Chapter 8
8.6 Menu Calibration
3. Marker # 3 defines the X/Y plane, together with markers # 1 and # 2. Marker # 3
has a positive Y coordinate.
4. The Z axis is already defined by these rules, resulting in a right-handed coordinate
system.
(a) Body calibration
"due to body"
(b) Body calibration
"due to room"
(c) Body calibration
"due to room (zero in
marker)"
Figure 8.33: Defining the target coordinate system
Body calibration setting due to room The origin of the body coordinate system is set
to the center (center of gravity) of all markers building the rigid body. The axes of the body
coordinate system are parallel to the axes of the room coordinate system in the beginning
of the body calibration. I.e., the result of a body calibration will depend on the angular po-
sition of the target during calibration. A 6DOF measurement, following calibration without
having moved the body, will give the angular coordinates 0
◦
/ 0
◦
/ 0
◦
.
If the target was moved during calibration, the angular position of the target at the begin-
ning of the calibration will be taken.
Body calibration setting due to room (zero in marker) A combination of the first two
methods. The direction of the axes of the body coordinate system will be set parallel to
the room coordinate system in the moment of body calibration - like done with setting due
to room. The origin of the body coordinate system is given by one marker of the body,
according to the rules given for setting due to body.
8.6.5.5 Selecting the coordinate system for 5DOF targets
Analogue to the settings for the standard targets it is also necessary to define the body’s
coordinate system in case of 5DOF targets. For these bodies the rotation around the
body axis cannot be measured by the tracking system. Thus, the 5DOF central axis is
important if you intend to use the rotation around the body axis. The most important
properties are:
• If the 5DOF body is positioned parallel to the 5DOF central axis the rotation around
the body axis remains undetermined.
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