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Mesh lighting for raytraced ambient occlusion, anyone?

Posted: Fri Sep 13, 2013 8:40 am
by fxrex
Ever since the introduction of the render view for Blender Internal, I've been getting such GREAT results with a few good lights and raytraced ambient occlusion that it's just KILLING me that indirect (or mesh) lighting is only available for the approximate gather method for AO. The mesh lighting in Approximate AO is awesome, don't get me wrong, it's great for neon glow and indirect light passes and I've been able to light some lovely looking scenes using mesh lights alone just by cranking up the power, but you need accurate shadows for realism.
Cycles, the obvious alternative is still much too slow for animations of all but the simplest scenes. A last resort would be to get a workstation with a current CUDA card, but that would also mean a faster processor and faster render view and BI render which for all I know might only just make BI a stronger contender to Cycles.
I understand there used to be something called the "Render Branch" which had indirect lighting for raytraced gather. I fear it has been killed off for some reason, but I just need to know if it's alive or if there's anything similar in the works.
Any other info that could help would be greatly appreciated.


Posted: Fri Oct 04, 2013 8:02 am
by sgraham
I ran into the same concern with Indirect not being available for raytracing. I find the Approximate stuff to be very innacurate - though fast. I think the accuracy can be improved, but I feel like in order to debug it, you really need the raytraced version for comparison.

So I went ahead and downloaded the Blender source and added my own raytraced Indirect Illum. Once I get the code tightened up and a few more fixes ready to go, I will see about patching it back to the main repository so it should hopefully be in a version to come shortly.

I started a post about it here:

Posted: Fri Oct 04, 2013 8:04 am
by sgraham
Also, forgot to mention... I tried the old Render branch version you are talking about, it is still available. Sorry I don't have a link off hand, but really there's not much of a point, because when I tried it it seemed very broken. Pretty sure it was suffering from the same reversed normal among other problems that I talk about in the post mentioned earlier.

Posted: Mon Oct 07, 2013 10:08 am
by fxrex
Thanks a whole lot for this, sgraham. Now I'm excited. You have exactly what I'm looking for. Your raytraced indirect lighting results are great. I really wish I could be of some help, except maybe as a tester. Do you have a working windows build by any chance?

Posted: Mon Oct 07, 2013 5:59 pm
by sgraham
I have a windows build, but it doesn't have all the features possible to Blender. I think it has all the core stuff and is only missing OpenMP and motion tracking.

I'd be happy to share it with you. I need to change a few more minor things before I have a stable build. ETA sometime today.


Posted: Mon Oct 07, 2013 6:42 pm
by fxrex
Thanks a whole lot, man. That would be great.

Posted: Wed Oct 09, 2013 12:05 am
by sgraham
Sorry, took longer than expected to clean things up.

Here's the link to the custom build.

There is also a test scene in there if you don't want to set up a scene.

Please let me know if you encounter anything weird and show tests if you have time! That will help when getting changes into the main branch of code.

Posted: Wed Oct 09, 2013 7:16 pm
by fxrex
Thanks a million, Shaun. It's everything I expected it to be and so far it appears to be just as stable as the trunk build which is what I usually use.[/img]

Posted: Wed Oct 09, 2013 7:48 pm
by fxrex

Posted: Wed Oct 09, 2013 7:57 pm
by fxrex
Here's the same scene with Indirect Lighting turned off. (I had AO(Mult) and Environment lighting both set to 0.5 and Emit values for the emission materials varied between 3 and 5.)

Posted: Tue Oct 15, 2013 2:17 am
by fxrex
Here's the scene rendered with Approximate AO. There's the usual problem of innacurate and missing shadows. It's not exactly awful though, and it rendered in 1min53secs at HD 720 as opposed to the first image which rendered in 32min2secs (the raytraced version needed 15 samples to eliminate the noise. Image

Posted: Tue Oct 15, 2013 4:02 am
by fxrex
An actual example of indirect lighting (raytraced).

Posted: Tue Oct 15, 2013 7:28 am
by sgraham
Oh wow! I totally missed these tests as I've been more focused on the artist forums and didn't get an email on this one. Nice tests!

That last one looks like it has a lot of color bounce, is it emitting color, or do you have the factor turned way up?

There's been a bunch of discussion about this patch on the artist forum as well, I plan on focusing on the artist forum simply because the forum is easier to use and seems more active.

Here's a link to the post: ... lease-Test!

(dont forget the '!' at the end, looks like this forum cuts it off in the link)

Posted: Tue Oct 15, 2013 8:52 am
by fxrex
In the last test the factor was left at 1 and there was no emit on any of the materials. The textures all had fully saturated colours, though and I guess the colour bleeding would be less exaggerated if 1 had used 2 bounces instead of one. Thankfully the factor could also be reduced if desired. I'll render a 2 bounce version and also check out the blender artist thread. Great work, man!