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UCLA Adds Physics to Prat-falls
BaltoAaron writes "CNN.com is reporting on Petros Faloutsos , a UCLA scientist, that has developed a program that creates animation based almost solely on physics. Faloutsos "believes his animation program will one day allow virtual stunt artists to replace their flesh-and-blood counterparts in performing otherwise deadly feats of derring-do." "It's the Holy Grail of character animation. Everybody wants to do it, but there's not a whole lot of it out there right now.""
This guy http://www.q12.org/phd-movies.html did a physical body *and* made it walk with artificial controls. (And he's developed a library for the physics called ODE which makes doing a body falling down stairs about a days work, maybe half.)
People who quote themselves bug the crap out of me -- Me.
You could get into the program and change a variable or two and have your characters looking like they really are on a high-gravity or low-gravity planet, or in the viscous atmosphere of Jupiter, or whatever you like! I'm looking forward to it.
I remember thinking that something about it looked unnatural, even a little cheap. Now I know it wasn't a low budget effect, just a new technique.
While this may one day create much more realistic effect in film, I'm not sure it's quite ready yet. Did this scene stand out for anyone else that saw this flick as a little "off"?
yes i run a goth/punk/emo porn site.
DANCE is a portable, open, plug-in based, object-oriented software package for physics-based character animation. It runs on Linux, Irix, Windows 98/NT and is being ported to MacOS by Joe Laszlo. One of its goals is to provide researchers with a common platform where they can test their control methods and share their results. In addition, it provides the common, yet complex functionality that everyone needs in a physics-based animation system, allowing researchers to concentrate on their research work. Dance has been used for a variety of physics-based applications that include biomechanics modelling and composeable controllers. For more information, please contact the authors.
It's available to download and play with!
There has been research in this area being done for years, much of it presented at SIGGRAPH. There are techniques to animate characters through intricate plots just by specifying behavioral charactics, techniques to apply motion dynamics to characters of significantly different shape, and even "video puppetry" that allows images to self-animate in response to speech. All are a number of years old. All were hailed as holy grails. This just seems to be a case of CNN finally noticing.
At last year's SIGGRAPH, everyone already knew about polynomial textures, because there had been a news story about it. To me, though, the highlight of the show was that it is now possible to walk around with an uncalibrated, handheld camera, and completely automatically get a decent 3-D model out of it (textured, of course). No news story about that.
Years and years...
http://www.animats.com/
Physics-based animation has been a hot topic in computer graphics for a decade. SIGGRAPH made a major award to Prof. Andy Witkin of Carnige Mellon in 2001 for major progress in this field. This involves anmal motions, objects colliding, objects shattering (e.g. Phantom Menace) and so on.
Every computer generted graphic movie thus far has failed
Uh... Toy Story I/II, Bugs Life, Monster's Inc, Shrek, Antz (which I think sucked but did good business)... I wouldn't exactly call them failures.
This is the death of competitive FPS games as we know it. No longer will we be able to change our jump direction in midair, jump 7 feet through windows, run tirelessly carrying 750 rounds of ammunition, and get hit by blast damage through walls.
On the upside, the blood & guts is going to look a lot cooler.
Loneliness is a power that we possess to give or take away forever
Well, the trouble with using it to replace stuntmen has as much to do with the realism of actual footage of an event vs a cgi simulation of one.
That is, there are many other factors that cgi imagery comes no where close to mimicking, so even if tommorow this software let you create completely realistic human animation, it wouldn't put the union out of business yet.
Many of the more spectacular stunts in our favorite action movies...such as the ones in crouching tiger...used the computer simply to composite the scene elements (like replacing the ropes from the flying harnesses), rather than recreate the scene. Or that train crash in Die Hard 3. The computer is often used to combine several "real" footages (like combining the actors on one set and the dangerous stuff on another) rather than do a whole scene, anyway.
However, games could be great with this tech. I have always wanted to see a realistic fighting game, one with actual full physics animation, medical grade damage modeling (and when someone is hurt, realistic degradation of their performance), and the completely unscripted movements that an animation engine like this would allow.
For instance, if someone punched your on screen avatar in the gut, your character would first stagger with the blow, and then shake back and forth as he tries to catch his breath. If you hit one of the attack commands at that moment, the subsequent attack animation would be modified by him still recovering from the blow, as WELL as what the other player was doing. A compltely freeform system. Yes, I know its possible to fake some of this now but there are some obvious limits. For instance, no matter how hard or how light your avatar got punched, he will probably still stagger with the same animation.
And of course the "beowolf cluster" of all these technologies : a massively multiplayer online game where you can run around fighting other avatars like above, as well as casting spells, killing monsters, leveling, looting, camping, kill stealing... All the rest of the good things we come to expect from games of this type
I seem to remember for example that normal character run speed in Unreal Tournament is over 30mph. They also tend to disregard inertia for enhanced control.
Game engines could be modified for spatial realism. The Unreality Project for example. The problem is applying that technology for character models.
Regards
I like teamwork. It's easier to assign blame that way.
Of course, there are definite advantages to putting sensors on someone's body.
If I fall down the stairs, what's going to happen to, say, my right arm, wrist, and hand? Sure, if I'm unconscious, that will all be dictated by physics - I'll flop around like a rag doll and you can nicely see all the reactive forces at work.
But if I'm conscious, how is the programming going to emulate my increasingly desperate attempts to keep from breaking my neck?
It seems to me that a better effect would be captured simply by hooking up motion sensors to a stuntman, telling him to take a five-minute break, and then throwing him down the stairs when he wasn't looking. The "mechanics" realm of physics has relatively simple rules; panic does not. So far, we don't have any formulas for the interaction of perceived danger, temperament, adrenaline, and what have you.
"Beware he who would deny you access to information, for in his heart he deems himself your master."
I'm willing to believe that this is a new and sophisticated tool, though I see there are already a bunch of credible posts about prior art (I go to SIGGRAPH, too).
My issue is that a lot more than physics needs to go into an animation. There's brain up there controlling all those muscles, it's not just a bunch of sticks and rubber bands. A character animator is an *actor*, part of his or her job is to give the appearance of intention to a character's performance.
Falling down the stairs is (relatively) easy. Show me the panic the moment he realizes he's lost his balance and can't stop himself. Does he flop like a drunk or roll out like Jet Li?
You still need to control a character with a human brain, whether that brain belongs to a mocapped stunt man or an animator.
The researcher performed this work for his
Ph.D. thesis at Toronto. Though he is
most likely continuing the line of research
as a professor, the article is about his
thesis work.
That sounds amazing. Does this mean that a formerly HARD AI problem (vision & representation) is now solved?! Do you recall any names or something, so that I can look for more information?
Belief is the currency of delusion.
When you use forces, as you suggest in
the second paragraph, you are not doing
forward/inverse kinematics, but rather
forward/inverse dynamics, a much harder
problem.
And things like trees and jello behave
passively, that is they don't produce any
forces on their own from muscles, motors, etc.
My guess is what you are referring to in the
first paragraph is simple spring-mass systems.
Modal analysis can be used to obtain more
accurate deformations for things like trees.
But if you want to simulate humans, you need
to model the human's muscles as well if the
human is anything but limp. The interaction
can be very complex (especially given closed
loop situations such as two legs on the ground).
I thought Terry Gilliam was the Holy Grail of anima.. oh nevermind..
Somewhere, something incredible is waiting to be known. -- Carl Sagan
Are you absolutely sure you want a fighting game that's realistic? Millions of people would complain about "play balance" in a realistic game. Face it, if you hit someone, physics dictates they're going down unless they take drastic measures to counteract that. And like you insinuated, if they take drastic measures, it leaves them open for more punishment. That's why, in real fights, it's almost always the guy who connects first that wins. And medical-grade damage modeling is definitely something you don't want. In almost every fighting game ever made, hitting someone in the stomach staggers them back, but that's about it. From (unfortunate) experience, getting hit in the stomach actuallymakes one double over and takes you out of the running for a minute or more.
Let's face it...reality isn't fun. It takes a lot of money put from a special effects budget to make a movie look exciting. And that's because in real-life, things just aren't that cool.
4-star general in a one-man army.
Faloutsos' work is not actually focused on the physics models, but on the control programs for the virtual actors. This allows dynamic, force-based animation (as opposed to kinematic, position-based animation). Each model has a set of controllers for various tasks like walking, running, jumping forward, moving from a prone position to a standing position, etc. Each controller knows its "competencies" -- the conditions under which it can successfully guide the model. These are used to hand off control from one controller to the next as the model goes through a complex motion or reacts to external forces.
The sample movies that Faloutsos showed were mostly unscripted. They would start with a model in a simple standing state, which would then respond to user-controlled forces like pushing or throwing simulated balls at the model from various angles. Various balance-recovery controllers would take over depending on how the model was displaced; if none of them were succesful then the model would fall down, and then use one of its controllers for returning to a standing position. All of this appeared incredibly realistic and human.
Also, as another poster noted, DANCE is available under a "free for non-commercial use" license (not free under the FSF or Debian definitions, but a good deal in my opinion). He encouraged us to try it out, explaining that research like his has suffered from a lack of common infrastructure, leading to a lot of reinvented wheels. He expressed hope that the DANCE framework would allow more innovative research with less duplicated work.