Search found 175 matches

by jbikker
Wed Jul 19, 2017 10:46 am
Forum: General Development
Topic: MIS with IBL
Replies: 14
Views: 3195

Re: MIS with IBL

rtpt wrote:if you want to combine ris/mis have a look at the work of j. talbot and refs.


I am aware of his work, but I don't think he solved this issue, and in fact, I don't think it's possible.
by jbikker
Tue Jul 18, 2017 1:59 pm
Forum: General Development
Topic: MIS with IBL
Replies: 14
Views: 3195

Re: MIS with IBL

Out of curiosity, because it sounds like I'm doing something very similar and back when I was investigating it I saw no bias issues, what is the RIS trap? Is RIS conceptually flawed or is it a reoccurring 'gotcha' that you keep forgetting? I used RIS for my light sources in the past: out of e.g. 1k...
by jbikker
Fri Jul 14, 2017 1:31 pm
Forum: General Development
Topic: MIS with IBL
Replies: 14
Views: 3195

Re: MIS with IBL

You can easily test whether this indeed is the problem by using a light selection probability that is only a function of deterministically known things at the shading point (i.e. every time you land at this point you will compute the exact same light selection probability). That is indeed correct: ...
by jbikker
Tue Jul 11, 2017 2:45 pm
Forum: General Development
Topic: MIS with IBL
Replies: 14
Views: 3195

Re: MIS with IBL

Just to be sure, the sample you're taking to calculate the probabilities is being discarded right after that and not being reused? Correct. Out of curiosity, how do you notice that there's bias? Well the setup is a simple box with a single-sided quad light well below the ceiling. One side of the bo...
by jbikker
Mon Jul 10, 2017 6:23 pm
Forum: General Development
Topic: MIS with IBL
Replies: 14
Views: 3195

Re: MIS with IBL

Thanks for your replies. When your ray stumble upon a light source and you want to do MIS, you need to know the probability of it being selected. It's impossible to know if that probability without having sampled random points on all other light sources in your sampling method. I'm not sure if doing...
by jbikker
Thu Jul 06, 2017 10:51 am
Forum: General Development
Topic: MIS with IBL
Replies: 14
Views: 3195

MIS with IBL

Hi all, I have a question about something that I can't seem to wrap my head around. Here's the situation: In a unidirectional path tracer with next event estimation and MIS lights can be reached by a random bounce and by explicitly sampling the light source. For MIS I thus take both pdfs into consid...
by jbikker
Thu Jun 15, 2017 12:26 pm
Forum: Visuals
Topic: My First Spectral rendering
Replies: 5
Views: 1776

Re: My First Spectral rendering

I hadn't seen it, but it looks good.
On a related note: https://www.shadertoy.com/view/lssfD7 , Lambert reflection without tangents.
by jbikker
Thu Jun 15, 2017 7:21 am
Forum: Visuals
Topic: My First Spectral rendering
Replies: 5
Views: 1776

Re: My First Spectral rendering

Quartz. I'm tracing four wavelengths as proposed by the Hero paper, but I have not implemented their MIS scheme yet. In this case it's useless by the way; the quartz will reduce weights for all wavelengths but the hero to zero anyway. For the floor and walls the four wavelengths are very effective, ...
by jbikker
Fri Jun 09, 2017 10:19 am
Forum: Visuals
Topic: My First Spectral rendering
Replies: 5
Views: 1776

My First Spectral rendering

Been playing with spectral rendering: spectraldragon.jpg Completely new world for me so be gentle. :) This is with tracing four wavelengths at once; three of them are killed when a wavelength dependent pure specular dielectric is encountered. The tracer accumulates CIE XYZ colors and converts them t...
by jbikker
Wed May 17, 2017 2:40 pm
Forum: Visuals
Topic: Glitch Pictures anyone?
Replies: 75
Views: 79260

Re: Glitch Pictures anyone?

Correct. :)

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