View Full Version : Dust particles in air, need expert help!

10 October 2006, 11:24 AM
Hi. I'm working on an animation and need a solution for this problem:

I have a scene that is a dark, almost black room with a lot of visible dust in the air.

1. First all you see is dust particles lit by a bright light from above.

2. A heavy iron ball hanging from a rope falls down, starts stirring up particles.

3. The rope stops the ball. The dust moves with the air and starts circling movements, as you will see if you move your hand in the dust under a lamp.

4. The air calms down and the dust slows down to very slow floating movement.

I am done animating the ball and rope, using keyframes not dynamics.
What i need help with is how to create and influence the particles. I'm not sure how to render them either, what would you use to get the feeling of subtle but very visible dust particles lit from above?

I made a GIF animation do demonstrate what I'm looking for:

This might seem like a detail that can easily be faked, but it's very important that the dust looks just the way I want it in this scene, and that it looks very realistic.

Note the arrows i have drawn showing the particle movement.

I have used Maya for years, just never got around to particles. I'm extremely grateful for any help! :scream:

10 October 2006, 04:12 PM
don't have time to go into too much detail, but you could try some of the following:

1) parent air fields to the ball and offset them slightly using a bit of attenuation
2) use a drag field to get the particles to slow down after they are outside of the air fields sphere of influence.
3) you can also use collisions between the particles and the ball and rope. (particles >> make collide)
4) You could use a volume emitter in the form of a large cube to fill your scene with particles - play with direction and velocity to get a subtle gravitational fake.
5) use a gentle turbulence field without attenuation to break up the linearity of the sim
6) you will probably use spheres or points (possibly sprites) to do the particles. sprites could be the easiest option as you could paint them in photoshop and just reference the image. (sprite is an instance of a bmp). If you use points, you'll probably need some post blurring and fx since they are hardware rendered. Spheres could work but you will have to play with the particle shader (default particleCloud) and it can take quite a bit to get the right look. For dut you would look at noise, density, falloff etc.

good luck,

10 October 2006, 04:44 PM
Another method: You can use fluid containers as fields for particle systems!

-Create a low-res 3d fluid container to fill the area you need movement in.
-Make sure velocity is set to dynamic. You may want to turn on velocity draw so you can see what the fluid is doing.
-Create a locator, and make it a motion field to the fluid container and animate it as your gif shows. You should see your velocity arrows shifting around in reaction to the motion field.
-Now in the dynamic relationship editor, assign the fluid container as a field to the particles.

The time consuming part of this will be trying to get truly swirly particles. I find 2d fluid containers swirl around more than 3d ones. You will also need to set your fluid buoyancy to 0, adjust the swirl attribute, and play with the motion field settings until you get something you like. It will take some tweaking, but imo this is exactly how I would tackle this one.

10 October 2006, 09:36 PM
Thanks a lot both of you! I will try both methods tomorrow. This is why I love CGTalk, thanks again! :thumbsup:

02 February 2007, 04:37 PM
If you did make test shots (or have still images)

would you mind posting your particle set up or a sample animation ? I'm looking to do the exact same effect (dust being shuffled)

CGTalk Moderation
02 February 2007, 04:37 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.