Volker Franz, University of Tübingen, Germany
The Optotrak Certus and the older Optotrak 3020
(Northern Digital Inc.) are widely
used and highly accurate 3D motion and position measurement
systems. Traditionally, they are controlled using an interface written
in the C-programming language (the C-API you need to have purchased
from
Northern Digital Inc.). In
2004, I wrote a toolbox which allows to control the Optotrak from
within
Matlab.
This has a number of advantages: (a)
Matlab provides a flexible
environment for high level mathematics, much more versatile than
C. This is advantageous for the processing of the 3D data produced by
the Optotrak. (b) There exist already a number of
Matlab toolboxes for
psychophysical experiments. Most importantly the
Psychophysics Toolbox (mainly for
stimulus presentation) and the
Eyelink Toolbox
(controlling the SR-Research Eyelink Eyetracker). The Optotrak Toolbox
can be used to integrate the Optotrak with these other research
tools. Technically, the Optotrak Toolbox communicates with the
Optotrak from within Matlab by using
Northern Digital's C-API to
compile
Matlab
MEX-files.
The Optotrak Toolbox is currently tested under Windows 10, Windows 7, Windows XP,
and Linux (
Northern
Digital's C-API doesn't support Mac OSX, therefore the Optotrak
Toolbox also is not able to do so).
Sample programs
Here, you can find some sample
programs for the Optotrak Toolbox: Each sample is a 1-to-1 translation
of one of the sample C-programs which are shipped with the Optotrak
API
Download
If you are interested in the Optotrak Toolbox, I will be happy to send
you a copy by
email
(the Optotrak Toolbox is open software under the GNU general public
license, such that it is free and you can modify the source code if
you wish). Currently, the Optotrak Toolbox does not fully implement
all features of
Northern
Digital's C-API but it is used successfully by many labs around
the world (including my own lab where we have used it since 2004 with
many different versions of Matlab on Windows and Linux and with both,
the Optotrak 3020 and the Optotrak Certus).
Note, however, that I
cannot and will not provide support for it. The prerequisites to
use it on your side are:
- Northern Digital's
Optotrak Certus or Optotrak 3020.
- Northern Digital's C-API
(you need to have purchased this in addition to the Optotrak)
- Windows or Linux (better tested on Windows).
- A C-compiler (Northern
Digital's C-API works best with Microsoft's Visual C++ Compiler
which is nowadays freely available)
- ... and of course Matlab. Currently (i.e., as of 2021): This
could be either a 64-bit or a 32-bit version of Matlab (but make
sure you have the corresponding 64 or 32-bit version of
Northern Digital's C-API).
- You can compile the OptotrakToolbox from within Matlab and do
not necessarily need to first compile the C-API's sample programs in
C. However, in case you run into problems, I advice you to check
whether you are able to compile the native C-API's sample programs
in C. Many (if not most) problems arise at this level and not at the
level of the OptotrakToolbox. This compilation can be awkward and
you might need once a C-savvy person...
It is free, but consider citing it!
If you use the Optotrak Toolbox for a scientific paper, please
consider citing it. For example like this:
Movement recording was controlled with the Optotrak Toolbox by
V. H. Franz
(http://www.ecogsci.cs.uni-tuebingen.de/OptotrakToolbox) within
Matlab (Mathworks, Natick, MA, USA).
