The Art and Soul of Motion Capture

deemarie · April 11, 2005 3:10 pm

Love it, hate it, or just plain dont understand it. Any way that you look at it, motion capture has become a valuable tool in the animators arsenal. It has been used in a number of award-winning, top grossing feature films and is used extensively for character animation in video games. Even though a lot of videographers and digital artists have a solid understanding of building 3D into a production pipeline, motion capture still remains something of an enigma. Most people now understand the basics of motion capture, even if only from watching the special feature section of Lord of the Rings. The next step in the demystification is getting motion capture samples and tutorials to talented digital artists and animators. This objective comes with its own set of challenges and problems. There are several myths that have developed regarding motion capture among the traditional animators, who are the most reluctant to try the technology. One of the basic questions looming in many minds is What exactly is motion capture and what can it do for me? Motion capture is the easiest, and often the most cost-effective alternative for computer-animation of people, animals, or creatures that require realistic or life-like movement. It is, essentially, the process of capturing the movement. That motion is brought into a number of animation packages and applied to a 3D model or character. One common argument that we hear from animators is that motion capture is too limiting and too expensive. Motion capture is neither but you need to be clear about what you are capturing and why you are doing it. The act of capturing the gross motor movements of a character, especially one that is remotely human, will reduce an animators production time significantly. There are millions of visual cues, postures and physical nuances that we use to communicate which are simply too complex and/or time consuming for keyframe animation. Motion capture can translate those cues to the character and allow the animator to start from a solid working base. A myth that we try very hard to dispel is that motion capture will eliminate or replace key-frame animators. Lets make one thing clear: motion capture does not replace a talented animator; in fact, the very best effects have resulted from a combination of motion capture and key-frame animation techniques. Capturing the performers human motions is only one step in the animation process. Animators can then exaggerate certain characteristics, gestures and nuances to end up with their characters final performance.
As well as providing character animation data, motion capture studios provide a broad range of other valuable offerings. Imagine being a director with a complex 3D scene and character. Now place yourself in a studio where you could, with the aid of a pair of virtual reality goggles, walk through your scene with your characters and plan your camera moves and triggering sequences while the character and scenery is rendered in real time. Storyboards spring to life because the animators create their animatics in real time utilizing motion capture data. And last, but surely not least, watch your character animated in real time while directing the actor gives the animators and director invaluable information. The director now instructs the actor how to alter his performance to compensate for any distinctive character traits the model may have; for example, much longer legs or arms, bigger head, etc. Planning Is The Key I am not touting motion capture as the answer to all animation issues (well, maybe I am but that would be another story), however, planning is the key to achieving your goals from a motion capture session. Some examples of planning: 1. Identify what/who you would like to capture; male, female, are there any special characteristics that you require? Choose your actors well; a 6 foot 5 inch, 200 lb. male kick boxer will have a distinctly different set of moves from a 5 foot 5 inch 110 lb. female ballerina (yes, even just walking). 2. Prepare a shot list, including the detail. Get shot will probably not be enough direction to an actor. You may wish to elaborate: shot on the left side of the head, fall to the right sideways gives your actor a little more to work with and you have a better chance of getting what you want. 3.Identify any props that you will require (guns, walls, pads, etc.). Most props will be supplied by the studio but make sure and identify any props that you wish to capture the motion of, it does happen. We have been asked to capture swords, guns, and all sorts of things. 4. Have at least one rehearsal with your actor if possible. Establish communication with your actor and set their expectations. This will make your motion capture session much more efficient. 5. Run some range of motion tests with your models and rigs. Do you have any mesh or skeleton issues? Most motion capture houses will help you test your assets. A select few will also let you view the motion on your character in real time during the capture day so that you and your actor can make allowances for any differences in physical proportions that may exist (i.e., longer than normal legs or arms). Never fear, most studios will work closely with animators that have no prior motion capture experience. This helps both parties to understand what is going to be accomplished, dispels any pervading myths, and ensures that everyone ends up having a great experience. Are you still unsure? There are also a number of places to get sample motion files. My suggestion is to get data, read tutorials, and ask questions. Many motion capture studios are happy to answer your questions and help allay your fears about their product. Message2209424.jpgAbout Mantis Motion Productions Located in Utah, our studio offers a unique alternative to traditional motion capture studios. We are an energetic, experienced team of people dedicated to deliver very high quality animation and data. Our mission is to deliver the best possible solution in the minimum amount of time. We supply the highest quality data and animation for games, television, music videos and film productions. The flexibility of our motion capture solution easily accommodates the fast paced environment of episodic television shows, and can shave days or weeks off of game and film productions. We can provide the data captured in numerous formats whether you require skeletal data or simply marker translational data for integration into your 3D animations. We have the ability to deliver data in many 3D motion formats and for any technical pipeline. Once the data is captured and processed, we also provide an array of services to ease the integration of the motion captured animations into your pipelines. Our studio employs leading edge technology that enables us to generate data with minimal occlusion Add to this equation our vastly reduced set up times and this allows our customers to spend more time capturing motion rather than fixing issues in the data captured, making us a very cost effective solution for any sized project. We welcome you to visit Mantis Motion Productions for additional information.
The Art and Soul of Motion Capture first appeared in Issue 7 of the Renderosity Magazine

Article Comments

nemirc ( posted at 12:00AM Wed, 13 April 2005

I hadn't seen this one for a long time. It's good to see it around :)

Santel ( posted at 12:00AM Thu, 14 April 2005

Fascinating info...but the link dosen't work!

deemarie ( posted at 12:00AM Thu, 14 April 2005

Hi Beachadonis, thanks so much for the great comments - Mantis Motion had a slight change to their web site URL - Thanks for the heads-up, the link should work fine now :)

tufif ( posted at 12:00AM Thu, 14 April 2005

Great info! One day I'll have the budget to use motion capture. Until then I'll have to get by with my trusty webcam.

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