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emit smoke color from a texture


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#1 R_cyph

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Posted 03 May 2013 - 08:52 AM

Hey,

I've searched the forums/ houdini help docs and i'm having trouble finding anything on emitting smoke color from a textured plane. I found an example of what I mean. Any help would be greatly appreciated!

View on Vimeo.



#2 bloomendale

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Posted 03 May 2013 - 11:49 AM

If you have plane with uvs, scatter bunch of points, inherit uvs, apply color through colormap vop/ texture vop to the points. Create vector volume from these points using fluid source sop. Then import this volume as vector field in your smoke object and don't forget to advect it every step (using gas field advect dop or adding your field to same node inside solver).
Then import it back in sops and render (some shaders automatically use Cd volume as color so name it accordingly) with other fields.

#3 azman

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Posted 04 May 2013 - 07:57 AM

hi,
it's very good explanation but could you make a hip for us to study this.

thanks for advance

#4 melazoma

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Posted 04 May 2013 - 08:53 PM

Give this file a try. This should shows the basic idea to add color (Cd.x/Cd.y/Cd.z) to your smoke sim and advect it.

edit: re-uploaded hipnc file.

Attached Files


Edited by melazoma, 04 May 2013 - 08:58 PM.


#5 R_cyph

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Posted 05 May 2013 - 07:56 PM

I downloaded your file and everything makes sense. But, for some reason the shader isn't picking up the Cd its just using the billowsmoke color :P

#6 ryew

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Posted 06 May 2013 - 08:33 PM

Nice trick, melazoma - thanks for sharing.

R_cyph - cache the sim to disk with the ROP provided, and make sure the render flag is on the file read node, you should see it render as displayed

#7 melazoma

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Posted 06 May 2013 - 10:41 PM

Hi ryew, thanks for helping out. I should have cleaned the file before uploading.
Given enough hardware power, I'd like to take a stab at something a little more elaborate, but my 3 years old MacBook Air was enough for this little exercise.

#8 llldemonlll

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Posted 07 May 2013 - 06:16 AM

Recemtly saw this FumeFX test too and made the same in Houdini. But in my case, after my smoke sim was done I made a source with point color match texture I want, and go with advection particles by vel field in POPs(we can do the simple advection setup in DOPs). After when you have your points you just bring them to a smoke shader using Point Cloud Open + Point Cloud Filter by Cd attribute and simply add to your smoke color. Got the same effect like you.
One thing which I want to spot, that important thing to do this like post sim otherwise this advection during the main sim make the sim time slow down and you get more control for playing with color. And using Point Clouds gives you control under filtering(bluring) your color, so you can control in shader - do you want more soft or more sharpness color. Also sharpness dependd on how many points you advected. I tryed both way, both way are good but personally I prefered the way with Point Clouds.

#9 dark_cry

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Posted 21 May 2013 - 10:28 AM

Give this file a try. This should shows the basic idea to add color (Cd.x/Cd.y/Cd.z) to your smoke sim and advect it.

edit: re-uploaded hipnc file.


If you advect Cd for certain amount of frames, the color will be very rough, so the good way is to add gas blur and blur the cd with small radius. I've just added this gas blur to your sim. You can compare. :)

Attached Files



#10 jasonj3d

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Posted 29 May 2013 - 01:55 PM

If you look at the first smoke sim in the video that R_cyph posted, the density is being emitted for multiple frames and always emits with the texture's colors. In this hip file that has been posted, it looks like the color field is just an additional field that is put into the sim on the first frame and then advected with the velocity.

How would you go about actually having the density sourced with the texture's colors? or have the color field at least be emitted for multiple frames to match something that emits more than just one frame?

thanks!

#11 melazoma

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Posted 31 May 2013 - 07:06 AM

bloomendale showed the way to source color from multiple frames here:
http://forums.odforc...ms/#entry107545

In addition to this, I also put in dark_cry's suggestion to gas blur the Cd fields.
The latest result is here and the hip file attached. Cache the sim in import_pyro_fields and render.

http://vimeo.com/67401392

Attached Files



#12 sliver

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Posted 31 May 2013 - 07:22 AM

Great work!

http://www.adrienrollet.com
vimeo.com/adrienrollet





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