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Light, powdery dust advice ...


djwarder

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Hey particle-people!

I'm trying to sim some high-detail dust (or sawdust for a better description) in POPs, but have no idea how to get the nice type of motion & nice, powdery look that is required. Anyone got any tips or examples they could give out please?

Cheers

Dan

ps. This is the best filmed ref I could find online - http://www.artbeats.com/clips/MA114/NTSC

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If all it has to do is fall:

gravity + curl noise + random mass + random pscale + delayed load and 10 or more sims combined.

If it has to do more than fall, use a low res fluid sim to advect the particles + apply the above.

I would say the most important in this is the random mass step. This will make sure the particles start to streak and spread out as a higher or lesser amount of force is used for a specific particle. You'll still need a lot of particles, but unlike with ink or super fine dust, you actually want to have the occasional bigger particle. You may want to consider linking the pscale and the mass together. Also your pscale distribution should be exponential, so you have a lot of tiny particles and a few bigger ones.

You could consider doing two particle systems, one for fine detail and one for slightly bigger clumped fluff - it might be easier to control that way and merge them together at rendertime. Depending on how big clumps you want, you could do the slightly bigger clumped fluff first and use it as emitters or advection particles for the fine dust particles.

Edited by pclaes
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Cheers Peter, that's actually not too far from what I'm doing at the mo, so that's re-assuring. Maybe it's my emitter that's destroying the streaks that could be created using randomised mass, will have to take a look. How much does the emitter contribute to this kind of effect (just falling dust btw, nothing else complex)?

Also, what did you mean by combining pscale & mass?

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I don't know what kind of emitter you are using, but if you are using points, you may be getting stepping artefacts. Personally I like to emit from (resampled) lines or nurbs patches to create my own approximated substeps without having to oversample the popnet. If it is a fast moving emitter you may want to inherit quite a bit of the emitters velocity. Also I would consider creating a second curl noise that has a distance/age falloff to the particles and that is linked to the velocity of the emitter -> If the emitter is going fast, you want the dust to inherit the emitter velocity as well as be affected by "the turbulent air currents generated by the emitter", when the emitter is gone the turbulence should dissipate and only the air friction and global turbulence should affect the dust. The curl noise can simulate that turbulence for you. You can mix some of these forces in a custom vop if you find the default curl noise does not give you enough control.

linking the pscale and mass, simply means that if you have a heavier piece you make it bigger. You probably want to vary your mass only a bit:

mass=fit01(rand($ID)^4,0.8,1)

pscale=fit(mass,0.8,1,0.5,1.5) * global_scale

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Thanks again Peter! I'm starting to get some better results now, looks like I am getting the stepping artifacts you mentioned, didn't realise this was coming from using points as emitters.

Think it's gonna need a lot of tweaking to get results of the detail they want (i.e full-screen photo-real sawdust), but it's a start as I was going totally the wrong way before!!

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