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24.2. Tracciamento live GPS
QGIS can help you do field mapping with a GPS receiver. Such a live tracking operation is done using the GPS Toolbar. Some device configuration may be needed before connecting QGIS and the GPS receiver.
24.2.1. GPS toolbar
The GPS Toolbar provides the main tools to control a live tracking session. It can be activated from . It follows the state of the project, GPS, and current GPS track, and enables actions only when they make sense. Once a device is detected by QGIS, you will be able to interact with it:
Recenter map on GPS location: the map will immediately recenter on the current GPS position regardless of the automatic recentering parameter.
Set destination layer for GPS digitized features: By default, QGIS will Follow active layer for feature digitizing, meaning that GPS digitizing tools will adapt to the layer selected in Layers panel and created features will be stored in it accordingly. While this may be useful in some contexts, it also implies careful interaction with other layers to avoid storing inadvertently features in undesired layers. This option allows you to explicitly indicate a layer for the data storage during the live tracking session, and you could switch depending on your needs. Exposed tools will adapt as well to the selected layer type.
The GPS destination layer is made automatically editable when a feature is being created, and the user is notified accordingly.
actions for feature creation:
Show GPS information: opens the GPS Information panel
a display box for quick access to some GPS information components you may need:
The Settings button opens a drop-down menu with common settings which are expected to be modified mid-session:
Options to control map recentering:
Automatically add track vertices whenever new locations are received from the GPS device.
Automatically save added features: features created from GPS locations are immediately committed to their target layers (skipping the usual layer edit buffer)
Time stamp destination to adjust the field for time fix storage
Log to GeoPackage/SpatiaLite…: When activated, the user will be prompted to select an existing GeoPackage/SpatiaLite file or enter a new file name. A
gps_points
andgps_tracks
table will be created in the file with a predefined structure.All incoming GPS messages will be logged to the
gps_points
layer, along with speed, bearing, altitude and accuracy information from the GPS.When the GPS is disconnected (or QGIS closed), the entire recorded GPS track will be added to the
gps_tracks
table (along with some calculated information like track length, start and end times).Log NMEA sentences…: enables logging all raw NMEA strings from the device to a text file
GPS settings… to access the GPS global options dialog
Suggerimento
Live status bar information on position
When a GPS device is connected and the user moves the cursor over the map canvas, a live status bar message displays the distance and bearing from the cursor to the GPS position. Project distance and bearing settings are respected in this display. On a touch screen device, use a tap-and-hold event to trigger the live status bar message.
24.2.2. GPS Information Panel
For full monitoring of a live GPS tracking in QGIS, you may need to enable the GPS Information Panel ( or press Ctrl+0).
In the top right corner of the GPS Information Panel, you press Connect to initiate connection between QGIS and a plugged-in GPS receiver, or Disconnect them.
In the top left of the panel, following buttons are accessible:
Settings: drop-down menu to live tracking options you may need to modify during a session
24.2.2.1. Posizione e attributi aggiuntivi
In the Position tab, if the GPS is receiving signals from satellites, you will see your position in latitude, longitude and altitude together with additional attributes.
Latitude
Longitude
Altitude (Geoid): Altitude/elevation above or below the mean sea level
Altitude (WGS 84 ellipsoid): Altitude/elevation above or below the WGS-84 Earth ellipsoid
Geoidal separation: Difference between the WGS-84 Earth ellipsoid and mean sea level (geoid),
-
means mean sea level is below ellipsoidTime of fix
Speed: Ground speed
Direction: Bearing measured in degrees clockwise from true north to the direction of travel
HDOP: Horizontal dilution of precision
VDOP: Vertical dilution of precision
PDOP: Dilution of precision
H accuracy: Horizontal accuracy in meters
V accuracy: Vertical accuracy in meters
3D accuracy: 3D Root Mean Square (RMS) in meters
Mode: GPS receiver configuration 2D/3D mode, can be
automatic
ormanual
Dimensions: Position fix dimension, can be
2D
,3D
orNo fix
Quality: Positioning quality indicator
Status: Position fix status, can be
Valid
orInvalid
Satellites: Count of satellites used in obtaining the fix
Total track length: Total distance of current GPS track
Distance from start of track: Direct distance from first vertex in current GPS track to latest vertex
24.2.2.2. Signal
With Signal tab, you can see the signal strength of the satellites you are receiving signals from.
24.2.3. Connessione di un GPS Bluetooth GPS per tracciamento live
Con QGIS puoi collegare un GPS Bluetooth per la raccolta di dati. Per eseguire questa operazione è necessario che il GPS sia dotato di Bluetooth e che il tuo computer abbia il Bluetooth.
Per prima cosa devi fare in modo che il tuo dispositivo GPS sia riconosciuto e associato al computer. Accendi il GPS, vai sull’icona Bluetooth nell’area di notifica e cerca per Nuovo Dispositivo.
Sul lato destro della maschera di selezione dei dispositivi assicurati che tutti i dispositivi siano selezionati in modo che probabilmente la tua unità GPS appaia tra quelle disponibili. Nella fase successiva dovrebbe essere disponibile un servizio di connessione seriale, selezionarlo e fai clic sul pulsante Configura.
Ricorda il numero della porta COM assegnata alla connessione GPS risultante dalle proprietà Bluetooth.
Dopo che il GPS è stato riconosciuto, esegui l’accoppiamento per la connessione. Di solito il codice di autorizzazione è 0000
.
Ora apri il pannello Informazioni sul GPS e passa alla schermata opzioni GPS. Seleziona la porta COM assegnata alla connessione GPS e fai clic sul pulsante Connetti. Dopo un po” di tempo dovrebbe apparire un cursore che indica la tua posizione.
Se QGIS non è in grado di ricevere dati GPS, devi riavviare il dispositivo GPS, attendere 5-10 secondi e tentare nuovamente di collegarti. Solitamente questa soluzione funziona. Se ricevi ancora un errore di connessione accertati di non avere un altro ricevitore Bluetooth vicino a te, accoppiato con la stessa unità GPS.
24.2.4. Examples of GPS devices connection in QGIS
24.2.4.1. Usare GPSMAP 60cs
MS Windows
Il modo più semplice per farlo funzionare è usare un middleware (freeware, non open) chiamato GPSGate.
Launch the program, make it scan for GPS devices (works for both USB and BT ones) and then in QGIS:
Ubuntu/Mint GNU/Linux
Per quanto riguarda Windows, il modo più semplice è utilizzare un server, in questo caso GPSD, quindi
Install the program
sudo apt install gpsd
Quindi carica il modulo del kernel
garmin_gps
sudo modprobe garmin_gps
And then connect the unit and check with
dmesg
the actual device being used by the unit, for example/dev/ttyUSB0
.Now you can launch gpsd
gpsd /dev/ttyUSB0
E infine connettiti con lo strumento di tracciamento live di QGIS.
24.2.4.2. Usare BTGP-38KM datalogger (solo Bluetooth)
Usare GPSD (in ambiente Linux) o GPSGate (in ambiente Windows) è semplice.
24.2.4.3. Usare BlueMax GPS-4044 datalogger (sia BT che USB)
MS Windows
The live tracking works for both USB and BT modes, by using GPSGate or even without it, just use the Autodetect mode, or point the tool to the right port.
Ubuntu/Mint GNU/Linux
Per USB
Il live tracking funziona anche con GPSD
gpsd /dev/ttyACM3
o senza di esso, connettendo lo strumento live tracking di QGIS direttamente al device (vedi esempio al seguente link /dev/ttyACM3
).
Per Bluetooth
Il live tracking funziona anche con GPSD
gpsd /dev/rfcomm0
o senza di esso, connettendo lo strumento live tracking di QGIS direttamente al device (vedi esempio al seguente link /dev/rfcomm0
).