... when I 'generate' a direction for my bsdf, if I 'evaluate' my bxdf for the same direction, I should get identical values for the pdf and the bsdf response, am I right? It depends on the microfacet BRDF model you are implementing. But generally, the pdf and the bsdf are not the same function. Th...
by ypoissant
Fri Mar 07, 2014 11:03 pm
Forum: General Development
Topic: Measure the convergence speed
Replies: 20
Views: 14237

Re: Measure the convergence speed

Thanks for the pointers to those documents. Now on my to-read list.
by ypoissant
Thu Mar 06, 2014 9:57 pm
Forum: General Development
Topic: Measure the convergence speed
Replies: 20
Views: 14237

Re: Measure the convergence speed

The last paper references this one:
http://www.cs.berkeley.edu/~ravir/Overbeck2009AWR.pdf
I think it is a "to read" paper.
by ypoissant
Thu Jan 16, 2014 4:44 pm
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12441

Re: Anybody tried implementing Disney's Principled BRDF?

It is the same idea. The two components, diffuse and specular really refer to the base material and the coating material respectively. In traditional 3D applications, the diffuse and specular are combined together among a set of surface properties. But this just hides the fact that we are really ref...
by ypoissant
Thu Jan 16, 2014 12:08 am
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12441

Re: Anybody tried implementing Disney's Principled BRDF?

And I plotted in the BRDF explorer and found out that GGX is equivalent to TR. Indeed, GGX is a Trowbridge-Reitz BRDF. Schlick BRDF is also a Trowbridge-Reitz BRDF but the shortcuts used in its implementation results in some weird albedos in some parts of the roughness-incidence space. Also I think...
by ypoissant
Wed Jan 15, 2014 11:52 pm
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12441

Re: Anybody tried implementing Disney's Principled BRDF?

Also, I read one of your previous post asking about the implementation of the walter 07 rough refraction brdf. And I found their is a reference implementation in the BRDF explorer. I will post it here as well, hope that helps :) The GGX BRDF implementation as found in BRDF Explorer does not strictl...