Search found 97 matches

by ypoissant
Wed Jan 15, 2014 11:34 pm
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12441

Re: Anybody tried implementing Disney's Principled BRDF?

You could select 50/50 between the coating or the base BRDF for reflection using a Russian Roulette. Or you could use a Russian Roulette on the coating microfacet Fresnel reflectance. Both are good. Personally, I select based on the coating Fresnel reflectance.
by ypoissant
Mon Jan 13, 2014 5:08 pm
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12441

Re: Anybody tried implementing Disney's Principled BRDF?

1. I guessed that the 2 specular lobes are two seperate brdf weighted by Fresnel. But in each of the brdf, there are already a Fresnel term in the microfacet model. How exactly are they combined? Whatever energy is not reflected by the coating BRDF goes through to the base BRDF. Since the energy re...
by ypoissant
Mon Jan 13, 2014 3:15 am
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12441

Re: Anybody tried implementing Disney's Principled BRDF?

Their principled BRDF is based on Walter et al. "Microfacet Models for Refraction through Rough Surfaces" GGX BRDF. I'd recommend reading this article. You can find an implementation of the GGX BRDF in Disney's "BRDF Explorer": an open source application for exploring the characteristics of BRDFs. D...
by ypoissant
Wed Nov 27, 2013 9:13 pm
Forum: Links & Papers
Topic: Implementing Vertex Connection and Merging (tech report)
Replies: 12
Views: 17272

Re: Implementing Vertex Connection and Merging (tech report)

Oups! Sorry. I missed it. Thanks.
by ypoissant
Wed Nov 27, 2013 5:16 pm
Forum: Links & Papers
Topic: Implementing Vertex Connection and Merging (tech report)
Replies: 12
Views: 17272

Re: Implementing Vertex Connection and Merging (tech report)

Have the slides or course notes been posted somewhere yet?
by ypoissant
Tue Nov 26, 2013 10:58 pm
Forum: General Development
Topic: Frame buffer for spectral rendering
Replies: 8
Views: 6518

Re: Frame buffer for spectral rendering

It is easy to linearize sRGB by de-gammaing it. The color pipeline I use is: 1- degamma all colors (textures and colors specified as RGB from the user) when they are read from file or from input fields. 2- Do all rendering calculation using those linearized RGB colors. 3- Accumulate those RGB result...
by ypoissant
Tue Nov 26, 2013 8:12 pm
Forum: General Development
Topic: Heckbert ray grammar and today BRDF
Replies: 2
Views: 3706

Re: Heckbert ray grammar and today BRDF

Ah Thanks Deitger. I still haven't read Wenzel papers and thesis on Manifold Exploration. I just put those on my to-read next list.
by ypoissant
Tue Nov 26, 2013 3:42 pm
Forum: General Development
Topic: Heckbert ray grammar and today BRDF
Replies: 2
Views: 3706

Heckbert ray grammar and today BRDF

I'm wondering how do you classify a ray that originates from a smooth BRDF? A BRDF that is smooth but is not perfect Mirror? The original Heckbert paper "Adaptive Rasiosity Textures for Bidirectional Ray Tracing" was published in 1990 and the 'S' classification was specifically for perfect Mirror. S...
by ypoissant
Wed Nov 20, 2013 3:40 pm
Forum: General Development
Topic: Working Color Spaces
Replies: 11
Views: 10652

Re: Working Color Spaces

What I meant was: IF we can only afford 3 numbers (due to storage or computational constraints), why not just go for the most straightforward representation, "Splitted Equispace RGB" in your terminology? And according to your experiments it IS a good one. What sets it apart from the others is that ...
by ypoissant
Wed Nov 20, 2013 3:07 am
Forum: General Development
Topic: Working Color Spaces
Replies: 11
Views: 10652

Re: Working Color Spaces

Here are the filters and the methods in graphic form:
Color Sapces Gaussian.jpg
All Gaussian filters
Color Sapces Gaussian.jpg (96.98 KiB) Viewed 7924 times
Spectrum to Bands.jpg
Stectrum to bands filtering methods
Spectrum to Bands.jpg (76.18 KiB) Viewed 7924 times