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Thick smoke using Particles

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Jack Napier
Thick smoke using Particles
on Nov 21, 2007 at 5:47:11 am

Hi,

I have been rather unsuccessful in creating thick voluminous smoke (with self shadowing) using the Particle Cloud shader. Pretty much like a volcano (or even the fluid examples).

I found the shader works best for a more thin and whispy smoke. The thick smoke using the shader only looks good in long shots; not medium or close-ups.

I am trying to avoid using fluids due the simulation and redering times.

Any help, links to tutorials or prior posts will be deeply appreciated.

Thanks.

-Jack


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Jill Calhoun
Re: Thick smoke using Particles
on Nov 21, 2007 at 7:23:23 am

Try using sprites. Use the pen tool in photoshop to create a roundish shape. Convert the path to a selection. Feather the selection by about ten. Export as a .targa with an alpha (one of the drop down menus from the main menu will allow you to save your selection as an Alpha. Do this before exporting as a targa 32 bit).

Back in Maya, create an emitter with sprites. Create a lambert and use your .targa in the color node. Place your new lambert on the sprites. Add a General dynamic attribute --> sprite scale ppx ppy. Create a ramp to use on both ppx and ppy.Black is small. White is large. The faster it gets white, the faster your "smoke" will get bigger/more billowy.

In the opacity PP attribute, create a new ramp. White is solid. Black is see thru.

Add a dynamic attribute --> twist pp. Set your white value higher than 1. The number is equivalent to degrees, so try 180.Add a small amount of noise.

Add gravity and an airfield.

Change the different attributes as necessary until it looks how you want it.

You can also create a series of shapes (name them 1-10 or so) to export as targas to create an image sequence (so all the particles are even less uniform). If you do this, in the file attribute tab of your lambert (I think) there should be a box to check that says Image Sequence. Check this for a sequence.

Not sure how familiar you are with particles.
Hope this helps!


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Jack Napier
Re: Thick smoke using Particles
on Nov 27, 2007 at 8:38:20 am

Thanks for your suggestion Jill.

I have not worked a great deal with sprites but I get the idea. My only concern is that each sprite will cast a shadow so I might not get a "3D" feel if the camera is also panning around the smoke. But will give it a shot and let you know if I was successful.

Thanks again.

-J


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Jill Calhoun
Re: Thick smoke using Particles
on Dec 1, 2007 at 4:30:16 pm

If the shadow looks square, which it may or may not (Not sure if it will shadow the alpha or the sprite, or if the shadow will even show up at all with sprites- I don't remember getting true shadows from the hardware renderer) you can:

a. render the shadow as a separate pass and tweek with blur in a compositing program (with the shadow on it's own layer).

b. As a separate pass, turn the particle type from sprite to cloudy surface and render a shadow pass from that. The particles will be in the same spot and as cloudy surface will render accurately. Turn off the primary visibility for the particles so that you only get the shadows they cast.

You may have already figured something out, though. But thought I'd respond just in case.

Good Luck!
Jill


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Jen-Shuo Liang
Re: Thick smoke using Particles
on Mar 2, 2011 at 2:41:46 pm

I used photoshop and its filter cloud to make the image, and saved it to the targa files with alpha channel.

However, when I am in maya, the color of the smoke using sprite and this sequence looks farely square.

Does anyone have any ideas?


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kim jong hyo
Re: Thick smoke using Particles
on Sep 12, 2008 at 5:47:29 am

very thx



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