Glossary

Motion Capture

The recording of human and animal movement by any means. Today's modern motion capture is mainly recorded by either video, magnetic, or electro-mechanical devices.

Performance Capture

The recording of a performance, either human or animal, using a MOTION CAPTURE system (or similar technology) - difference being that you can motion capture a table, but it is cannot give a performance.

MoCap

MoCap = MOtion CAPture

Magnetic Motion Capture Systems

A magnetic field generator is set up in the room. MAGNETIC SENSORs are placed on the subject's body that each detect their individual position and orientation relative to the generator

Magnetic Sensor

Magnetic sensors are used in MAGNETIC systems. These are equivolent to a MARKER, but also able to detect orientation as well as position.

Marker

Markers are used in OPTICAL systems. They are either reflective "balls" in a PASSIVE system, or LEDs in an ACTIVE system, worn by the subject. It is the position of these markers that is recorded during motion capture.

Optical Motion Capture Systems

There are 2 types of optical motion capture systems:

Passive

An array of video cameras surround the subject to be recorded. Each camera has a ring of lights (LED's - Light Emitting Diodes) around the lens that send light towards the subject. This light bounces back off refective MARKERs that have been placed on the subject.

Each camera sees a different picture of the MARKERs since each camera is in a different position in the room. These pictures are used to work out the reletive poisition of each camera, and hence the real world 3D position of the MARKERs.

 

Active

Similary to PASSIVE, but instead of the camera LEDs sending light to bounce off the MARKERs, the MARKERs themselves are the LEDs and send light to sensors (cameras) in the room.