This manual compass measurement only affects the output on this screen. It is not necessary for the
orientation data measured during scanning. During scanning, an orientation measurement is automatically
performed.
The accuracy of compass measurements can be affected by environmental interference, such as magnetic
interference. An indicator of the strength of environmental interference, and thus of the current compass
measurement accuracy, is the displayed
Horizontal field strength
of the magnetic field. The typical
strength of the earth's magnetic field depends on geographical position and varies from 0.3 to 0.6 gauss
(G). The displayed horizontal field strength is lower than the absolute field strength because of the
inclination of the field. For example, the typical horizontal field strength for Europe is about 0.2 gauss.
If the measured field strength differs significantly from the expected field strength, there might be a
strong, artificial magnetic field near the scanner that is affecting the measurement. To get the most
reliable orientation data for the scan registration, avoid positioning the scanner near strong magnetic
fields. If the measured horizontal field still significantly differs, switch the compass data to OFF.
NOTE:
Ferromagnetic objects (such as radiators and steel pillars) and electromagnetic fields (e.g., from
electrical cabinets or controller units) can disturb the earth magnetic field. This, as well as local
variations in earth magnetic field (magnetic declination/variation) can lead to inaccurate
compass measurements. In this case it’s recommended to switch off the use of the compass data.
GPS
The scanner's position information provided by the built-in GPS sensor is attached to each scan, and is
used for the scan registration in SCENE, if the GPS sensor is switched ON.
Use GPS
- Turn the GPS sensor ON or OFF. Unlike the other sensors, GPS data is only recorded and
attached to each scan, if this sensor is turned ON. For more information, see
After the GPS sensor is switched ON, it begins searching for GPS satellites. Note that it can take a few
minutes to find all available satellites, and to determine precise positional information. We recommended
switching the GPS sensor OFF, if it is not needed or if a GPS signal is not available (e.g., if you are
scanning indoors).
GPS information
- Provides information about the currently measured GPS coordinates, including the
latitude, longitude, and altitude, as well as the UTC time of the last satellite contact and the number of
satellites that are currently in view. The GPS receiver needs the signal of at least three satellites to
calculate a 2D position (latitude and longitude). With four or more satellites in view, the receiver can
determine the scanner’s 3D position (latitude, longitude, and altitude).
The signal strength bars below the GPS information appear for each satellite in view with the appropriate
satellite number underneath. These indicate the signal strength for each satellite.
GPS precision
- Provides information about the precision of the currently measured coordinates in meters
or feet. The DOP (dilution of precision) values are an indicator of the current satellite constellation
geometry's quality. In general, good position measurements can be achieved, when the satellites are
located at wide angles relative to each other. In this case, the DOP values are low. Higher DOP values
indicate a poor satellite geometry, which might have a negative effect on the position accuracy.
FARO
®
Focus Premium Laser Scanner User Manual
Chapter 6: Controller Software
FARO Focus Premium (March 2022)
Page 84 of 157
