PDA

View Full Version : Create Animated Dust?


mswertfager
08-20-2004, 04:16 PM
I am trying to animate dust falling through Light Fog. I tried an approach recommended from an online Genome tutorial "I also wanted the appearance of dust particles floating in the air, so I mapped the second spotlight fog's density attribute with a 3D granite texture. By animating the granite's placement node moving through the scene, I can get the dust to travel. " http://www.thegnomonworkshop.com/tutorials/decay_regions/decay_regions.html

I tried this approach with a variety of speeds for the y transform movement of the granite texture in the density attribute. While the effect worked great for still shots. If the speed is enough to cause visible transform motion, the foating dust particles just start to blink, rather than moving down. Any suggestions?

-Michael
mswertfager@yahoo.com

Zac256
08-20-2004, 05:34 PM
You're probably going to want to approach this dynamically using particles and sprites.

-Zac

mswertfager
08-20-2004, 09:41 PM
Ya. I have considered particles as an option and ran a couple of test scenes. However, if this method can work it would be so much more flexible as I don't have to deal with multipasses for every shot and there are about 10 shots which I need the dust for.

But if I can't get this method to work as it is suggested by the Genome tutorial I will abandon it for particles.

-Michael

Richard Slechta
08-24-2004, 12:06 AM
There is an alternate to particles. You could put a speck-ally granite texture on the color and transparency of a Lambert. Map that to a couple of cylinders one inside the other. animate the cylinders in opposing directions and position in the lightfog beam. play with the angle or shapes

For more control you could map the granite to incandescence instead of color and render the granite, lightfog and scene in different passes. When composting throw the lightfog layer as an alpha to the granit cylinders so only the grains in the lightfog will be visible.

Hope this makes a little sense. BTW, I believe the genome is Gnomon, pronounces like the little elf with a Jamaican accent.
cheers

BillSpradlin
08-24-2004, 08:07 AM
Yea, it's pronounced Know-mon if I'm not mistaken.

mattswilson
08-24-2004, 03:55 PM
I have had to do quite a bit of this recently, for the film I am working on. I have found that I am the happiest with rendering a moderately large number of cloud particles, at a very small radius in a pass with only your volume casting light(the volume parameter off in this pass), and perhaps an ambient filler. It really easy to drop this over your scene in a comp and you have lots of control over the final look. You can play with the shader to make it shimmer and sparkle, so it works pretty well. I have never like that texture method, plus this way you can have objects collect dust and use dynamics.

mswertfager
08-24-2004, 06:53 PM
Two good suggestions Richard and Matt. I'll try both to see what effect works best for this project.

Hey Matt, I tried going to your website as listed in your public porfolio and the URL looks broken. I would like to check out your stuff, do you have another address?
-Michael

sundialsvc4
08-24-2004, 08:04 PM
For all kinds of fog-and-dust effects of this nature, definitely use compositing. It doesn't make sense at all to do it in the render.

A sense of "dustiness" can be achieved with a translucent plane that is simply passing in front of the camera lens. Several such planes moving at different speeds and directions, all out of focus, give a simple way to get the desired sense of "a volume of obscuring dust." Just fill the entire camera-frame with the stuff and you have plenty of raw material for comping.

In addition to these layers, which achieve the sense of obscuring and of volume, put in some layers of moving dust .. created using particle systems. These will be the spice; the visual details, more clearly in-focus, which help to convey the sense of motion and direction. Often there is some object in the foreground of the shot against which this detail effect is supposed to be viewed, and you don't need the spice anywhere else. You can "thicken" the effect by comping it several times with itself, slightly offset in time.

The translucent-plane layers give you the sense of what dust "is" and what the dust is "doing." The spice layer is what conveys the sense that "it is 'dust' that is doing it" (as opposed to smoke, ash or whatever).

If you need "pixie dust" (glittering particles), those are simply another spice-layer added to the soup. A very surprising "thickening" effect can be achieved by comping a layer with another layer of itself running backwards. Since the whole thing is comped, it's computationally very cheap. And fast. Which is good, because "straight ahead" particle-system work is usually anything but... hours and hours of computational grinding for every one of those pretty little pixels, most of whom contribute very little to the pic.

mattswilson
08-24-2004, 10:18 PM
Hey Michael,

thanks for the inquiry, I am still trying to find the time to upload my full site. I will be uploading it pretty soon it will be available at www.velatura.com (http://www.velatura.com) within the next few weeks(If my schedule lets up)

good luck with the dust.
Matt

CGTalk Moderation
01-19-2006, 01:00 AM
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.