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Anti-Distinctlyminty
11-11-2005, 11:30 PM
Hi all.

I have an animation that shows a small cylinder of explosive material contained within a small clear perspex holder which is open at one end exploding a la high speed camera footage style. I'll attempt to explain more clearly: When an explosive detonates, its entire surface just kind of shoots outwards at very high velocity. The ebst image I could find on the web is this one http://www.lokiconsult.com/images/iccd.jpg

I need to recreate this in LW. I tried one method already, by convering the surface in points and putting hypervoxels on them which grow over time. This achieved the desired effect, but in order for it to look good I had to put several thousand hypervoxels on the surface (due to the fact that it had to look like the surface just disintegrating & expanding, so the surface had to be covered to retain the original cylinderical shape).
However, this solution was unsatisfactory due to the large amount of HVs & rendering time (all intersecting with each other after a few frames which increased the rendering time even further).
I've tried dissolving out the large number of HVs so just a few HVs can 'take over' so to speak, as after they've become large enough, the original cylinder shape no longer has to be maintained. But until they're fully dissolved, the rending time is huge & I cant dissolve them out too quickly or the viewer will notice the jump between the large and small number of HVs.

This one's really got me stumped - any suggestions?

Thanks in advance for any replies.
rwhunt99
11-12-2005, 06:51 PM
This is just a suggestion; Maybe startout with large number then using a particle age based gradient you can cull the numbers down to a few "hero" HV's that will grow and keep the mass at the desired size. You can try going with half the points then clone them and apply the gradient while enlarging them with another age related gradient. Does that make sense to you, I'm not sure if I explained it right?
gerardo
11-12-2005, 11:26 PM
If I understand well, maybe this Stefan Bredereck tut can give you some ideas:

http://www.brederock.com/BladeFX_Tutorial/Content/BDROCK_BladeFX_Preview.jpg

http://www.brederock.com/BladeFX_Tutorial/index_eng.html

don't know if this technique is viable for a slow motion shot, but maybe you can use several layers of the same object (different sizes, normal displacements and AVTBump) to get more complex look for the explosion/desintegration mixed them with HVs (but without so many particles).



Gerardo
Anti-Distinctlyminty
11-13-2005, 02:27 PM
rwhunt99: Hmmm, I'm not sure that will be any more efficient than the method I tried, but I will certainly give it a whirl. IIRC you cannot apply a texture to the dissolve channel can you? How would I get the particle to dissolve out...though I think that the Thckness value may do the same thing.

gerardo: I'll take a look and see if that method will work, though I feel that many many HV's would be needed.

Thanks though - keep the suggestions coming :)
gerardo
11-14-2005, 12:11 AM
gerardo: I'll take a look and see if that method will work, though I feel that many many HV's would be needed.

Perhaps, but I guess that's depends on your take and requirements, the idea is to use the same object surface to fake the first particles disintegration and then replace them by HVs when they should be more incandescent, what suppose less particles :)



Gerardo
Anti-Distinctlyminty
11-14-2005, 11:38 AM
Gerardo, forgive my ignorance, but what is an AVTBump?
gerardo
11-15-2005, 01:14 AM
You should have seen this nice plugin some time ago, is a good fake of micropoly displacement:

http://forums.cgsociety.org/showthread.php?t=210027



Gerardo
Anti-Distinctlyminty
11-15-2005, 09:23 PM
Darn - the plugin is a pixel filter. I'm rendering in FPrime unfortunately, so I wont be able to gain access to the filter.

I may have figured out what was causing the huge render times though - many hypervoxels that were being refracted. I'm taking those ones out and will try to find another method for them.

I wish I could post pictures - would be so much eaisier to explain.
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