Search found 96 matches

by ypoissant
Wed May 04, 2016 9:50 pm
Forum: General Development
Topic: How to measure "real" material for rendering
Replies: 11
Views: 5054

Re: How to measure "real" material for rendering

Also, I find a lot of today customers expect spatially varying BRDFs. Especially those customers dealing with textiles materials. SVBRDF produce huge data files though.
by ypoissant
Fri Apr 29, 2016 9:37 pm
Forum: General Development
Topic: How to measure "real" material for rendering
Replies: 11
Views: 5054

Re: How to measure "real" material for rendering

It depends on the accuracy of the measure you want. Start by looking at "Gonioreflectometers". It's only a good start. It can get much more sophisticated than that.
by ypoissant
Thu Jan 07, 2016 9:21 pm
Forum: Data Sets
Topic: Bezier surface models
Replies: 4
Views: 9387

Re: Bezier surface models

If you are interested in nurbs patch models, then you might be interested in looking at Animation:Master. A 3D animation software that models using nurbs patches. You will find the A:M users community here: https://www.hash.com/forums/ . There is a fair number of patch models available. Plus you can...
by ypoissant
Wed Jul 08, 2015 11:35 pm
Forum: General Development
Topic: pbrt-v3 source code now available
Replies: 23
Views: 15947

Re: pbrt-v3 source code now available

On page 214, I don't understand the sentence "When working with these error intervals, it’s important to remember that because (1 ± em) terms represent intervals, canceling them incorrect:" Seems fine to me. Although the numerator and denominator contain the same 'term', they don't cancel...
by ypoissant
Wed Jul 08, 2015 12:25 am
Forum: General Development
Topic: pbrt-v3 source code now available
Replies: 23
Views: 15947

Re: pbrt-v3 source code now available

On page 214, I don't understand the sentence "When working with these error intervals, it’s important to remember that because (1 ± em) terms represent intervals, canceling them incorrect :" On page 219 "then it’s impossible to tell whether it is exactly zero or whether a small positi...
by ypoissant
Tue Jul 07, 2015 5:37 pm
Forum: General Development
Topic: pbrt-v3 source code now available
Replies: 23
Views: 15947

Re: pbrt-v3 source code now available

I'm reading the chapter on floating point precision. I was surprised to read that one can use an "enum" for casting between two different representations. I did not try that but I used to use a "union" for that. Edit: I see that the "union" is later mentioned. So I say ...
by ypoissant
Mon Apr 06, 2015 7:54 pm
Forum: General Development
Topic: cosine lobe sampling PDF
Replies: 11
Views: 9791

Re: cosine lobe sampling PDF

Intuitively When you look at the density of a uniform hemispherical distribution, it looks like a hemisphere. Thus its surface is 2pi. If you look at the density of a cosine distribution, you will observe that it is, itself, a sphere of one unit diameter or 0,5 radius above the surface. Thus its sur...
by ypoissant
Tue Mar 10, 2015 1:37 am
Forum: General Development
Topic: Some images from my renderer
Replies: 8
Views: 4329

Re: Some images from my renderer

My renderer has a layered shading system not too dissimilar from Vray's layered shader or Renderman 19/RIS's LM system. So the chair uses a layered BSDF with a base diffuse BSDF with the color, and then a clearcoat layer on top and then a couple of layers with fingerprints and scratches and stuff, ...
by ypoissant
Tue Mar 10, 2015 1:29 am
Forum: General Development
Topic: Defining roughness
Replies: 6
Views: 3085

Re: Defining roughness

Walter et al paper "Microfacet Models for Refraction through Rough Surfaces" gives equivalency functions for Beckmann roughness, vs Phong exponent but no equivalency for GGX, strangely. Blinn in "Models of Light Reflection for Computer Synthesized Pictures" gives equivalency func...
by ypoissant
Wed Mar 04, 2015 12:26 am
Forum: General Development
Topic: Some images from my renderer
Replies: 8
Views: 4329

Re: Some images from my renderer

Very nice.

How do you handle the lackered material on the chair?

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