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Document MV0319P.N

MVN User Manual

8.2 Calibration

Segment calibration is the step required to align the motion trackers to the segments of the subject.

Watch the video on the tutorial portal for instructions on how to perform the calibrations:

https://tutorial.xsens.com/video/setup-and-calibration-mvn-link.

Creating a good calibration is of utmost importance in order to ensure accurate results. For this reason,

the calibration procedure should be carried out in a magnetically-sound environment. The “Show

Magnetic Disturbance” is fixed at “Always on” when the calibration tab is active.

It is advised to check the measuring area for magnetic disturbances. To do this, move around the

measurement area. Areas which appear green, particularly on the feet and pelvis are good for the

calibration step. If measurements are needed in areas that reveal red in the magnetic field disturbance,

first calibrate in the “green” areas then move temporarily to the disturbed area. Do not remain there for

longer than approximately 30 seconds.

8.2.1 Calibration steps

Please note that it is always recommended that a calibration is performed before beginning to record

data using MVN Studio. However, it is possible to enable a measurement without calibration in the

preferences menu (Options >Preferences >General >Recordings).

Another option in the preferences menu is “Expert calibration” in this menu. Expert calibration is intended

for users who have been advised by specialists at Xsens to perform a hand-touch calibration in addition

to their N or T pose. However it becomes possible to execute both N and T- Pose by enabling this.

Carrying out both basic poses is strongly dissuaded. If both calibrations are carried out, a weighted

average of both will be used. This is known to lead to inaccuracies in the results.

 Select a pose (N or T).

 A new image will appear in the 3D viewport

which should be replicated by the subject.

 If the subject is alone, first select “Hands off

calibration” and the amount of time needed to

get into position. (See Section 8.2.5)

 Click “Calibrate”.

 Ensure that the subject is holding the pose.

 Click start.

 Under Messages for calibration: If the result is

“good”, click “accept”. If “acceptable”, it is the

user’s decision if they wish to improve this. If the

result is “Poor” it is advised that the calibration is

discarded and performed again following the

instructions provided in the Messages area. If

“Fail” results, the calibration must be repeated

before proceeding. (See Section 8.2.6 for more

information.)

Figure 34: Segment calibration interface – new

screenshot with no data fusion tab

Note that if multiple people will be measured simultaneously (multi-person capture), mark a place on the

floor which does not show magnetic disturbances. This will be the origin of the session. Each person

should stand on this spot with the right heel when performing the calibration poses.

The MVN system does not have an absolute positioning system. Therefore, the characters will show

some drift over time in terms of absolute position in space with respect to the origin (defined at