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Volumetrics

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Volumetrics

Post Tue Jun 10, 2014 4:02 pm

Hello,

I thought I would try Volumetrics, but I am having some difficulty. I read/followed the instructions in the user guide, but which ever type of "volume region" or texture for "Noise Volume" I use, I always get the same result, which is uniform.(I was mainly attempting a "Noise volume")

I am currently on win7-64
Yafaray 1.5 stable
Blender 2.7a -64

Could someone be so kind as to post a blender file with "Noise volume" that I could look at?
Stem
 
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Joined: Wed Aug 03, 2011 2:19 am

Re: Volumetrics

Post Wed Nov 05, 2014 2:23 am

Hello everyone,

I'm just trying to get used to yafaray (which is really a great renderer), but I got some problems with volumetrics.
Is there somewhere an example file, which shows how to use volumetrics?
I have read the manual, and I tried to download the sample files from here: http://static.yafaray.org/testscenes/yaftests.zip, but they are not available any more.

I hope someone can help me.

Thank you
Christian
LemyD
 
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Re: Volumetrics

Post Thu Nov 06, 2014 4:54 pm

Hi, sorry I just saw this thread now. The files I used to make the images on the documentation page were from an old version of blender (pre-2.50), and so I took a few minutes to make some of them work in the latest blender version.

Well, the files render now, but there are artifacts appearing inside the volume regions, like this:

render.png
render.png (260.36 KiB) Viewed 15282 times


This happens with new files I test with too, and I'm not sure what is going on. If it is just a simple issue with a scene setting or something easy to fix in the exporter that I can find then I'll report back here, but for now it seems volumetric rendering has issues.

Anyway, I'll post the updated example files in case anyone finds them useful:
volumetric_examples.zip
(594.55 KiB) Downloaded 372 times
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wizofboz
 
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Re: Volumetrics

Post Thu Nov 06, 2014 11:43 pm

It's been broken for some time. Possibly since Blender 2.66:-
http://www.yafaray.org/community/forum/ ... =13&t=4957

Possibly it's related to this; though I'm not sure:-
http://www.yafaray.org/node/563
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stoneage
 
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Re: Volumetrics

Post Fri Nov 07, 2014 3:27 pm

@Wizofboz: Thank you for the example files. I will try them.
@Stoneage: Thank you for the information. Will try to do some more tests, and maybe, those tests help you guys to fix this.

But anyway Thanks for the answers!

Christian
LemyD
 
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Re: Volumetrics

Post Mon Mar 30, 2015 9:11 am

wizofboz wrote:Anyway, I'll post the updated example files in case anyone finds them useful:


Thank you very much for posting those.
Stem
 
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Re: Volumetrics

Post Mon Mar 30, 2015 9:20 am

stoneage wrote:It's been broken for some time. Possibly since Blender 2.66:-
http://www.yafaray.org/community/forum/ ... =13&t=4957


Thank you for the link.

I now have Blender 2.62(r44136) installed. I downloaded a build of Yafaray (6712_yafaray-package-windows64bit) and volumes are now rendering OK.

I am not sure if I am using the best combination (blender+yafaray) for volumetrics. The yafaray build I have is shown in blender as 0.1.2.alpha. Was there a final 0.1.2?
Stem
 
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Joined: Wed Aug 03, 2011 2:19 am

Re: Volumetrics

Post Mon Mar 30, 2015 10:16 am

Hi Stem

Could you try with latest versions of YafaRay from here:
http://www.yafaray.org/community/forum/ ... m.php?f=12
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Samo
 
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Re: Volumetrics

Post Mon Mar 30, 2015 6:17 pm

I can see still happens with the latest version. I will take a look at this issue as soon as I can.
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David Bluecame
 
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Re: Volumetrics

Post Mon Mar 30, 2015 7:17 pm

Hi Samo,

Samo wrote:Could you try with latest versions of YafaRay from here:
http://www.yafaray.org/community/forum/ ... m.php?f=12


I did try that version, but unfortunatly, still a problem with volumes.
Stem
 
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Joined: Wed Aug 03, 2011 2:19 am

Re: Volumetrics

Post Mon Mar 30, 2015 7:22 pm

David Bluecame wrote:I can see still happens with the latest version. I will take a look at this issue as soon as I can.


Thank you very much.
Stem
 
Posts: 19
Joined: Wed Aug 03, 2011 2:19 am

Re: Volumetrics

Post Tue Mar 31, 2015 7:56 pm

Hello,

I think I have identified the problem with the Volumetrics artifacts.

If you click in the artifacts and look at the Alpha channel value, you will see Alpha is bigger than 1.0!! I believe Alpha should always be between 0.0 (transparent) and 1.0 (opaque).

In my tests, I added a line in the file integrator.cc to make sure that alpha never goes over 1.0 in volumetrics:

// col = T * L_o + L_v
colorA_t col = integrate(rstate, c_ray); // L_o
col *= scene->volIntegrator->transmittance(rstate, c_ray); // T
col += scene->volIntegrator->integrate(rstate, c_ray); // L_v
if(col.A>1.f) col.A=1.f; //FIXME: From the previous operations alpha could be more than 1.0 (why??) causing artifacts, so I've set this upper limit to avoid them.
imageFilm->addSample(wt * col, j, i, dx, dy, &a);

if(do_depth)
{
float depth = 0.f;

After this change, I recompiled and the volume was (apparently) correctly generated without artifacts:

Image

I will try to prepare new builds with this fix in place over the next days. I will also send a pull request to fix the source, although we should investigate the root cause of why the Alpha values is going above 1.0 in the first place.
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David Bluecame
 
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Re: Volumetrics

Post Tue Mar 31, 2015 8:10 pm

I've made a couple more tests and looks ok with the change.

I've sent the pull request: https://github.com/YafaRay/Core/pull/72

Still I have pending to prepare new Windows builds with this change. I will try to do it over the next days.
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David Bluecame
 
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Re: Volumetrics

Post Thu Apr 02, 2015 4:12 am

Hello,

I've made a new 64bit build with the fix for the Volumetrics artifacts, tested with Blender 2.74 with Windows 8.1 and Windows 7.

Please try it and let me know if it fixes the Volumetrics artifacts and also please make sure this change does not cause any other unexpected problems.

https://github.com/DavidBluecame/YafaRay---unofficial-Builds/raw/master/YafaRay%20v0.1.5%20-%20Beta%203%20(2015-04-02)%20unofficial%20build%20for%20Blender%202.74%20Windows%207-8.1%2064bit.zip

I hope it helps. Best regards!
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David Bluecame
 
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Re: Volumetrics

Post Thu Apr 02, 2015 11:51 am

David Bluecame wrote:I've made a new 64bit build with the fix for the Volumetrics artifacts, tested with Blender 2.74 with Windows 8.1 and Windows 7.


Thank you very much for taking the time to find and fix this problem.

Best Regards,

-Steve
Stem
 
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