Here is one trick that I have seen done. Take a digital camera, mount it on a tripod with a radio remote. Using a spirit level, level the camera and lock it down. Set the camera to a “normal” f-stop, neither zoomed-in nor wide angle. If it has the ability to add a frame-number and time to each shot, turn it on.
If you need more than one camera to capture the motion without moving any of the cameras, do so. You want to capture with cameras locked in every dimension. Write down every one of the parameters: f-stop, ISO, everything. Write it on a board and photograph it at the start of every memory card, including the camera number.
(If you want to capture “camera moves,” that’s a lot harder to deal with, and you still need the others … the so-called witness cameras, whose purpose is to locate everything in 3D space.)
Now, work on a room or floor that has some kind of square pattern to it, of known dimensions. Be sure you can see the pattern in the camera. As you go through the moves, have someone with a roll of bright blue painter’s masking-tape put small reference marks on the floor (while dodging you). If your foot “hits a certain mark,” put tape there. (Better yet, number it.)
When you have a move worked out, hold the digital camera on rapid-fire (know the frame rate), or squeeze it by hand at one-second intervals. (Can you put a big digital clock with a seconds-counter somewhere in the picture? How about a sports timer, like they use at marathon races? Can you rent one for a day… leave it running? Does the coach at your school have one?) Objective data.
Now, with a notebook and a tape measure and a compass, measure everything. What is the exact distance from the camera to the various marks. What is the angle from the mark to the camera. Plot it all out on graph-paper (with a pencil) before you leave or tear-down. Measure everyone’s height, the length of their arms, and the distance from belt-line to floor. Lightly snap a chalk-line from the camera position to each wall… measuring for accuracy. Take measures from each line. Use a carpenter’s square. Use a thirty foot roll tape, not a twelve-foot pocket tape.
If you can, put a voice-recorder in the corner of the room or carry several of them around. Turn 'em on and leave 'em on. As you make a measure, say it out loud. As the performers move, they say, “one … two … three … turn … pause … pause … pivot …” Out loud.
In this way, you are building up factual data about the performance that you can translate directly to 3D, both in terms of space and time. It isn’t “motion capture” but it’s motion based.
Now … I can’t draw. Wish I could. Absolutely can’t. But you can take this and work out the moves… even if the actors consist of cylinders and cubes and spheres. You can also put it in proper scale. You ought to be able to set up a shot, superimpose the reference image as a backdrop, and it matches-up exactly. In a way that you absolutely cannot “eyeball.”
Further, this data can actually become an original source for the choreography that you work out later. “The foot hits the floor at 31 seconds, turns until 33, holds to 35, and at 36 lifts off…” This becomes fact. You will be quite surprised how different “what you thought you remembered” is from what the data actually tells you.
