User guide

Charnwood Dynamics Ltd. Coda cx1 User Guide – Coda Basics I - 1
CX1 USER GUIDE - COMPLETE.doc 26/04/04
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on the walkway in front of Coda (two on the x-axis and one on the y-axis), and observe
their co-ordinates with the real-time co-ordinate display (CODA: Display Marker
Positions…). Rotate Coda about a vertical axis to equalize the y-co-ordinates of the x-
axis markers, and adjust Coda’s feet to equalize the z-co-ordinates of all markers. Reset
the marker origin periodically to facilitate comparison of the co-ordinates.
Creating an Alignment Transform
This allows the Coda to be used in an arbitrary (fixed) orientation to the room (walkway)
co-ordinates:
By placing markers in the field of view which define the room X-axis and Y or Z axis, an
alignment transformation (rotation) matrix can be created and stored which can be applied
to all subsequent measurements:
Place one marker at your origin, and another at a point on your new X-axis at least
500mm away from the origin in the positive direction. A third marker may be placed on
the negative X-axis (at least 500mm from the origin) to improve the accuracy of the
alignment.
Place another marker at a point on one of your lateral axes (Y or Z), at least 500mm away
from the origin in the positive direction. In conjunction with the X-axis markers, this
marker is used to define the principal plane of your co-ordinate system (the X-Y plane or
X-Z plane), but does not have to be placed exactly on the lateral axis, as this axis will be
made orthogonal to the X-axis automatically. Another marker may be placed in the
principal plane near the negative lateral axis (at least 500mm from the origin) to improve
the accuracy of the principal plane.
It is not necessary to mark the third axis, as this is automatically generated as a line
through the origin perpendicular to the principal plane, in a direction which defines a right-
handed co-ordinate system.
All markers should be placed facing Coda, and there should be no reflecting surfaces
nearby.
Open the Align Coda Co-ordinates dialog by selecting the Align Coda… command on
the CODA menu, and enter the marker numbers in the appropriate boxes. If you have
used only two markers per axis, then enter the origin marker as the first (‘-‘) marker for
each axis.
Press OK to generate and store an alignment transform matrix.
If the marker positions are inconsistent, an error message will be given.
When placing the marker(s) to define the lateral axis, be sure to place it on the correct
side of the origin so as to define the third axis in the required direction. If you stand facing
along the positive X-axis and place the Y-axis marker on your left, the Z-axis will be
positive upwards to give a right-handed co-ordinate frame. (If the lateral axis marker
defines the Z-axis and is on your left, then the Y-axis will be positive downwards.)