User manual
Version: v4.5.2
8.2.1 Recalibration of a marker
In order to get even more accurate measurements, the
markers
can be calibrated each time the reflecting
fiducials
are mounted / dismounted. The demo application allows the user to perform this operation. This
operation requires that only the
marker
to recalibrate is seen by the fusionTrack (and the corresponding
geometry must be activated), it also requires the temperature of the device to be stable, i.e. the device must
be running for some time. The procedure records the
fiducial
positions for a maximum of 10,000 frames
and creates a new geometry file, which is saved automatically and can be opened directly from the demo
application. It also will be automatically added to the list of known geometries and read at the next start of
the demo application. The old geometry is automatically disabled and the new one enabled. The produced
file is stored in a user-specific location (
%APPDATA%\Atracsys\PassiveTrackingSDK
on Windows).
The recalibration algorithm can reassign fiducial IDs, i.e. fiducial 0 from the old geometry might become
fiducial 2 in the new one. This is done such that similar geometries have similar geometry files. The choice
is based on distances to choose fiducials 0, 1 and 2. The first three fiducials are always coplanar.
8.2.2 Exporting the data
The demo program allows to export the received data in CSV format
. The dedicated panel ‘Data export’
allows to chose the exported data and the number of saved frames. The export consists of up to three files,
respectively containing:
1. the
raw data
;
2. the 3D
fiducial
data;
3. the
marker
data;
4. the temperature data.
It must be noted that the ‘demo.exe’ software acquires data from the fusionTrack at the display update rate.
This means that exported values won’t be recorded at the maximum speed of the fusionTrack. The user
can choose which data to export (the default setting is to export everything, i.e. to create three files). The
number of frames to record can be set, in which case the saving will automatically stop when this number
is reached, or let free. In the latter case, the user will need to stop the recording manually. In order to
ensure compatibility, a version of the export can be set, which garantees that a reading application will be
able to read the data created by a newer version of the application. The separator used in the CSV files is
the semi-colon (‘;’), to comply with systems using a comma as decimal mark. The saved information is the
same as contained in the
ftkRawData
,
ftk3DFiducial
and
ftkMarker
structures. The written information
for
raw data
is the timestamp (in hexadecimal), ‘left’ or ‘right’ as an indication of the camera, the index of the
raw data
, the 2D coordinates of the
raw data
, its surface, probability and status, as presented in Listing 8.1.
1
timestamp ;left/right ; index ;x;y; surface ; probability ; status
Listing 8.1: Structure of a line of the raw data export CSV file.
The written information for
fiducials
is the timestamp (in hexadecimal), the index of the
fiducial
, its 3D position,
the values of the epipolar and triangulation errors, its probability and the indices of the used left and right
raw data
s, as presented on Listing 8.2.
10
A comma-separated values (CSV) file stores tabular data (numbers and text) in plain text. Plain text means that the file is
interpreted as a sequence of characters, so that it is human-readable with a standard text editor. Each line of the file is a data
record. Each record consists of one or more fields, separated by commas.
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