Art Flystick2 - Body Calibration; Definition of the Coordinates by the Body Itself; Definition of the Coordinates by the Room Coordinate System, with Origin in the Center of the Markers; Definition of the Coordinates by the Room Coordinate System, with Origin in a Marker

Appendix B
B.1 Definition of Coordinates and Rotations
B.1.2 Body Calibration
During the body calibration DTrack2 is fixing a local coordinate system (body coordinate
system) for each rigid body. Both coordinate systems define the later 6DOF output (see
chapter B.1.3 on page 252). The calibration can be done in three different ways (to be
selected in the menu Calibrate / Body of the body calibration):
B.1.2.1 Definition of the Coordinates by the Body itself
Body calibration setting due to body:
The body coordinate system is fixed by the markers of the rigid body according to a set
of rules:
1. Search the biggest distance between two markers of the rigid body. These two
markers (#1 and #2) will define the X axis.
2. Search for a third marker (#3) that has the smallest distance to one of the two
markers #1 and #2. The marker that has smallest distance to marker #3 becomes
marker #1. It will define the coordinate origin. The other marker will be #2. The
positive X axis is directed from marker #1 to marker #2.
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.
B.1.2.2 Definition of the Coordinates by the Room Coordinate System, with Origin
in the Center of the Markers
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 position 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.
B.1.2.3 Definition of the Coordinates by the Room Coordinate System, with Origin
in a Marker
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
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