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24.2. ライブGPS追跡

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 View ► Toolbars ► GPS. 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:

  • gpsConnect Connect to GPS

  • gpsDisconnect Disconnect from GPS

  • recenter Recenter map on GPS location: the map will immediately recenter on the current GPS position regardless of the automatic recentering parameter.

  • gpsDestinationLayer 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:

    • addTrackPoint Add vertex to GPS track using GPS current location

    • capturePoint Create a new point feature at current GPS location

    • captureLine Create a new line feature using the current GPS track

    • capturePolygon Create a new polygon feature using the current GPS track

    • reset Reset track

  • metadata Show GPS information: opens the GPS Information panel

  • a display box for quick access to some GPS information components you may need:

    • unchecked Show location

    • unchecked Show altitude (Geoid)

    • unchecked Show altitude (WGS 84 ellipsoid)

    • unchecked Show ground speed

    • unchecked Show bearing

    • unchecked Show total track length

    • unchecked Show distance from start of track

  • The options Settings button opens a drop-down menu with common settings which are expected to be modified mid-session:

    • unchecked Show location marker

    • unchecked Show bearing line

    • unchecked Rotate map to match GPS direction

    • Options to control map recentering:

      • radioButtonOff Always recenter map when the GPS position is offset from the map canvas center by a certain distance (as a ratio of the map canvas extent)

      • radioButtonOn Recenter map when leaving extent

      • radioButtonOff Never recenter

    • unchecked Automatically add track vertices whenever new locations are received from the GPS device.

    • unchecked 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

    • unchecked 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 and gps_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).

    • unchecked Log NMEA sentences...: enables logging all raw NMEA strings from the device to a text file

    • options GPS settings... to access the GPS global options dialog

Tip

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 (View ► Panels ► 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:

  • metadata Position: live details on the GPS position and sensors

  • gpsTrackBarChart 信号: 衛星接続の信号強度

  • options Settings: drop-down menu to live tracking options you may need to modify during a session

24.2.2.1. 位置と追加属性

In the metadata Position tab, if the GPS is receiving signals from satellites, you will see your position in latitude, longitude and altitude together with additional attributes.

../../../_images/gpstrack_main.png

図 24.3 GPS追跡位置と追加属性

  • 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 ellipsoid

  • Time 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 or manual

  • Dimensions: Position fix dimension, can be 2D, 3D or No fix

  • Quality: Positioning quality indicator

  • Status: Position fix status, can be Valid or Invalid

  • 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 gpsTrackBarChart Signal tab, you can see the signal strength of the satellites you are receiving signals from.

../../../_images/gpstrack_strength.png

図 24.4 GPS追跡信号強度

24.2.3. ライブトラッキングのBluetooth GPS への接続

QGISを使用すると、フィールドデータ収集用のBluetooth GPSを接続できます。このタスクを実行するには、GPS、BluetoothデバイスとコンピュータのBluetooth受信機が必要です。

最初にあなたのGPSデバイスが認識され、コンピュータにペアリングさせる必要があります。 GPSをオンにし、あなたの通知領域にBluetoothアイコンに移動し、新しいデバイスを検索します。

デバイス選択マスクの右側で、すべてのデバイスが選択されていることを確認し、GPSユニットが利用可能なものの中に表示されるようにします。次のステップでは、シリアル接続サービスが利用できるはずなので、それを選択して Configure ボタンをクリックします。

Bluetoothの特性によって生じた、GPS接続に割り当てられたCOMポートの番号を覚えておいてください。

GPSが認識された後、接続のためのペアリングを行います。通常、認証コードは 0000 です。

次に GPS情報 パネルを開き、options GPSオプション画面に切り替えます。GPS接続に割り当てられたCOMポートを選択し、接続 をクリックします。しばらくすると、自分の位置を示すカーソルが表示されるはずです。

QGISがGPSデータを受信できない場合は、GPSデバイスを再起動して5〜10秒ほど待ってから、再度接続を試みてください。通常、このソリューションで対応できます。再び接続エラーを受信した場合、同じGPSユニットと対になった別のBluetooth受信機が近くにないことを確認してください。

24.2.4. Examples of GPS devices connection in QGIS

24.2.4.1. GPSMAP 60cs を使用する

MS Windows

最も簡単に動作させる方法は、GPSGate というミドルウェア（フリーウェア、オープンではない）を使うことです。

Launch the program, make it scan for GPS devices (works for both USB and BT ones) and then in QGIS:

  1. In Settings ► Options ► GPS, detect the plugged-in device. You can use the radioButtonOn Autodetect mode.

  2. Press Connect in the GPS Information panel

Ubuntu/Mint GNU/Linux

Windowsにとって簡単な手段は中間にサーバーを使うことであり、この場合はGPSDで、このため、

  1. Install the program

    sudo apt install gpsd

  2. それから garmin_gps カーネルモジュールを読み込みます

    sudo modprobe garmin_gps

  3. And then connect the unit and check with dmesg the actual device being used by the unit, for example /dev/ttyUSB0.

  4. Now you can launch gpsd

    gpsd /dev/ttyUSB0

  5. 最終的にQGIS ライブ追跡ツールで接続します。

24.2.4.2. BTGP-38KM データロガー (Bluetoothのみ)を使用する

GPSD (Linux) またはGPSGate (Windows) を使うと手間が省略できます。

24.2.4.3. BlueMax GPS-4044 データロガー (BT とUSB両方)を使用する

MS Windows

The live tracking works for both USB and BT modes, by using GPSGate or even without it, just use the radioButtonOn Autodetect mode, or point the tool to the right port.

Ubuntu/Mint GNU/Linux

USB

ライブ追跡はGPSDありでも動作しますし

gpsd /dev/ttyACM3

またはそれなしでも、直接デバイス（例えば /dev/ttyACM3 ）にQGISライブ追跡ツールを接続することによって動作します。

Bluetooth

ライブ追跡はGPSDありでも動作しますし

gpsd /dev/rfcomm0

またはそれなしでも、直接デバイス（例えば /dev/rfcomm0 ）にQGISライブ追跡ツールを接続することによって動作します。