Motion Capturing Device

[danylyon]

But if I understand the whole principle. Captors are being used to "mesure" muscle mouvements (muscle mouvement = electric shocks and those are captured by the captors) this being "translated" from raw data to something that is made in to mouvement and the mouvement is being filmed by a camera and both are being transposed.

As far as I know, it doesn't work like that.

Simple example. Take a black rod. put two white dot's on each end. Film it with a camera, while you move it. Track both points with an ordinary compositing app (like combustion / After Effects). and you've got a 2 Dimensional Direction of that rod, an angle.

Now, film same rod with two (or more) cameras (at the same time, from different positions).. track the two points in each camera.. combine them (this is where proprietary software comes in) and you've got it motion tracked in 3D Space.

Now the same with the suit... and you can imagine that you need a lot of propriatary software, maybe even special cameras etc. to keep track and combine all those points.

You might also want to check out: http://www.ssontech.com
It's for 3D Tracking a scene, but I think it can do more.. but I haven't looked into it any more yet.

[TheCaveman]

I agree with the software but imagine this would be possible to write (would take some time to adjust and to find the correct algorithms I think(I don't think but I'm pretty sure hehe), but with C++ and Cg (opengl or something) it should be possible to write (they already done it). what else would be needed to do so? what kind of captors? would it just be light points or cables sending directly information to a computer who analyses everything? I remember when I saw some motion capturing making offs they were completly wired:

http://www.measurand.com/products/ShapeHand.html

But if I understood your link the thing they are talking about is shooting "real" environnements and paste these into your animation your are doing in 3D. Like place a real environnement around a 3D object
for filming an environnement and place it into 3D would even be harder hehe.

was talking about this:

The Gypsy is a patented electro-mechanical system consisting of an exoskeleton made of lightweight aluminum rods that follow the motion of the performer's bones. Potentiometers (variable resistors) at the joints change voltage (varying resistance) based upon angular rotation of the rods. A gyroscope (mounted in the hip piece) is used to calculate the bearing (rotational direction) of the hips.

Gypsy Gyro uses small solid-state inertial sensors ('gyros') attached to the body to measure the motions of the actor's skeleton. How it works
In Gypsy 4 and Gypsy Torso, An AtoD (Analog to Digital converter) on the suit converts the analog voltage changes from the suit's various potentiometers to digital values. These digital values are transmitted to the computer where the driver software interprets this information (based upon the performer's calibration file). The data drives a skeletal representation of the performer's skeleton in real-time, in response to the performer's motions. The software can sense which foot is placed where on the ground, and it calculates footstep placement accordingly. The gyroscope's readings of hip bearing describes movement of the performer's center of mass. The result is relative variations from initialization position, which results in accurate global translations.

In the case of Gypsy Gyro, small gyroscopes attached to the actor's limbs or other body parts detect the exact motions of all the body parts to which they are attached. The angular changes are collected on the suit and transmitted to the capture computer in real-time. An optional 19th gyro can be used to track the movement of swords or implements.

Calibration
In the case of Gypsy 4 and Gypsy Torso, accurately recording of the rotation of Gypsy's exoskeleton wouldn't be very useful if it weren't for the Gypsy's Inner Skeleton calculation. This Human Calibration™ involves measuring distances between joints, and offsets from the rotational centers of the potentiometers to the center of the joints. The result is highly accurate inner skeletal data, based upon virtual joints of the performer's skeleton.

An experienced Gypsy 4 operator can create a quick calibration file for a new performer in approximately 10 minutes. An accurate calibration file can take about 30 minutes. Calibration is even faster for performers of similar size and proportion to previously calibrated performers. Once calibrated, a periodic re-initialization (5 seconds or less) readies the Gypsy for accurate recording.

Gypsy Gyro works well without calibration, since the rotation of the actor's skeleton can be applied directly to the 3D character's skeleton. Accuracy can be increased by a simple process of measuring and entering the lengths of the various limbs into a calibration file..





apperently there are three differents ways of mocap : Magnetic (http://www.metamotion.com/motion-capture/magnetic-motion-capture-1.htm), optical and Electro-mechanical. (http://www.metamotion.com/motion-capture/electro-mechanical-motion-capture.htm)
what I posted above falls under electro mechanical

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