Avalanche


#1

Currently in the middle of a project with an FX shot that calls for an avalanche, that chases a snowboarder down a mountain. 97 frames long. Im wondering if anyone has any ideas on the best way to accomplish that thick rolling cloud look. We’ve tried particles and fluids, fluids looking a lot better, although very costly for render. The particles always seem to come out looking like smoke instead of a nice thick cloud.

We’ve tried using the puffball, with some tweaking. The problem is in the first few frames of using the puffball, it looks like its exploding. What attribute is causing this and how can I remedy this so on the first frame its nice and full looking. It also lacks the look of actually interacting with the ground , almost like it just floats along.

If anyone has any other ideas, advice on creating an avalanche Im all ears. Any help is would be appreciated.

-Justin


#2

I’m not much of a fluids guy but the Special Features for Ice Age have a nice breakdown on how they did theirs at the beginning. The way i’m picturing it is you’d have the hardware smoky particles as well as the fluids. yeah you’re killing on the render time but it will look better.


#3

Thanks for the advice. Managed to get the fluids all figured out, and achieved a very good avalanche cloud look. I did manage to reference triple X footage as well as the ice age footage both of which are very helpful.

I have numerous chunks of ice and rocks, shooting through the front of this avalanche which is composed of a bunch of fluid containers. The problem im getting now is that the rocks are popping when they go through the fluid containers. Is this common to fluids? I was hoping that the voxels that represent the fluids would be able to show varying degree’s of transparency. I hope Im making sense here. If anyone has any suggestions Im open for any ideas, responses, opinions.


#4

check this thread:
http://www.cgtalk.com/showthread.php?t=155001

in there we are discussing the possibility to apply a fluid shader to particles.
that could very well work for your project.

cheers

alexx


#5

Thanks alexx for pointing me to that thread. I actually read through it a few times. I’ve used the method you’ve discussed although I found that using the fluidshader on particles was just as expensive as using normal fluids. Although that thread is full of excellent information. Thankyou.

My main concern is the popping that occurs when a small piece of geometry goes through the fluid container. I believe my problem has to do with the speed that my instanced rocks are flying through the fluids. In one frame the rock or object is totally obscured by the fluid, and the next frame its completely out of the fluid, which in turn is causing a popping to the eye. I’ve tried to slow the rocks down as much as I can, but to no avail they still give off a pop when they breach the fluid container. Any ideas are welcome. Im sure the real answer here is to rebuild the particle part of the system using a different technique. Thankyou in advance for any ideas, opinions.


#6

Perhaps your popping would be helped by 3d motion blur on the rocks(2d wouldn’t work in this case).

Duncan


#7

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