Physics for Animation 101 Physics for Animation 101

Physics for Animation 101

A short piece about Alejandro Garcia, a professor at San Jose State who teaches physics to animation students and is now consulting DreamWorks animators on how to incorporate believable physics into their films.

(via CatHicks Twitter)

  • Animation it´s very much funnier when physics are unbelievable.

    • CJ

      I don’t think many people realize that in order to be able to make unbelievable physics appealing you have to understand and master how they work in real life. Otherwise you end up with a horrid mess.

      So ok, Bob Clampett kind of physics is fun. But how can you break the rules if you don’t understand them, or master them in x medium?

      Promote the possibilities of this project. You might be surprised, and in a good way at that.

      • You only have to understand cartoon physics – which is the physics of the imagination.

      • Juan Carlos Valdez

        I agree that having a better understanding of physics will help the animation look better. Especially if you bend and break those rules to make it more amazing. But the problem is that cartoons are cartoons. They are not part of the real world. I find it funny that so much importance is put into making animation look more real, instead of allowing the animator be artistic and creative. The argument isn’t how to make animation look “real” but to make animation look natural. Whatever happened to Suspension of Disbelief? Why does everything now have to be over explained so that it makes “sense”. No one questioned when Wile E. Coyote would walk off a cliff and still be walking in mid air until he realized that he wasn’t on solid ground. There are cases when real world physics do not and can not apply to animation. For example, Art Babbitt’s angry walk. The human anatomy does not work the way Art Babbitt animated that walk. But it looks right and awesome. Squash and Stretch and smearing inbetweens does not happen in real life as it does in cartoons. But in animation, it’s brilliant! In the end try not to over think every little thing, animation is an artistic medium, not everything will be perfect. Because perfection is in the imperfection.

      • Jasmine

        In order for suspension of disbelief to occur, there has to be something believable in the first place. Yes, cartoons defy physics, and Garcia and Dreamworks understand that completely. In order to break the rules effectively, you have to first understand them.

        Additionally, there are times where physics is used as a basis, even in obviously imaginary and fantastic worlds. When rays of light poke through the trees and scatter onto the forest floor, that’s physics. It may be embellished and exaggerated for effect, but it does abide somewhat by the laws of physics. And if that basis didn’t exist, and animators put light rays in ways that don’t coincide at all with reality, that would break the suspension of disbelief: The audience would catch on to something being “off” without fully understanding what. It’s kind of like the uncanny valley, in that sense: We may not know the details of human anatomy or the laws of nature, but we’ve had enough experience with them that, when we encounter something that is slightly off from our instincts, we reject it and no longer find it appealing and believable.

        Not to mention, not all animation is found simply in cartoons and 3D animated movies. It can also be found in video games and in live-action movies. Many video games nowadays strive for as much realism as possible, perhaps not necessarily in explosions and the like, but more in the environments, helping with the immersion of the player. Likewise, live-action movies such as 300 and Avatar made great use of special effects and animation; imagine what either movie would be like, were it not for incredibly talented and knowledgeable animators behind them. Sure, they may involve fantastic environments, but there has to be some reliance on principles of physics and anatomy that come into play.

      • Suspension of disbelief depends on your imagination. If you tend to believe in everything, your disbelief will be suspended. I believe in unicorns.

    • Inkan1969

      Rafa, Joe, I think humans have an instinctive knowledge of how physics works. They don’t have to solve the Universal Gravitation Law in order to have a concrete idea of how an ball moves when it’s thrown in the air. I think cartoon physics is at its most appealing when viewers can associate real physics experience with the gag.

      Like the gag where someone doesn’t fall until they look down. You should be able to animate the legs to convincingly look like they’re walking on a solid surface. And have them subtly speed up as they fall. Hmm, I just saw a funny “Gumball” ep where Gumball hit poolwater with a sudden stop. That wouldn’t be how it would happen in real life, but it did recall how the fall would’ve happened on a solid, and remind people about how a belly flop stop is very painful (You have a LOT more force stopping you if you bellyflop than if you dive hands first like a pro.).

  • NC

    Maybe they should be teaching it to the people who are actually doing it. Underpaid Koreans and Indians, because god-knows they need it!

    • Inkan1969

      I’d be in favor of universities forming exchange programs where physics profs can visit overseas colleges to teach basic physics for those studio artists.

  • There Hollywood goes again, trying to turn something into something it’s not. The technology we have is getting greater and greater, we could probably do things the likes of Clampett & Jones only dreamed of, yet for some reason are trying to make stuff look more like real life. It’s just plain strange.

    • Andrea

      Wait… you think teaching animators how to animate weight believably is “just plain strange”? Have you never animated a bouncing ball or a swinging pendulum or a wave to learn about the principals?

      • No I think it’s strange that we have technology to produce vivid, highly creative worlds and we have producers of these worlds trying to get images as close to reality as possible. We can already make physics in cartoons look believable yet other worldly. They’re called Roadrunner shorts.

      • dig

        Take a closer look at the Roadrunner shorts. They use real world physics constantly. Why do you think the anvils feel heavy? Why do you feel the coyote’s feet skidding on the ground? Why do you feel the pain when he gets hit by a train or truck? These are real physics, caricatured and exaggerated beautifully and applied to a cartoon world.

    • JG

      Your average 3D has a different “texture” and expectations than hand drawn animation. It relies on believability more, it has to convince it’s real. Physics, anatomy, biology, mechanics – things like that are very relevant to it.

      And the knowledge becomes even more important when you’re dealing with anything else than animating a character performance – rigging, lighting, sfx, texturing.

  • Matt

    DreamWorks Or BoringWorks?

    • Ethan

      You see, this is what happens to the community of CB.
      You bring these people here.

  • This guy should talk to the people who do the IRON MAN movies.

    Iron Man slamming to a landing, going from a zillion miles an hour to 0 in an instant, would puree Tony Stark inside the suit. He would leak all out of the bottom if it.

    • Funny you mention that because I use exactly that example in my class!

      • Funkybat

        I would say the physics in a lot of 3D animated features are actually more believable than a lot of “live action” VFX-laden action/adventure films. I spent the last third of Die Hard 4 and Iron Man 2 struggling to believe that characters who should have been dead by now were still running around, barely winded.

  • 2011 Adult

    I can excuse how CG artists working on photo-realistic films cannot make the audience believe “it’s a cartoon”, because it wouldn’t work with the visual style, and the tone of their films. I, however, believe that physics were meant to be broken in order to exaggerate some aspect of a movement to get a point across. But then, I suppose that’s why I work in 2D, cartoon-y projects.

    • 2D cartoony animation also employs a mastery of physics. The ideas of squash and stretch and straights vs. curves are rooted in physics. How can you tell the difference between something that’s stretching and something thats growing or morphing? Physics.

      Whether you realize it or not, when you squash and stretch you are applying an understanding of mass and physics. That’s all that’s being taught here. Nobody is trying to teach animators how to be cold computer simulation generators.

    • Inkan1969

      You need to know what the rules are first, before you can break them. I’d see a physics for animators class as a provider of the basic tools of describing real physics. It’s then up to the artist to figure out how to modify or apply those tools to make one’s own artistic statement.

  • Ethan

    I am amazed at the number of people jumping in and spitting at basic knowledge about how the world works around you. Don’t teach me anything! Don’t teach me anatomy either, I only want to make cartoon characters!

    If you don’t understand basic physics, you won’t be able to exaggerate it correctly. Lazy Bastards.

    • CJ

      Exactly, Ethan! Couldn’t have said it better myself.

      As Michael Barrier has stated and I para-quote this.

      “John K followers are like a cult, wanting everything to be ‘cartoony cartoony’…”

      It was something to that effect.

      People want cartoons but don’t want to understand what goes into making a cartoon. That wont get you far.

  • It seemed like older cartoons wanted you to always know you were watching something completely removed from reality, but now they are emphasizing believability. I think people like Clampett bending (and breaking) physics was more fun.

  • Daniel Shock

    You have to know the rules before you can break them.

    • Professor Widebottom

      Is that a rule?

      • Inkan1969

        Sure. Sorry, Daniel. I didn’t see your comment and so I said the same thing elsewhere. Remember that Picasso learned to paint like Michelangelo before he could then paint like Picasso.

  • JMatte

    Agreed with many posts above: learn it properly before you can break it.
    And there’s still logic. For example: cartoony character may not have realistic anatomy, but they still have basic constructs. No one here would deny the good side of doing life drawings. A little bit of physics never hurts to add to observation.
    It applies to everything as Andrea said. Anyone who had to animate a waving flag that looked halway decent had to formulate how wind moves a piece of fabric. It applies to fx- think of all those water splashes, explosions, smoke clearing. Everything.

    Or maybe I just really like physics. Ha!

  • Damiano: my animation teacher (Tahsin Özgür) told us “Animation always follows the laws of nature – unless it’s funnier otherwise.”

    And it’s not about incorporating correct physics formulas into CGI scripts. It’s about getting it “look right” which is much more difficult.

  • Oliver

    Dreamworks wants physics? Well here’s a thought:

    ‘Megamind’ / ‘The Incredibles’ = (an exceedingly tiny number)

  • Clement

    The next thing we need is an animation Chernobyl.

  • Two quick comments:

    * In “Chuck Amock” Chuck Jones nicely describes how he used his knowledge of animal anatomy in formulating appealing characters. My goal when teaching physics to animators is to give them a similar tool. But I always encourage them to not be slaves to reference.

    * All the studios have scientists in R&D as well as scientific consultants, ranging from astronomers to psychologists. The National Science Foundation has now recognized the importance of our industry and is supporting education that overlaps the arts and sciences.

    Alej Garcia

    • Animation is a cross-disciplinary communications medium – and your work is greatly appreciated.

      The negative reactions, in my opinion, is the general fear that CG animation is pushing closer to live action and reality, and away from the “cartoony” and the surreal.

      Even though I fall into the “cartoony camp”, I definitely believe that CG would benefit by following sound scientific principles. For, from the onset, computer graphics where developed to mimic reality – and not mimic cartoons. (read Computer Graphics: Principles and Practice
      by James D. Foley, Steven K. Feiner to understand this historical context.)

      So, those who fall into the reality camp, definitely know your physics.

      And for those who fall into the surreal “cartoony” camp, screw reality!

      But remember, even if you go with the surreal – that physics is an unavoidable component of all animation (including experimental), since the one essential component of ALL ANIMATION IS TIME.

      Limes regiones rerum

    • You should rephrase your second bullet point to “some studios”. When you say “all studios” you are taking an extreme position.

      The big CG production studios have R & D consultants across the spectrum of sciences – the bulk of which are computer scientists and programmers.

      Smaller boutique studios probably can’t afford to. (but I do think Spumco works with astrophysicists occasionally).

      • You’re right; most smaller studios don’t have R&D scientists or use science consultants. Then again, I’m the crew physicist for my friend Dave Chai’s “House of Chai” studio, which produced “Enrique Wrecks the World.” My fee: A couple of beers.

      • I know David Chai from Michigan. Meet him couple of times at some life drawing sessions – but I never got beer out of him.

        btw – lobby your science buddies to hire animators! (maybe you already are…). The hiring situation should work conversely too … We need more independent animators explaining science with animation.

        Just imagine… if physics where explained to kids with entertaining animation at an early age your job would be so much easier.

      • JOe, It’s happening. There was a nice article in the New York Times describing an example:

        The fact that the National Science Foundation is funding education initiatives for animation artists tells us that the science community sees the potential. Dave Chai’s “Green Ninja” project is another example.

    • Inkan1969

      Wish the scientific consultants had more say in “Armageddon”. :-P

      • Just imagine if scientific consultants had their way with Star Wars…

  • This is great! You really have to understand the rules before you can effectively break them. Show me 5 of the very best caricature artists out there, and I’ll how you 5 people who really understand facial anatomy and human facial features. The worst ones haven’t taken the time to study this. Same with gravity physics.

    One pet peeve I see in CG animation a lot is when one character is riding another character like a horse. The horse doesn’t have it’s own gravity field! Stop making it look like the rider is superglued or magnetized to the horse!

  • CC

    I completely agree that you need to understand physics to create believability (and with that understanding you can create worlds with it’s own laws of physics). Animation needs to convince their audience believability (from Iron man, to the Looney Toons).
    This video brought up, for me at least, that there is a problem in CG. It’s really difficult to break reality because it is so realistic. For example when I watched Tangled there was a moment when the horse lands from a great height, and I thought to myself “that is impossible”. That’s bad.

  • J.m

    Hopefully all that will be fixed with MoCap Animation…just for 3D I say…

    I think things like the incredibles and Megamind could’ve been done MoCap. No doubt…keeping the style of course, not like the shitty sort of realistic one imposed by TinTin

  • Knowing the physics can make you a great animator.
    Not knowing the physics can make you a great animator as well.

    • Ethan

      Praising ignorance as a virtue.

      This must be the worst nightmare of any teacher. Ignorance is an artsy crutch to help break away from the rules without knowing it, without having to think about it. Eventually the artist will hit a wall.

      I can only imagine a young animator fresh out of school going to a job interview at a big studio and say “I don’t want to know anything about physics, because that makes me a very artsy animator”. What are the chances of getting the job?

      • With CG, many say you don’t need to know how to draw. I think that is ignorant as well.

      • Ethan – I know designers that know nothing about anatomy but they are amazing designers. I know actors that never went to a school and they are amazing actors. I know animators that never learned the rules of inertia and they are amazing animators. I know musicians that can’t read music and they are amazing musicians.
        And vice versa.

      • Ethan

        I can tell you right now, that those musicians do not play as part of an orchestra. They cannot.

        The reason they are good is not because they don’t know. If you need a tool, and you don’t have it, you’ll have to screw a nail. Of course, if you choose your projects so carefully that you’ll never need that tool, it won’t make any difference.

      • Paul McCartney

      • Ethan

        He wasn’t staff in a symphonic orchestra at all, he could never be, he’d be a horrible member of the orchestra. You avoided my point. He wanted an orchestra, and someone else did the writing work for him. If he could read and write it would have been easier for everybody.

        Do you honestly believe McCartney was good BECAUSE he couldn’t read or write ?

      • My point is, as I said in my first post, that you could be an amazing artist even if you don’t know (or studied) the technical side of your profession. And that I think is a fact.

      • Ethan

        No you didn’t, you said “not knowing… can make you” which is what I was arguing about. It’s kind of an explicit phrase structure. No problem, case closed.

      • Gabriele, I’ve worked with models and rigs created by modelers/riggers who had an inadequate understanding of anatomy, and their rigs were defective at best, and unusable at worst. I’ve worked with designers who had no art training, and inevitability their designs were improved by someone with real art training (unless the key to their design was that it look ugly and childish).

        We can all find exceptions to the rules. Freddie Moore is famous for his relative lack of artistic training when he started at Disney. He was a ‘natural.’ But he also improved once at Disney, were he participated in the intensive studio-sponsored art training. There are also those who debate why his career plateaued so quickly, and people he worked with pointed to his lack of training as one reason for that (others claim he was undermined by his peer’s jealousy, while some point to his alcoholism). In any event, when I look at Freddie Moore’s animation, I can see he understood anatomy and physics just fine, even if he couldn’t articulate it himself.

        The fact that there are exceptions doesn’t mean ignoring fundamentals is a viable path for most. If you can tell me that Paul McCartney didn’t study the music of others, and didn’t practice to develop his skills, and didn’t improve from that study and practice, then I will grant you that he supports your case. But the fact that he couldn’t read or write music is like saying that a writer who cannot spell cannot be a great writer. McCartney could hum and sing his compositions, and someone else could then score them and write it down. This is exactly like someone who understands physics explaining why an intuitive animator’s work is successful. The animator may not be able to explain it, but that doesn’t mean they aren’t applying the fundamental principles.

        I wonder if you think McCartney’s music couldn’t be written down. Of if you imagine that, had he later understood how to write the scores himself, if that would have diminished his talent and creativity? That seems to be a nonsensical proposition. His ignorance of writing/reading music turned out to not hold him back, but it there’s no evidence that it was a part of his success.

        So your statement “Not knowing the physics can make you a great animator as well” is flat wrong. There are successful animators who understand the laws of physics on an intuitive basis, but their lack of conscious understanding of those laws is NOT why they’re able to animate successfully.

        Though I’m curious — perhaps you can name a few ‘great’ animators who ignored any pretense of real-world physics in their work. And mind you, that is hardly the same thing as an animator understanding physics but manipulating and exaggerating it for strategic effect, the way people like Tex Avery and Chuck Jones did. So please, give us some examples of animators who prove your point.

  • MyssHydra

    As a fellow SJSU student and ShrunkenHeadMan member,I offer my deepest respects to Prof. Garcia and the Physics of Animation program. I understand the benefits of learning the basics, as has been said already in this thread. Can’t wait to take the class!

    Keep up the great work, Garcia!

  • Manu R

    Disney animators used to watch life action footage frame by frame to understand how for instance a horse walks. They were both analytical and artistic.

    But if I follow the logic of a lot of the people in this thread, they did it all wrong, they should have stuck with rubber-hose animations.

    • Funkybat

      Before Snow White, pretty much all animation was “rubber-hose animation” and it was considered normal, because it was “funny.” The strange thing is that one of the very first animated films ever, McCay’s “Gertie” was far more anatomically correct and realistic than 99% of what came after it in the following 20 years.

      The point of “know the rules before you break them” has been amply made earlier in this thread. In addition to that, I would say that the debate about “believable physics” vs “cartoon physics” comes down to style. Something like Ren & Stimpy depends on gonzo physics and inconsistent physical constants, massive shape/volume deformations, etc. Part of the genius of R&S was that this was done in a careful manner, as opposed to the mess that usually happens when novices try to “draw wacky.” The characters and the physics were elastic, not amorphous.

      In most 3D animation, as well as “classic” Disney-style 2D, believable physics, consistent shapes and volumes are more important. It comes down to “what kind of universe do I want this to be?”

  • I’ve chatted with Alej a few times, and he’s doing a great job of approaching basic animation principles in a systematic, logical way. It’s too bad that some people see this demystification of the art of animation as a bad thing. As an undergrad, I was a physics major who took a lot of art classes, and as an animator I use that knowledge of physics at least as much as I use my art skills. It’s funny to me that some of the same people who will talk in awe-filled tones about the Don Graham Action Analysis lectures at Disney during the golden age will dismiss courses like Alej has put together.

    People like Bob Clampett, Tex Avery, and Chuck Jones intuitively understood and applied real-world physics expertly, as several people here have pointed out. Otherwise, the moments when they willfully broke physical laws wouldn’t have been funny. There’s a huge difference between ignoring physics, and tweaking/exaggerating reality for entertainment value.

    Many of the classic principles of animation can be easily be understood as physics problems (slow in/slow out, overlap and follow-though, arcs, many aspects of anticipation). People may rebel at the idea that they’re studying physics when they are mastering these concepts, but that’s what they’re doing.

    Not that there weren’t/aren’t animators who often chose to ignore physics. Jim Tyer comes to mind as someone enjoyed breaking as many rules as possible, and some of the appeal of his animation is the other-worldliness of both the physics and the distorted drawings. But then, Tyer never had to hold an audience’s attention for 90 minutes.

  • Keegan

    I wonder how this man feels about Looney Tunes…

    • I love Looney Tunes and grew up on them. When I came to the US as a kid I learned English from watching cartoons.

      • Keegan

        That’s sweet man, Looney Tunes are awesome.

  • Markus

    Isaac Newton figure it out the animation principles centuries ago : )

  • Roger Freedman

    For those who object to the notion of physics playing a role in animation, I encourage you to glance at the web site for Professor Garcia’s course ( as well as at a recent paper of his on the subject ( I suspect that you’ll be pleasantly surprised.

  • Professor Widebottom

    It’s all about context. However, the point being driven home here is about not losing an audience and the way to do that is to make it look *real*. Oh really? Then why do animation in the first place? Get a camera and shoot or do mo-cap.

    There’s something about talking about technology that gets ahead of what entertainment is. In other words, we’re risking serving the technology and not the vision. The tools are amazing buy why does so much of the output resonate so shallow and generic?

    • Totally. The technology was suppose let us explore the further reaches of our imaginations. Instead we are focused on simulating reality. Well, I live in reality – it would be nice to go somewhere else for a change.

      • Ethan

        Where’s my pet dragon?

      • he’s sitting right next to you!

      • Ethan

        It’s a she :)

  • Matt

    It IS about the CONTEXT.
    Ethan, Andrea & these guys are taking our side of the argument and driving it to the furthest illogical wall of the apposing corner in order to bolster their own position. Did anyone here ever give any disregard to due diligence, learning principles and getting reference and consultation or feedback?… NOPE. But reading their responses in isolation, apparently you would think we did. Don’t be so inane you guys.

    We’re not decrying these things, we’re simply decrying a lack of reasonable balance when we see a full promotional studio featurette spouting in-depth physics analysis and shot by shot assessments of character animation and we hear lines like, “‘Oh, I’m watching a cartoon.’ And that can really be damaging to the story.”… Really? Is that carved in stone above a door at Dreamworks somewhere? I sure HOPE not.

    When I wrote ‘DreamWorks Or BoringWorks’, perhaps I should’ve more clearly emphasised the DREAM part of the studios name. I WASN’T saying “dreamworks, yeah… more like boringworks, LOL” or anything even close to something like that. I was simply making a comment on the choice between Representation Vs Reproduction.
    Fair enough?

    • Ethan

      No. Not really.

      I don’t mean to give you a negative answer as in “no, not really, lol”, I should more clearly emphasize that what I mean is “I am the easter bunny”.

      • Ryan

        You see, this is what happens to the posts on CB.
        They attract incessant trolls like these here. ;)

        It is about Representation Vs Reproduction, that is a fair comment Ethan. You’ve made your point and now he’s made his. Don’t be the bitter antagonist here.

      • Ethan

        I’m sorry that you don’t appreciate my sense of humor, I’ll try to answer more seriously. What I meant by “I am the easter bunny” was this:

        They explain very clearly in the video that the goal is to help animator get a better “intuitive feel” of physics in general, it’s not about reproduction. It’s helping students to understand and follow consistently the established physics in a big project, even if the physics they settled on are totally wacky. The audience will adapt and accept how much you stretch the physics intuitively in that world, stretch as much as you want. But if you break those rules that you established yourself in your imaginary world, you’ll risk loosing the audience. To understand, establish, discuss, and avoid breaking the rules of that world, you need to understand physics in general. It’s only about making things “feel plausible”, it can be as wacky as you want.

        In both scenes where they fall to their death in HTTYD, the story would have been damaged had the scenes felt cartoony. It’s exactly that shot they are showing in the video when he says that. Look at all the praises for those shots, nobody thought it was “boring” quite the opposite, you can feel the struggle of the creature against an invisible enemy. It’s some amazing animation.

      • Ryan


      • Ethan

        That was terse… You ARE going to tell us your opinion about the subject, won’t you?

        You wouldn’t want anyone to think the only reason you posted here was to call someone a troll and a bitter antagonist. I’m sure somewhere inside, you have something to say, a passionate opinion ;)

  • Paul N

    I’ve chatted with Alej many times and he’s presented to at least one of my classes. To those that are bitching about his work, I can tell you from personal experience that he’s focused on all the things that any good animator should be focused on, and his presentations are entertaining, funny, and full of excellent examples of how to apply physics concepts in a cartoon environment. So lighten up already! :0)

  • Inkan1969

    Oh, wow. I’m a physics teacher at a community college. I would LOVE to have a job like Prof. Garcia’s.

    • But you can inject some enthusiasm into your own job by collaborating with animators at your university. Use animation to explain physics. Not only would it inject some fun into your job, it will bring some excitement to your curriculum and engage your students as well.

      • That’s right! Dave Chai and I wrote an article, which will appear later this year in “The Physics Teacher”, describing how animation teachers and physics teachers can come together. You can read the article here:

      • That’s great! Animation is now prevalent across college curriculum’s through out the world. But there are only so many openings at the studios (big and small).

        Being able to create a film for other industries, besides entertainment, is an aspiring goal for any independent animator. And its a great opportunity to have creative control over your own project and help a good cause of your choosing.

  • Dats All Folks

    Dreamworks problem isn’t physics…. ITs unappealing characters, and uninteresting stories.

    Can they get somebody to come in there and teach them that perhaps?

    • The problem with your criticism is that its subjective. Conversely, physics is objective.

    • Ethan

      Comment removed by editors. This is your 12th comment on a single post. Per our commenting guidelines, “A half-dozen comments on a single topic are unnecessary. Think about what you want to say and say it once. You can influence a discussion by the quality of your writing, not by how many times you repeat yourself.”