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Lise Worthen
03-08-2000, 06:46 PM
Dear Colleagues

We are currently using a VICON Motion Analysis system for 3D movement
analysis in conjunction with BodyBuilder analysis software (Oxford
Metrics). Amongst other things we are employing a Butterworth filter for
data smoothing, but are experiencing problems trying to implement this
within the BodyBuilder programming environment. The writing of the filter
itself is straight forward enough, however we are experiencing difficulties
with the implementation of a reverse pass for the filter.

Our questions are as follows:

1) Has anyone had similar experiences with programming and writing code
within the BodyBuilder package. Apparently, BodyBuilder is
based on C++, however certain conditional statements written in this code
appear unsupported (as do Basic and Fortran type commands).

2) Is there any programmers reference documentation available for
BodyBuilder (apart from the official manuals) listing commands and functions

3) does anyone know a function word (like step -1) or a solution for driving
the iteration backward in bodylanguage?

Finally - in relation to filters in general -VICON (who have been very
supportive) recommend using a MSE of 20 when employing a Woltring type
filter - having reviewed appropriate literature we can find no reference for
the relevance of this value.

Kind Regards

Jon Spriggs
Biomedical Engineer
Soar Research @ LIU
&
Lise Worthen
Biomechanist and Lab Coordinator
Soar Research @ LIU
122 Ashland Place #1A
Brooklyn, NY 11201
718-246-6378
718-246-6383 fax
lworthen@liu.edu

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