Search found 12 matches

by b_old
Thu Oct 01, 2020 7:35 am
Forum: General Development
Topic: “Importance Sampling of Many Lights” - paper: participating media
Replies: 2
Views: 787

Re: “Importance Sampling of Many Lights” - paper: participating media

Thanks for your explanation, I think I understand the section better now! I had also started a conversation on [computer graphics stack exchange, which might be helpful: https://computergraphics.stackexchange.com/questions/10269/importance-sampling-of-many-lights-with-adaptive-tree-splitting-paper-p...
by b_old
Tue Sep 29, 2020 6:37 am
Forum: General Development
Topic: “Importance Sampling of Many Lights” - paper: participating media
Replies: 2
Views: 787

“Importance Sampling of Many Lights” - paper: participating media

I'm reading and implementing a paper about Importance Sampling of Many Lights with Adaptive Tree Splitting. http://aconty.com/pdf/many-lights-hpg2018.pdf In section 5.2 on cluster importance for participating media, there is a part that I don't understand: How do they compute the vectors o1, o2? I d...
by b_old
Tue Jul 16, 2019 6:44 am
Forum: General Development
Topic: Light-tracer weights
Replies: 9
Views: 2998

Re: Light-tracer weights

I spent a little more time on this, but mainly fixing tangential issues, like e.g. normalizing the reconstruction filter. To wrap this up, what seems to work for me is using 2.0 * A (A = virtual image plane) in the formulas I posted originally. I cannot explain the factor of 2, but I tested a couple...
by b_old
Fri Jul 12, 2019 8:40 am
Forum: General Development
Topic: Light-tracer weights
Replies: 9
Views: 2998

Re: Light-tracer weights

I don’t mean the naive pathtracer implementation by “division by PDF to generate the first intersection point”. Do your path tracing implementation (both with and without NEE) take the “PDF to generate the first intersection point” into account? That PDF is a PDF to generate a primary ray from a ca...
by b_old
Thu Jul 11, 2019 8:56 am
Forum: General Development
Topic: Light-tracer weights
Replies: 9
Views: 2998

Re: Light-tracer weights

I think it depends on the ground truth implementation. What is your expected brightness? Is it the result of path tracing? If so, does it contain the division by PDF to generate the first intersection point (the second vertex if the first is on lens)? Ground truth in this case are my other integrat...
by b_old
Thu Jul 11, 2019 8:30 am
Forum: General Development
Topic: Light-tracer weights
Replies: 9
Views: 2998

Re: Light-tracer weights

Does “connect to the camera” mean that you are trying to do NEE with light tracing? If so, I have feeling that your weight calculation contains many factors that shouldn’t be there. e.g. image plane area at z = 1, and too many cosine factors. Weight calculation contains only lens area and perhaps m...
by b_old
Tue Jul 09, 2019 8:29 am
Forum: General Development
Topic: Light-tracer weights
Replies: 9
Views: 2998

Light-tracer weights

I'm currently trying to implement a basic light-tracer. The resulting images don't have the expected brightness, however. I strongly suspect it is related to sample weights, when I connect to the camera. For now I only consider a pin hole camera with a lens radius of zero. I apply the following weig...
by b_old
Fri Jul 13, 2018 8:10 pm
Forum: General Development
Topic: Decomposition tracking question
Replies: 0
Views: 4855

Decomposition tracking question

I have a working implementation of spectral tracking as described in this paper and am trying to combine it with decomposition tracking, also described in that paper. I decided to implement the simplest version first, ignoring weights and spectral data. The source code of my attempt can be found in ...
by b_old
Fri Mar 23, 2018 11:02 am
Forum: General Development
Topic: Spectral tracking question
Replies: 6
Views: 5967

Re: Spectral tracking question

Isn't this implemented in PBRT? Hm, I quickly started implementing this for absorption only material and the results where even more noisy than spectral tracking (with history and no emission), which discourages me from going further in that direction. Instead of this pdf you could probably mix the...
by b_old
Mon Mar 19, 2018 10:53 am
Forum: General Development
Topic: Spectral tracking question
Replies: 6
Views: 5967

Re: Spectral tracking question

I actually wonder how you get your reference image so clear with jut 16 spp. In this case I used closed-form tracking as described in the volume rendering course . (I think this is valid even for spectrally refined media, as long as there is no scattering. More on that below.) Try the weighting sch...