Search found 16 matches

by tuomlarsen
Thu Jun 27, 2013 12:55 pm
Forum: My First...
Topic: Low-discrepancy samplers
Replies: 17
Views: 15937

Re: Low-discrepancy samplers

Notice that I can't use it in my renderer due to patents... This is quite surprising to me - what patents? How were they allowed to patent it? I presume that e.g. Halton sequence was invented by a guy named Halton (and not, say Nvidia?). Perhaps the patent was issued because they were the first to ...
by tuomlarsen
Wed Jun 26, 2013 6:17 pm
Forum: My First...
Topic: Low-discrepancy samplers
Replies: 17
Views: 15937

Re: Low-discrepancy samplers

Thanks to everyone for the insightful replies, it's very kind of you. It finally starts to make a bit more sense to me!
by tuomlarsen
Mon Jun 24, 2013 4:46 pm
Forum: My First...
Topic: Low-discrepancy samplers
Replies: 17
Views: 15937

Re: Low-discrepancy samplers

Thank you, friedlinguini! That tiny-bit clears things up - but what about, say, stratified sampling? What corresponds to sampling dimension in stratified sampling? I mean, with Halton/Sobol one uses ever higher primes with every light bounce - but in case of stratified sampling..what do the stratas ...
by tuomlarsen
Mon Jun 24, 2013 11:34 am
Forum: My First...
Topic: Low-discrepancy samplers
Replies: 17
Views: 15937

Re: Low-discrepancy samplers

In other words, I more or less "get" that it is somehow possible to generate sequence of numbers which are nicely apart of each other. The problem I have, even if I generate such numbers and visually verify that they do approximately what I want (by generating many points on a plane), I st...
by tuomlarsen
Mon Jun 24, 2013 11:28 am
Forum: My First...
Topic: Low-discrepancy samplers
Replies: 17
Views: 15937

Re: Low-discrepancy samplers

Jacco, thanks many times for the code you posted! But I must be really stupid because even that you posted step-by-step instructions I cannot make it work. 1) Instantiate a SobolGenerator (e.g., SobolGenerator sobol; ); Ok, easy. 2) For each path call 'sobol.Generate( frameNumber ); smallpt uses sev...
by tuomlarsen
Sun Jun 23, 2013 9:12 pm
Forum: My First...
Topic: Low-discrepancy samplers
Replies: 17
Views: 15937

Low-discrepancy samplers

Hello, I'm trying to understand how low discrepancy sequences. I think I got the basic idea but I have really difficulty to make it work inside a renderer. Please, can someone explain a few things to me? 1. Should I replace all random() functions with the one of low discrepancy or is it enough to re...
by tuomlarsen
Wed Nov 28, 2012 11:52 am
Forum: My First...
Topic: Ward tone mapping
Replies: 8
Views: 6086

Re: Ward tone mapping

I think I have the equation 4 from Reinhard's paper working, thanks for the pointer. But I'm still wondering - Luxrender, Sfera, probably Indigo as well, all use a slightly different method originally written for "Violet" tone-mapper by Nick Chapman. I tried to contact him, so far without ...
by tuomlarsen
Mon Nov 26, 2012 8:18 pm
Forum: My First...
Topic: Ward tone mapping
Replies: 8
Views: 6086

Re: Ward tone mapping

Thanks for the suggestion! Unfortunately, I have the same problem with the algorithm by Reinhard - each of the implementation I saw is very different. This seems to be very close to the paper: https://github.com/krisher/Path-Tracer/blob/master/src/main/java/edu/rit/krisher/raytracer/image/ImageUtil....
by tuomlarsen
Sun Nov 25, 2012 6:28 pm
Forum: My First...
Topic: Ward tone mapping
Replies: 8
Views: 6086

Ward tone mapping

Hello, I'm trying to implement a tone mapping operator and as I was searching for a simple algorithm I found "A Contrast-Based Scalefactor for Luminance Display" by Greg Ward published in Graphic Gems IV. The main idea is that the scale factor equals to: Lda = Ldmax / 2 sf = (1 / Ldmax) * ...
by tuomlarsen
Tue Nov 13, 2012 9:41 pm
Forum: My First...
Topic: Solid angle of triangle
Replies: 5
Views: 5219

Re: Solid angle of triangle

dr_eck, thank you very much! I now see where the simpler method breaks. And stupid me, 1e6 is not tiny at all... beason, thanks for the posted code, I found the whole file interesting, especially the part where you choose between approximate and accurate sampling. Also, I (and I'm sure many others) ...

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