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Simple moving fireball with Maya Fluids
Posted: Apr 16, 2007 - 04:39 PM
Category: example scenes
Here is a simple file with a moving emitter in a fluid. The detail depends on the fluid resolution in this case and no texturing was used. I created the file in a few minutes starting with a default 3d fluid and emitter. The emitter was parented to an animated sphere, and thus gets the motion of the sphere. The emitter settings are otherwise at the defaults.

The fluid node was setup as follows:
1. Make the transparency very low( but not zero or the render will look chunky).
2. Enable self shadows but turn off real lights to speed up rendering.
3. Make density buoyancy zero.
4. Make the temperature method = "Dynamic Grid"
5. Increase the temperature turbulence and buoyancy, as well as the temperature scale. Also add some temperature dissipation.. the exact amount is critical for a good look.
6. Set "High Detail Solve" to "All grids". This and perhaps a little velocity->swirl helps to get more detail in the smoke.
7. Set "Render Interpolator" to "Smooth"
8. Make the fluid a tight fit for the desired path of the smoke. To do this shape the fluid using the size X,Y,Z attribute, then adjust the resolution so it is in proportion to these size values. So if sizeX is 2 times sizeY then resolutionX should also be 2 times resolutionY.
9. Due to the tight fit I set all the fluid boundaries to "none". This way the smoke is not trapped in a tight box and air can flow in and out of the fluid grid.
10. Simulate at a moderate resolution to preview, then increase to the desired resolution before rendering( always making sure to keep the resolution proportional to the size values ).
11. I slightly adjusted the opacity input bias and also moved the first gradient indice very slightly to the right to threshold the bottom end of the density, although this is not that important. You can also adjust the incandescence ramp and bias value to improve the look. I made the color ramp grey instead of white to look more like smoke than steam. If you instead want it all the way to black then turn off self shadowing as it will have no effect( this will speed up rendering ). Another way to speed rendering might be to lower the fluid shading quality, although if too low you will see dithering artifacts(dots). The fluid is also blurry so one could perhaps even get away without any antialiasing in the render settings.

I didn't bother caching but simply rendered, allowing the render to also run the simulation. It took about 50 sec a frame on my machine( most of that time was rendering ). However if you are going to render on a farm then you should first cache the simulation... only the temperature and density grids need to be cache in this example.
In order to post any comments, you must be logged in!
  Posted by amorgan  on  25 Apr, 2007  at  09:08 AM

Amazing work.

  Posted by Duncan Brinsmead  on  17 Apr, 2007  at  02:09 AM

That site is still active, but you may have needed a silver membership to access it. I need to figure out how to download all those posts, so I can create a compiled listing for this site.
http://forums.alias.com/webx?14@@.3baec116

  Posted by gustavo.s  on  16 Apr, 2007  at  03:46 PM

Hi Duncan,

Amazing work. As usual.
I was wandering if there was still a link to the post in your old blog, where you have tons of fluids posts.

Regards

gus.

 
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