Motion Capture Workflow
		Motion Capture  ·  What is it?  ·  Why use it?  ·  Recording vs. real-time  ·  Magnetic ·  Optical ·  Electro-mechanical  ·  Workflow  ·  Specialized tools ·  Who uses it?	Products  ·  Motion Captor  ·  Gypsy  ·  Datagloves  ·  Cybergloves  ·  Face Trackers  ·  MotionBuilder

Motion capture involves recording rotation or position of joint sensors on a performers body. This information can be recorded frame-by-frame and subsequently applied to a character's skeleton (post-processing). In the case of real-time performance animation, the motion capture data drives an intermediary skeleton that in turn drives a 3D character's skeleton.

In the case of post-production, multiple takes can be combined, along with animation generated 'by hand' to get just the right effect. In the case of performance animation, macro's may be used for certain character moves or real-time changes in camera angle/position or background and set items, but the live nature of the performance limits the amount of adjustments or operator changes to the motion that can be done during the performance.

In either of the above cases, recording motion accurately can be very challenging.

Marker offsets
In the cases of magnetic and optical systems, markers are offset from the actual joints being measured, therefore inverse kinematics (IK) is required to derive the performer's actual joint angles from the marker rotations / positions.

Massive amounts of data, frame by frame
Motion capture generates one keyframe per frame for every joint / body part that is being measured. Before specialized tools for keyframe reduction / generalization and clean-up were available, the massive amount of data generated by motion capture takes often discouraged would-be users of motion capture. (Editing every single frame of a motion capture take often took as long as animating the sequence by hand.)

Differences in dimensions / body type between performers and characters
Motion capture generally needs to be adapted to work successfully on characters of different proportions / sizes than the original performer, otherwise hands and feet may not meet intended objects / positions in the environment, or body parts may interpenetrate. It is always a good idea to 'mock-up' the performer to simulate the character; i.e., if the character has a big stomach, it is good to attach pillows to the performer to help avoid the character's arms going through its stomach.