View Full Version : PFlow smoke-machine turbulence..

10 October 2007, 11:28 PM

I want to create smoke-machine type of ground lying smoke similar to the following..

I`ve been messing around with pflow and afterburn, using wind SW with turbulence and stuff like that. But i`ve encountered the following problems that i`d really like to work around..

A) How to reproduce the wave-like pouring out of the smoke particles (puffs).

B) How to reproduce the change from small localised noisey puffs to flat+smooth ones.

C) How to have the whole thing ebb+flow in it`s own natural way.

The `look` of the particles is obviously as important as the particle `flow`. Afterburn provides lots of options but getting a balance between nice puffs and a good flow is difficult. Also getting a reasonable distribution of small particles without the larger smooth areas getting clogged up is an issue - do i really need 100k+ particles?

Any help/tips/suggestions would be much appreciated.


10 October 2007, 01:37 AM
If pointwise stated then:-

A)You can use the wind operator with turbulance for the wavy effect.....I would recommend using two operators and playing with them.
B)Set a delete operator on your Pflow and specify the time you want the particles to die out.And then go to afterburn and enable the AFC curve thus specifying the starting and ending result for each particle.Which means that if you say Sphere Initial size would be 1 and final size would be 10 and the delete operator in your PFlow is set to 100,the what AB will do is,it will take into account the life span of each particle and set the size from 1 and will make it expand to size 10 till the 100th frame from its birth.
C)Have you had experience with Fume FX,if yes then I would say to use Fume for the light smoke you see after the small puffy smoke and use the Fume Gravity to make the smoke remain near the ground,because Fume gives a much natural flow since its based on Fluid Simulation.The render Fume's smoke and AB's smoke and composite them.

Hope this helps,

10 October 2007, 01:13 PM
Thanks entrancea. However, your points don`t seem to address what i`ve said directly.

A) I was playing with turbulent wind, but how do i get the particles to birth in the sortof wave formation (i`m thinking maybe animate the birth scale up and down). Only thing is i dont think i can animate the scale in pflow and use the radius AFC in afterburn?

B) I have played around a lot with the AFC curves including the squash ones but simply making them grow and/or squash isn`t enough (this is the heart of my problem)

C) For the natural ebb+flow of the smoke after it pours out, should i use inter-particle collisions? How could i recreate this - i`m still thinking!

Don`t have fumeFX, but i`d like to think that it could be done with Afterburn.. would maybe metaballs be better for this? Like i said the `look` of the particle puffs in Afterburn is the real heart of my problem, and balancing AFC curves with a true dynamic pflow system.. can it even be done??

10 October 2007, 04:57 PM
If you don't have afterburn you'll probably need to do some scripting to drive some atmospheric gizmos with your system.

Afterburn makes this type of effect fairly simple. (About a 5 minute project.) Or you can search around for my "Rifter" script which is somewhere around here to see how I drive the atmospheric gizmos with pflow. Or go to BoboLand and look for his basic "Particle motion transfer to scene objects" or something like that. Then modify his script to your needs. Even if you have tons of ram that's more particles than most systems can handle if you're not pushing gizmos. If you do go the particle route though you're going to run out of particles and you'll need more than one PFSource.

One question I'd have to ask though. Is this an action shot or a single frame render?

10 October 2007, 04:59 PM
To get the ebbe and flow set a wind to 0 and use some turb at a low setting.

Edit: then use the animated shape within AB. Can't remember the option but it's a little check box that changes the shape according to the direction of the particle movement. Drop down the detail a bit and bring up the blur and use some Mblur on that event as well. Set the noise size about 2<AB size.

You'll also need to play with the step size and detail to get this to look right.

10 October 2007, 09:18 PM
Thanks Supremepizza. I think blur might be the key to achieving the transition between noisy/bumpy and smooth don`t know why i never thought of that (other than the fact i`m new to afterburn)..

I want to try and squeeze as good as possible result out of afterburn and pflow without using additional scripting (i feel it`s a good way to learn the software and it`s limitations), for the time being at least.

I still have unanswered questions, so if anyone cares to offer any insight that`d be cool. Either way i`ll go ahead and keep playing with it while i learn new things.

10 October 2007, 01:33 AM
You'll also need to play with the afc for the for the opacity. I can't remember exactly. I'm in the middle of a scene now and will get back to you when I get to the AB tomorrow.

One thing that might help would be to create a seperate PFlow for that low density/velocity stuff and use the same 0 velocity wind on it as you use on the higher velocity flow. That will tie the two together while still giving some velocity to the more dense stuff with an additive wind in a seperate force operator. In the lower density flow force operator you may need to bring down the influence to 750% ish but it will still have the same frequency. I typically use two flows like this.

Hope that makes sense to you.

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