User guide

Charnwood Dynamics Ltd. Coda cx1 User Guide – Coda Basics I - 1
CX1 USER GUIDE - COMPLETE.doc 26/04/04 34/162
In the Alignment dialog, there is a box in which to specify an ID name for the alignment
transform matrix. At present (May 2003), only one transform matrix may be stored, so this
box is disabled – the transform matrix is labelled ‘CodaAlignment’.
The alignment transform matrix is stored in the text file CXxxxx-Alignment.dat (where xxxx
is the Coda unit serial number) in the C:\Codamotion\Coda\ directory, and is loaded (only)
when Codamotion Analysis is started. If desired, you can place your own transformation
(rotation) matrix in this file. The matrix must be orthogonal – if not, Coda initialization will
fail with error 156.
Using an Alignment Transform
The use of a (stored) alignment transform when displaying or acquiring marker co-
ordinates is determined in the Acquisition Setup dialog by the Co-ordinate Transform
selection (CODA menu: Acquisition Setup… command).
After creating and storing an alignment transform, the Co-ordinate Transform selection is
automatically set to ‘CodaAlignment’.
To switch off co-ordinate transformation, select ‘none’ in the Co-ordinate Transform box.
If a co-ordinate transform is selected, it is listed in the message box which appears just
before data acquisition is started.
The Co-ordinate Transform selection (‘none’ or ‘CodaAlignment’) is saved with all other
acquisition options when the Setup is saved (Setup: Save Setup…)
If there is no stored alignment transform available, the Co-ordinate Transform selection
box will have only ‘none’ available.
When a co-ordinate transformation is in use, it (and the origin offset) is applied to the
Coda co-ordinates before they are stored after data acquisition. The stored data cannot
be de-transformed.
Remember that the transform matrix will be invalidated by moving Coda.
Aligning Two Codas
Two Codas may be aligned to each other and to a room (walkway) co-ordinate frame
either physically or by creating alignment transformation (rotation) matrices for each Coda.
If alignment transform matrices are created, they are stored in text files
C:\Codamotion\Coda\CXxxxx-Alignment.dat (where xxxx is the Coda unit serial number)
and can be used in subsequent measurement sessions if the Codas have not been
moved.
Physical alignment of two Codas is restricted to making them parallel or perpendicular to
each other, but with an arbitrary offset in all three directions. The field-of-views must
overlap at least at the point where a common origin is to be set (which must be the centre
of any force platform).