Search found 97 matches

by ypoissant
Wed Mar 04, 2015 12:26 am
Forum: General Development
Topic: Some images from my renderer
Replies: 8
Views: 7264

Re: Some images from my renderer

Very nice.

How do you handle the lackered material on the chair?
by ypoissant
Tue Jan 13, 2015 12:49 am
Forum: General Development
Topic: cosine lobe sampling PDF
Replies: 11
Views: 15269

Re: cosine lobe sampling PDF

Thank's for the link, I plan to implement some microfacet BRDFs as well as a next step. I thought of Phong as about quite simple model to implement for test purposes. But surprisingly it is not so simple. However, I don't understand what you mean by "You don't have to guess/hack about sampling dire...
by ypoissant
Fri Jan 09, 2015 12:43 am
Forum: General Development
Topic: cosine lobe sampling PDF
Replies: 11
Views: 15269

Re: cosine lobe sampling PDF

Why not use a more plausible and modern BRDF such as GGX ? http://www.cs.cornell.edu/~srm/publications/egsr07-btdf.pdf You don't have to guess/hack about sampling directions and pdf with this BRDF. Sorry, it's been so long when I used Phong for sampling that I would not know how to directly answer y...
by ypoissant
Tue Dec 02, 2014 3:13 pm
Forum: General Development
Topic: Questions about layered bsdfs.
Replies: 2
Views: 3351

Re: Questions about layered bsdfs.

I just found this recent article. I haven't had time to read it yet but given the authors, it should be interesting.
"A Comprehensive Framework for Rendering Layered Materials", by Jakob, D'Eon, Jakob, Marschner, 2014.
by ypoissant
Tue Nov 25, 2014 1:15 am
Forum: General Development
Topic: Questions about layered bsdfs.
Replies: 2
Views: 3351

Re: Questions about layered bsdfs.

More readings for layered BSDF: "A Simple Layered RGB BRDF Model", by Granier and Heidrich, 2003. "Arbitrarily Layered Micro-Facet Surfaces", by Weidlich and Wilkie, 2007. "Exploring the Potential of Layered BRDF Models", by Weidlich and Wilkie, 2009. "Thinking in Layers - Modelling with Layered Sur...
by ypoissant
Wed Oct 01, 2014 6:00 pm
Forum: General Development
Topic: Experimental Development Framework (C++ and ray tracing)
Replies: 12
Views: 10920

Re: Experimental Development Framework (C++ and ray tracing)

cgribble wrote:Not surprisingly, I like rtVTK: http://www.rtvtk.org
That looks cool. I'll take a look at this. Thanks.
by ypoissant
Sat Aug 09, 2014 2:57 am
Forum: General Development
Topic: Color space: when to multiply by the matrix
Replies: 13
Views: 9187

Re: Color space: when to multiply by the matrix

I'd choose "the majority wins" tactic in this situation. If most of your colors/textures input are in a color space A and you are handed one plate in color space B. then I would convert B to A, do the calculations in A.
by ypoissant
Wed Jun 25, 2014 6:54 pm
Forum: General Development
Topic: When do Fresnel Equations Apply/Fresnel BRDFs
Replies: 8
Views: 5609

Re: When do Fresnel Equations Apply/Fresnel BRDFs

I never attempted quadrature methods on BRDF normal distribution functions. I already have a set of Monte-Carlo functions for testing different properties of BRDFs in a BRDF unit testing file. Those functions output Excel spreadsheets. For me, it is easier to just add another one so I tend to think ...
by ypoissant
Wed Jun 25, 2014 10:59 am
Forum: General Development
Topic: When do Fresnel Equations Apply/Fresnel BRDFs
Replies: 8
Views: 5609

Re: When do Fresnel Equations Apply/Fresnel BRDFs

The Fresnel factor has to be multiplied by the proportion of properly oriented microfacet surfaces within a differential area. And this function is not available AFAIK (although it is computable using Monte-Carlo techniques) Isn't that given by the pdf associated with the microfacet distribution ? ...
by ypoissant
Tue Jun 24, 2014 11:41 pm
Forum: General Development
Topic: When do Fresnel Equations Apply/Fresnel BRDFs
Replies: 8
Views: 5609

Re: When do Fresnel Equations Apply/Fresnel BRDFs

However, for purely-diffuse surfaces, the results are also generally bad. Paper, wood, and various paints, for example, tend to have very low specular, yet this cannot be accounted for by the refractive index alone (since it is not large enough). Wikipedia states that the equations assume the inter...