Making Animated Fluids Look More Realistic

brunascle writes "Technology Review has an article about recent advances in animated fluid dynamics made by Mathieu Desbrun, a computer science professor at Caltech. 'He and his team are developing an entirely new approach to fluid motion, based on new mathematics called discrete differential geometry, that use equations designed specifically to be solved by computers rather than people.' Desbrun explains that the currently in-use equations for animating fluid dynamics were not developed with computers in mind, and were simply reworkings of older equations. He claims that his new equations use about the same amount of computer resources, but with much better results. The article includes a 5 minute (flash) video demonstrating various results using his equations, ending with 2 fascinating and vivid displays: the first of a snowglobe, and the second of a cloud of smoke filling a volume in the shape of a bunny."

Comments

this is the real deal

[Anonymous Coward]

I saw a presentation on this by Desbrun last year. The absolutely most amazing thing about the approach taken is that there are multiple naturally appearing ways to get values for different differential operators. This can let the cfd practitioner get a real estimate on numerical stability. That may not sound like much but in flows in which turbulence becomes non-negligible that is huge because it's hard to tell if what you see in the model is real or artifact. All that aside, he's a reasonably nice guy -- very much in the old Cal-Tech mold of "be wicked smart", "don't brag", and "do amzing things to get noticed". Good to see the "get noticed" part is starting to happen.

Need "Before" and "After" animations

[dpbsmith]

The animations are impressive, but so was the animated water in Titanic and A Perfect Storm. I wish they had featured a comparison of the same animation, performed with the same computer resources, using the traditional and new methods.

Real-world applications?

[RobertB-DC]

While I'm sure the gee-whiz factor of more accurately simulating Lara Croft swimming is the hook for the story, shouldn't it at least pay lip service to real-world applications of this new technique? Wind-tunnel testing is one area that currently requires massive physical facilities, and would clearly benefit from this research -- air is a "fluid", too. You could even apply it to thicker fluids, perhaps devising new ways to fabricate items from glass or non-destructively test metal part designs for weaknesses that wouldn't have been otherwise revealed.

Though the importance of properly modelling Lara Croft's swimsuit can hardly be overstated.

Roughly analygous to FEA?

[EndingPop]

They mention "discrete differential geometry" in the article. This sounds a lot like a finite element/difference approach to solving fluid dynamics problems. I'm wondering if they are actually just solving for true phenomena using a simple FEA code or the like. Later when they start talking about flux (really, they're talking about calculating vorticity), they mention this same sort of discritization used in engineering.

Re:Roughly analygous to FEA?

[jackbird]

It offers no speedup in computation time, and probably has no parallelization opportunities beyond those normally there in fluid dynamics. However, it *does* produce better-looking solutions as all of the conservation laws are met.

To us pretty-pictures guys, a better-looking solution in the same amount of time IS a speedup, because otherwise we crank up the quality higher and slow down the calculation in order to get the results we want.

(Or fake it some other way - for example, Blizzard made a trailer for warcraft 3 that showed two dead characters' blood mixing in standing water. Instead of killing themselves with a CFD solution, they shot white latex paint dissolving in a black kiddie pool on video, and used the footage as a mask to do the effect in post.)

I was hoping for a different bunny

[spun]

I was hoping for Lenna. Simulate me a steamy Swedish playmate, and then show me what happens when I take her top off.

Never mind that she's over 50 now, married with 3 kids...

Re:Fluids in games

[ponchietto]

You would be surprised... we are already there.
http://graphics.cs.uiuc.edu/svn/kcrane/web/project _fluid.html/