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Vdb Channels

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Vdb Channels

Unread postby bazuka » Thu Jun 14, 2018 7:02 pm

I did a quick search and i couldnt find any post on this subject, i saw only one related to houdini and vdb,

so my question is, how can i import/load all channels from vdb (fire) for example, with temperature, heat, smoke, velocity, etc... and of course control them? Is there a chance that someone would/could make a quick tutorial on this subject?

Thanks
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Re: Vdb Channels

Unread postby tom_tm » Thu Jun 14, 2018 7:15 pm

Hi,
here are some workflows, but with the raytracer renderer. But it is almost similar with the pathtracer renderer workflow.
Have a look at the extract node.
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Re: Vdb Channels

Unread postby bazuka » Thu Jun 14, 2018 8:01 pm

i saw the extract node, and i understand how it works i was a bit confused with volume node, coz you can only load one vdb channel, also for velocity too, and in my case i have 3 vector info, vel x, vel y, vel z, if you know what i mean...
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Re: Vdb Channels

Unread postby tom_tm » Thu Jun 14, 2018 9:39 pm

First, sorry, I forgot to paste the link above
viewtopic.php?f=5&t=1784&p=6824#p6824

But this may not answer your question.....
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Re: Vdb Channels

Unread postby bazuka » Mon Jun 18, 2018 6:31 am

nope, no sure i understand the workflow, can anyone download the explosion.vdb from vdb website and make a simple scene and of course share with us?

Is there a way to add blackbody shader for volumes?

Thx
bazuka
 
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Re: Vdb Channels

Unread postby mdkai » Mon Jun 18, 2018 8:49 am

Hey
Could you elaborate what specifically you are looking for ?
Most numerical data in clarisse is used as a vector

Pick a channel to work with , apply a volume shader and connect them.
For specific control add a gradient and the adjust the max value of the gradient..usually it stops at 1.0 but you can set it to 200 or 5000 if the data you need to map contains that values range. I think people often forget that detail ;)

Quick tip
Set the gradient to step and just pick a small area of black white to create a sort of band "scanning" through values. This helps also to find cool shapes and add some bright fiery elements..
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Re: Vdb Channels

Unread postby mdkai » Mon Jun 18, 2018 11:45 am

Here is an example file with mapped channel based for density and temperature.

The temperature is mapped as a gradient into a blackbody texture, so gradient points are actual temperature values between 500 ant 16000 Kelvin.
You could also just mapped it in 0-1 gradient and multiply it, or use the scale value in the blackbody ..etc .. many ways :)
vdb.png


VDB used is the explosion file from openvdb.org
http://www.openvdb.org/download/models/ ... on.vdb.zip
Attachments
vdb_test.ple
(49.02 KiB) Downloaded 26 times
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Re: Vdb Channels

Unread postby bruce » Mon Jun 18, 2018 1:53 pm

Hi bazuka,

For the velocity you can use the merge XYZ components in the grid mode dropdown menu!

Cheers.
Bruce
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Technical Artist - Clarisse Specialist
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Re: Vdb Channels

Unread postby bazuka » Mon Jun 18, 2018 9:47 pm

Oh, so many reply's i really appreciate it...
im going to check everything you wrote and post and let you know how did it go ;)

thx
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Re: Vdb Channels

Unread postby bazuka » Tue Jun 19, 2018 10:41 am

here is my solution, i have changed a shader a bit, made it simple :), let me know what you think
Image
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vdb_shd_update.ple
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