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MartinRomero
05-04-2007, 06:49 AM
Hi guys,

I am working on a school project where I have a helicopter landing on a dusty field. I am trying to go after an effect like the one in "Black Hack Down". in Maya, I tried using multipoints and some fields such as gravity and turbulance but it does not seem to look right. I am familiar with Particle Flow however I kind of need some help on getting the right flow to get this result.

I have attached an image of the scene I am working with.

Thank you guys.

BrandonD
05-05-2007, 02:32 AM
Check the sample files that ship with your copy of 3dsmax. Myself and LazloS at one time or another made sample files that show how to do this technique. Here's the idea off the top of my head:

Making the Emitter
Make a Circle that roughly matches your rotor diameter, add a MeshSelect modifier and make it non-rendering. Align it to your helicopter object, parent it, then move it down to the ground object so it lies flat on the ground. Now disable inherit motion from parent in Z, so that now, when the helicopter moves, this circle (actually a disk) will always be underneath the chopper and always aligned to the ground (this get trickier with uneven terrain and you have to use a Conform).

Making the Motion
Use PositionObject to emit particles from disk surface. You can animate the Birth Rate by hand or use a Reaction Controller (or expression), the idea being that the birth rate increases as the object gets closer to the ground. You can cheat this easily by making the ground at 0.0 on the Z axis so that the value increases the closer you get to 0 (amount - distance). Now add a Wind SW set to Spherical with Decay (try 0.01) and snap it to the center of the disk and parent it. Apply this to your particles and now you have particles blowing outward radially. You'll have to tweak this a bit to get the right look. Add a Drag and some turbulence and you should be in the ball park.

Making the Dust Look
There are many ways to do this. Volumetrics look best but can be a pain at times. Two geometry methods are to use ShapeFacing to make small opacity mapped squares that always face the camera. Use a Particle Age map in the opacity mask so that they fade over time (don't forget to use a Delete operator). Another method uses spheres instead of cards with opacity falloff based on normal. Do NOT raytrace shadows through either of these methods.

That's the idea generally.

MartinRomero
05-07-2007, 06:58 AM
I just want to say thanks a lot man for your great piece of information. I have started the whole thing in Maya but I think that I will have to go and do the whole thing with Particle Flow in Max. It's not going so well in Maya anyways, lol. I really want this piece to turn out great so let's see what happens. Thank you so much again and have a good one. late

MartinRomero

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