(Stochastic) Progressive Photon Mapping

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Re: (Stochastic) Progressive Photon Mapping

Postby B.Y.O.B. » Sun Sep 13, 2015 3:03 am

VCM is implemented in LuxCore I think.
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Re: (Stochastic) Progressive Photon Mapping

Postby SATtva » Sun Sep 13, 2015 6:51 am

But currently only on the CPU. About porting it over to the GPU, i think only Dade can comment.
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Re: (Stochastic) Progressive Photon Mapping

Postby spectral fusion » Tue Sep 15, 2015 8:27 am

SATtva wrote:But currently only on the CPU. About porting it over to the GPU, i think only Dade can comment.

Well having gpu accelerated vcm would be a dream come true if possible, of course first thing would be to fix the sampling errors, but as intense as vcm is to calculate maybe it would be alot more efficient on gpu?

Fun fact: pixar renderman's vcm is both slower and less accurate compared to luxrenders and ours is marked experimental alpha, plus it is missing the initial start radius and alpha tightening, i was quite disappointed by that to be honest so even with our shortcomings we ended up ahead of the big renderman.

When it comes to sppm i still wonder if it could be used to drive better vcm sampling just imagine if we could use it to only sample the parts of the image that really needs more samples using vcm instead of this slow brute force method.

Also interesting though only for afaik Hierarchical Automatic Stopping Condition for Monte Carlo Global Illumination aka adapting sampling for bdpt: http://jo.dreggn.org/home/2009_stopping.pdf
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Re: (Stochastic) Progressive Photon Mapping

Postby psor » Thu Oct 22, 2015 11:46 am

@Dade --> SPPM bug (splotches)

Something is fishy within the Luxrender (classic) SPPM integration. It seems to
be a very small bug tho. And it seems to be in all versions including 1.5, 1.5.1
and 1.6.

I was looking at the Cubo scene again and boom I've got splotches (a) over the
specular surface after about 200spp. SPPM settings didn't matter the choice of
sampler neither. The picture turned always to something I thought I could not
work with. I've been mistaken tho. Non the less it took a bit until it came to
my mind to reload (b) the FLM again. :mrgreen: :mrgreen: :mrgreen:

I'm not sure what happend (c) and havent had the time to reproduce but it
truly looks weird and interesting at the same time. It was the same procedure.
Reload the FLM file from just another test render. Surprise, surprise ...

BUG_WinOSi.CUBO.Scene.BLENDER_LuxRender_101-LCL-SPPM-MLT-PSOR.jpg

Thanks for watching! ;o))

edit: Added info about versions.


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Re: (Stochastic) Progressive Photon Mapping

Postby Dade » Thu Oct 22, 2015 11:56 am

psor wrote:@Dade --> SPPM bug (splotches)


Psor, thanks but SPPM has been surpassed by BiDir+VM and I don't sincerely have the time to look into the code of old Lux: at the moment, all the focus is on new LuxCore code for v2.x. If someone else want, be guest :mrgreen:
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Re: (Stochastic) Progressive Photon Mapping

Postby psor » Thu Oct 22, 2015 12:03 pm

That's fine with me Dade. So what about dispersion then? ;P

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Re: (Stochastic) Progressive Photon Mapping

Postby Meelis » Thu Oct 22, 2015 1:15 pm

The SPPM FLM resume has never worked properly.
Only way is to blend rendered samples together in some image editor.
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Re: (Stochastic) Progressive Photon Mapping

Postby SATtva » Thu Oct 22, 2015 2:29 pm

psor wrote:That's fine with me Dade. So what about dispersion then? ;P

It's in the works: viewtopic.php?f=8&t=12454
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