Volumetrics

[David Bluecame]

Thank you, Steve!

Will you please confirm that this Beta3 is working correctly in your volumetric tests and also that it's not causing new issues in other scenes?

Best regards. David.

[David Bluecame]

Hello,

I've been investigating this further and my previous solution was incomplete and did not solve all the issues with Volumes.

For example, when rendering a volume over a transparent background (for compositing purposes) the area of the volume and boundary box had still an Alpha=1 which did not allow for compositing.

So, I have cancelled my previous Pull Request and created a new Pull Request with different changes:

https://github.com/YafaRay/Core/pull/73

This time I focused on trying to fix the Alpha calculation, trying to get a more correct Alpha values for all the volume pixels. Apparently this has fixed the problems with Alpha > 1.0 so I could remove the check I used in my previous fix.

Some examples (you can download all files from https://github.com/DavidBluecame/YafaRay---unofficial-Builds/raw/master/YafaRay%20volumetrics%20fix%20-%20example%20files.zip )

Rendering over other objects:

Before this fix, incorrect:


After this fix, apparently correct:



Rendering over opaque background:

Before this fix, incorrect:


After this fix, apparently correct:



Rendering over transparent background (this is the problem that was not fixed with my previous fix and it's hopefully solved now):

Before this fix, incorrect:


After this fix, apparently correct:



Example of composition made in GIMP with a background image and the new (correct) volume generated with transparent background:


Maybe it's not yet a perfect solution (in the composition I can still see that the edge of the volume is not 100% transparent, but I still believe it's working much better than before. To make it perfect I would need help from the experts and senior developers as I don't yet understand well the internals of the renderer.

In any case, I hope you find this useful. However, as it's a big change in a main component of YafaRay, please test it thoroughly with your scenes to make sure it does not cause any new issues.

[EDIT] I just made a Beta4 for Blender 2.74 in Windows 7 / 8.1 64 bits and these Volumetric fixes applied, so I've edited this post to include the link as well:
https://github.com/DavidBluecame/YafaRay---unofficial-Builds/raw/master/YafaRay%20v0.1.5%20-%20Beta%204%20(2015-04-04)%20unofficial%20build%20for%20Blender%202.74%20Windows%207-8.1%2064bit.zip

Best regards. David.

[David Bluecame]

Hello,

I've made an experimental build for Blender 2.74 / Windows 7/8.1 64bits including this fix. Please see:

http://www.yafaray.org/community/forum/ ... 038#p31038

The new build also includes another change from povmaniaco to fix volumetrics when using the SPPM integrator.

Please test it and let us know if it works for you.

[David Bluecame]

Hello,

I've made experimental version builds of YafaRay for Linux 32 and 64bit:

http://www.yafaray.org/community/forum/viewtopic.php?p=31050#p31050

I hope you find them interesting.