Voxel Smoke / Emission

Forums Technical Discussion Voxel Smoke / Emission

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circusmonkey: Member; 2624 posts; Joined: Aug. 2006; Offline

Aug. 18, 2008 6:12 a.m.

When using voxel fluids and “Source from ” where can I find the size of a voxel ( just interested ) as the sidefx example uses the smoke object to obtain this information. Which is of course outside DOPS. would that information be in Dops also

Using the “ source from ” smoke /fire what would be best practice for breaking up the emission of the smoke so its not so uniform ? . Should this done via a volume shader or controlled somehow in the Auto Dop network. After poking around I have not had much luck finding anything

R

Edited by - Aug. 20, 2008 01:48:13

Gone fishing


Allegro: Member; 696 posts; Joined: March 2006; Offline

Aug. 18, 2008 10:10 a.m.

Video 5 covers this, and I'm pretty sure one of the earlier ones mentions it too.

http://www.sidefx.com/index.php?option=com_content&task=view&id=1301&Itemid=132 [sidefx.com]

The more radical your noise, the more varied your source will be.

Stephen Tucker
VFXTD


circusmonkey: Member; 2624 posts; Joined: Aug. 2006; Offline

Aug. 18, 2008 9:44 p.m.

I had a look at that , it covers “ smoke from object ” not “ source from object ” The trees that get created are totally different , so I am a bit confused where I am supoosed to look for the data I need to add the effects I want

r

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Allegro: Member; 696 posts; Joined: March 2006; Offline

Aug. 18, 2008 10:36 p.m.

You can source from object, but still do an isooffset in the geometry level (the same as what gets dropped down when you do smoke from object) By Sourcing from a volume primitive instead of a polygonal one, you can add noise into it (with the volume mix node) which can be randomized volumetrically.

Stephen Tucker
VFXTD


circusmonkey: Member; 2624 posts; Joined: Aug. 2006; Offline

Aug. 19, 2008 2:08 a.m.

Hi Stephen ,
Thanks so much for the pointer , its hard sometimes to know if I should be pumping data into Dops or adjusting it as it comes back out. I have created a simple test scene for others.

Shows Voxel smoke using noise to control the emission , when using “source from object ” .

Attachments:
FluidNoiseSourceFrom.hip (461.5 KB)

Gone fishing


Allegro: Member; 696 posts; Joined: March 2006; Offline

Aug. 19, 2008 10:09 a.m.

You got the right idea. Two more things you can do though is to add Time based noise to your volume mixes, and then tell your static object (emitter) to read deforming geometry.

I also added a small bit of vortex confinement on the solver.

Attachments:
fluidnoisesourcefrom.hip (463.3 KB)

Stephen Tucker
VFXTD


circusmonkey: Member; 2624 posts; Joined: Aug. 2006; Offline

Aug. 20, 2008 1:55 a.m.

Hey Stephen ,
you beat me to it ! Ive done a sample scene to create a growing mist / fog type effect. It uses noise over time. Really like fluids in Houdini !

Theres a QT of a 100frame render plus scene file

Attachments:
VoxelSmokeNoiseOverTime.hip (789.5 KB)
VoxleSmokeNoise.mov (162.4 KB)
NoiseEmission.jpg (31.8 KB)

Gone fishing


Allegro: Member; 696 posts; Joined: March 2006; Offline

Aug. 20, 2008 8:29 a.m.

Nice

Look forward to seeing what you come up with as you learn more

Stephen Tucker
VFXTD


IndyZoneCo: Member; 77 posts; Joined: Nov. 2007; Offline

Aug. 27, 2008 12:15 a.m.

I've been trying to do an atmospheric volume fog like this with a spotlight shining through the fog that shows its cone. Shining a spotlight through the an isooffset volume does not produce the cone.

Theoretically, the atmosphere cone should show up as the light gets picked up by each volume substep. (or so I've been told.) What else is missing? Hip file is attached (modified from circusmonkey's setup). Can anyone take a look at it?

Attachments:
VolumeLightCone179.hip (1.0 MB)


IndyZoneCo: Member; 77 posts; Joined: Nov. 2007; Offline

Sept. 2, 2008 11:41 p.m.

Anyone? I'm actually trying to get the atmopheric spotlight effect with a big fog volume box–a technique that Mark showed off that the Sig 2008 Mantra Master Class.


circusmonkey: Member; 2624 posts; Joined: Aug. 2006; Offline

Sept. 3, 2008 7:54 a.m.

Anyone? I'm actually trying to get the atmopheric spotlight effect with a big fog volume box–a technique that Mark showed off that the Sig 2008 Mantra Master Class

Unfortunately Ive not done what your trying to do ? how about get in touch with support for a scene file maybe ?

rob

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Allegro: Member; 696 posts; Joined: March 2006; Offline

Sept. 3, 2008 12:23 p.m.

It should be just a matter of shining a light through your fog volume… The cone should be visible through the fog.

Stephen Tucker
VFXTD


circusmonkey: Member; 2624 posts; Joined: Aug. 2006; Offline

Sept. 15, 2008 5:40 a.m.

oppps

post not needed

ops:

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ykcosmo: Member; 288 posts; Joined: July 2005; Offline

Sept. 16, 2008 10:43 a.m.

here is my latest voxel rendering….-.-!

Attachments:
storm0131.jpg (282.4 KB)

^_^


stevenong: Member; 1631 posts; Joined: July 2005; Offline

Sept. 16, 2008 12:37 p.m.

That looks great ykcosmo! So, when are we gonna see the animation?

Please keep the updates coming!

Cheers!
steven


circusmonkey: Member; 2624 posts; Joined: Aug. 2006; Offline

Sept. 16, 2008 5:05 p.m.

ykcosmo , great stuff . Just how are you handling writing the sim data out ? Just using the file DOP and hitting play is so slow. I have tried using a ROP Then tried reading the data back in , but get errors in the Dop import nodes

Gone fishing


jason_iversen: Member; 12490 posts; Joined: July 2005; Online

Sept. 16, 2008 5:54 p.m.

Just a note: there is a new “Timeless” option on the File DOP that might help ease that pain.

The Journal on Tuesday, September 2, 2008
Houdini 9.5.217: DOP Networks have a new Timeless option which allows them to cook without concern for history. This allows networks that merely read in a baked .sim sequence, for example, to load only the current frame rather than all the frames up to the current frame.

Jason Iversen, Technology Supervisor & FX Pipeline/R+D Lead @ Weta FX
also, http://www.odforce.net [www.odforce.net]


ykcosmo: Member; 288 posts; Joined: July 2005; Offline

Sept. 16, 2008 11:41 p.m.

I wrote the $F4.bgeo onto my hardisk……………then use file sop read in..

^_^


circusmonkey: Member; 2624 posts; Joined: Aug. 2006; Offline

Sept. 17, 2008 6:52 a.m.

Just a note: there is a new “Timeless” option on the File DOP that might help ease that pain.

Wheres that ?

Rob

Gone fishing


tamte: Member; 8594 posts; Joined: July 2007; Offline

Sept. 17, 2008 7:33 a.m.

DOP Network/Simulation Tab

Tomas Slancik
FX Supervisor
Method Studios, NY

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