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Plenty of artists getting into the visual fx fields are not aware that the large studios have a “pipeline” of artists. These larger facilities, expect the artist to be specialized in a specific task, and it is only in the smaller studios that artists are expected to be generalists. (artists who are capable of wearing many hats). We get many questions from readers asking us to be a bit more descriptive of the positions that are found in the studios, so we took the opportunity to ask fellow artist Kevin Hoppe, to help us out on defining and explaining what his department is all about.

Kevin Hoppe is a Matchmove Supervisor / Maya Generalist. In addition to tracking, he programs custom tools, trains VFX artists, and serves as an all around 3D troubleshooting guru.

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What is Matchmoving?

Matchmoving is the name given to a number of different techniques used to bridge the gap between live action (what is filmed on set) and a 3D Animation Pipeline.

OK, so that was kind of vague and perhaps not that helpful. Here’s the plain English version.

If you want to add CG (computer generated) elements to a shot that you film you need to think like this… Presumably you want the end result to look like the CG element was there all along when you filmed originally. Because this was impossible, or too expensive you are now adding something digitally which is completely fine. But for your CG to look as realistic as possible the first step is to “film” it looking through the same camera and same lens that you used on set.

Of course you can not do this, but you can set up a camera in the 3D program you are working in that is set up with exactly the same lens, camera height, film back, same tilted funky angle or whatever…. the better you match it the better the cg will look. Of course there is a lot more to matchmoving,but the most basic idea is to make a camera in your cg package that matches exactly to your film, or digital camera you used on set.

What if we moved or tilted the camera during the shot we filmed?

Well then you are going to have to match no only the camera settings, but the camera movement too. This has to be done with great precision or your cg element will look like it is “sliding.” So in this case we have to track the movement of the camera. This sounds like a pain, and indeed it can be, but there are software programs out there to help. These programs (Boujou, Syntheyes, and 3D Equalizer) will help analyze the movement of the camera and generate a CG camera for you that matches the one you filmed with.

What about other objects that are in the scene?

You will need to build a simple version of anything your CG interacts with. So if you make a CG creature that crawls across the floor, you have to build a floor. If he jumps off a table, lands on a chair, and then hops down on the floor you have to build the table, the chair and the floor. These

objects will show your animators where everything is so they can properly animate. These objects will also be used in Lighting to catch shadows and such for realism.

How do you add an effect onto a person or a part of a person?

Well, this is a bigger issue, but like most shots that involve a mixture of real life and CG, the solution is rooted in good matchmoving… or in this case, match-animation. Let’s use “The Mist” as an example. In this movie the bag boy, “Norm”, has a big tentacle wrapped around his leg. To pull this off we had to track the camera in each shot and then track Norm’s leg. To do this we had our modeling department make us a 3D model of Norm, and our character rigging department rig it up so we could move it around. Since our camera is a perfect match to the original, and out model of Norm is (as close as possible) a perfect match to Norm we can lay him out on the floor and visually line him up our CG Norm to the actor. Then we animate Norm’s leg so it moves just like the actor’s leg. So now, instead of Norm’s leg getting pulled around by an imaginary tentacle (or in this case we
used a rubber one, or a rope) the CG Norm leg will be a place for our digital tentacle to wrap around. So it will then look like, with some good animation, the cg tentacle has got Norm.

So… the bottom line is… anything that films, interacts with, or is touched by you cg element has to be completely re-created in 3D. This is the job of the matchmover. It’s is a tough job, but someone has to do it.