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cumulus clouds

Posted: Wed Mar 30, 2016 6:29 pm
by mwilchrlx
Hey guys,
I wanted to share some of the progress I've had lately rendering cloud formations with maxwell. The density data is very primitive at the moment, so Im only really focusing on the shading model. Im combining several BSDFs to attempt to realistically mimic the complex phase function that real clouds exhibit. Of course, I'm still in the process of stress testing it, but is seems to work for most density, incident ray and camera ray variations.

render times at 2400x1200 are about 1 hour, although the image is 80% clean after about 20 mins.. I just let them cook without really paying attention after that. All data is generated in houdini, assembled in Maya, and rendered in maxwell 3.2. The only "compositing" I'm doing here is a little film grain (which is high at the moment, so sorry), the contact sheet and some very light tonal curves.

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Re: cumulus clouds

Posted: Wed Mar 30, 2016 6:49 pm
by Mihai
Fantastic! Just like the real thing....

Care to write a tutorial for the Maxwell blog?

Re: cumulus clouds

Posted: Wed Mar 30, 2016 6:54 pm
by mwilchrlx
thanks,
Once I'm done with a wider stress test of various types of clouds, I'll definitely put together a tutorial.

Re: cumulus clouds

Posted: Wed Mar 30, 2016 7:07 pm
by Mihai
That would be awesome. Really impressed by these clouds...how cool these would look animated....I would also really like to know how difficult it is to set up the simulation in Houdini and calculation time for these (not for the render I mean).

You're using SSS materials? Strong blue forward scattering? :D

Re: cumulus clouds

Posted: Wed Mar 30, 2016 7:20 pm
by mwilchrlx
thanks a lot!,
The houdini part is a custom set of tools that I use to build clouds specifically. They do animate, but this is specific instance is a static solver and took about 15 mins to set up. The VDB is quite small as well, 10mb on disc (a few million voxels in total). These renders are using instances of a single cloud "snippet". I prefer to assemble in maya, even though there is no VDB preview in viewport (which I would LOVE!). Im also using a single maxwell prim cube to simulate regional atmospheric density shifts (the thicker blue at the bottom of some of the frames). Both the clouds and atmospheric pocket are using a custom material I've made to specifically render clouds. I'm using very little of maxwell's actual scattering attribute. Im trying to follow Beer's law, so it's more about transmission and absorption, although the scattering is indeed very important for the realism.

Re: cumulus clouds

Posted: Wed Mar 30, 2016 7:38 pm
by Mihai
Well I'm all for following Beer's law :mrgreen:

Re: cumulus clouds

Posted: Wed Mar 30, 2016 7:57 pm
by mwilchrlx
cheers to that!!

Re: cumulus clouds

Posted: Thu Mar 31, 2016 8:45 am
by Hervé
Thumbs up.. I did clouds in the past using particles from Realflow, but yours are so cool :)

Re: cumulus clouds

Posted: Thu Mar 31, 2016 1:10 pm
by Rafal SLEK
Nice!

Re: cumulus clouds

Posted: Tue Apr 05, 2016 12:56 am
by seghier
nice renders

Re: cumulus clouds

Posted: Tue Apr 05, 2016 3:58 am
by seghier
if you create image like that
Image

Re: cumulus clouds

Posted: Tue Apr 05, 2016 4:42 pm
by mwilchrlx
I think I'll give that a shot!!... although, I might need to tweak the contrast in post to get such dramatic edges. Here's a few more test scenes.

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Re: cumulus clouds

Posted: Tue Apr 05, 2016 4:57 pm
by lebulb
superbe!

Re: cumulus clouds

Posted: Tue Apr 05, 2016 8:08 pm
by seghier
very nice

Re: cumulus clouds

Posted: Wed Apr 06, 2016 10:51 am
by devista
real :shock: :shock: :shock:
saludos
Luis