Módulo GPS¶

O que é o GPS?¶

GPS, the Global Positioning System, is a satellite-based system that allows anyone with a GPS receiver to find their exact position anywhere in the world. GPS is used as an aid in navigation, for example in airplanes, in boats and by hikers. The GPS receiver uses the signals from the satellites to calculate its latitude, longitude and (sometimes) elevation. Most receivers also have the capability to store locations (known as waypoints), sequences of locations that make up a planned route and a tracklog or track of the receiver’s movement over time. Waypoints, routes and tracks are the three basic feature types in GPS data. QGIS displays waypoints in point layers, while routes and tracks are displayed in linestring layers.

Carregando dados GPS a partir de um ficheiro¶

There are dozens of different file formats for storing GPS data. The format that QGIS uses is called GPX (GPS eXchange format), which is a standard interchange format that can contain any number of waypoints, routes and tracks in the same file.

To load a GPX file, you first need to load the plugin. Plugins ‣ Plugin Manager... opens the Plugin Manager Dialog. Activate the GPS Tools checkbox. When this plugin is loaded, a button with a small handheld GPS device will show up in the toolbar and in Layer ‣ Create Layer ‣ :

• ^{GPS Tools}
• Create new GPX Layer

For working with GPS data, we provide an example GPX file available in the QGIS sample dataset: qgis_sample_data/gps/national_monuments.gpx. See section Sample Data for more information about the sample data.

1. Select Vector ‣ GPS ‣ GPS Tools or click the ^{GPS Tools} icon in the toolbar and open the Load GPX file tab (see figure_GPS).
2. Browse to the folder qgis_sample_data/gps/, select the GPX file national_monuments.gpx and click [Open].

The GPS Tools dialog window

Use the [Browse...] button to select the GPX file, then use the checkboxes to select the feature types you want to load from that GPX file. Each feature type will be loaded in a separate layer when you click [OK]. The file national_monuments.gpx only includes waypoints.

GPSBabel¶

Since QGIS uses GPX files, you need a way to convert other GPS file formats to GPX. This can be done for many formats using the free program GPSBabel, which is available at http://www.gpsbabel.org. This program can also transfer GPS data between your computer and a GPS device. QGIS uses GPSBabel to do these things, so it is recommended that you install it. However, if you just want to load GPS data from GPX files you will not need it. Version 1.2.3 of GPSBabel is known to work with QGIS, but you should be able to use later versions without any problems.

Importando dados GOS¶

Para importar dados GPS a partir de um ficheiro que não é ficheiro GPX, pode usar a ferramenta Importar outro ficheiro na janela das Ferramentas GPS. Aqui selecciona o ficheiro que que importar (e o tipo de ficheiro), que tipo de elemento quer importar, onde quer armazenar o ficheiro GPX convertido e que nome da nova camada irá ter. Tenha atenção que nem todos os formatos de dados GPS irão suportar os três tipos de elementos, portanto para muitos formatos apenas poderá escolher entre um ou dois tipos.

Transferindo dados GPS a partir do dispositivo¶

QGIS can use GPSBabel to download data from a GPS device directly as new vector layers. For this we use the Download from GPS tab of the GPS Tools dialog (see Figure_GPS_download). Here, we select the type of GPS device, the port that it is connected to (or USB if your GPS supports this), the feature type that you want to download, the GPX file where the data should be stored, and the name of the new layer.

A ferramenta de transferência

O tipo de dispositivo que seleciona no menu do dispositivo GPS determina como o GPSBbabel tentará comunicar com o seu dispositivo GPS. Se nenhum dos tipos disponíveis não trabalha com o seu dispositivo GPS pode criar um novo tipo (veja secção Definindo novos tipos de dispositivos).

A porta pode ser um nome de ficheiro ou outro nome que o seu sistema operativo usa como referência a uma porta física no seu computador no qual o dispositivo GPS está ligado. Pode ser um simples USB, para dispositivos GPS com USB.

• No Linux é algo do género como /dev/ttyS0 ou /dev/ttyS1.

• No Windows é COM1 ou COM2.

When you click [OK], the data will be downloaded from the device and appear as a layer in QGIS.

Uploading os dados GPS para o dispositivo¶

You can also upload data directly from a vector layer in QGIS to a GPS device using the Upload to GPS tab of the GPS Tools dialog. To do this, you simply select the layer that you want to upload (which must be a GPX layer), your GPS device type, and the port (or USB) that it is connected to. Just as with the download tool, you can specify new device types if your device isn’t in the list.

This tool is very useful in combination with the vector-editing capabilities of QGIS. It allows you to load a map, create waypoints and routes, and then upload them and use them on your GPS device.

Definindo novos tipos de dispositivos¶

There are lots of different types of GPS devices. The QGIS developers can’t test all of them, so if you have one that does not work with any of the device types listed in the Download from GPS and Upload to GPS tools, you can define your own device type for it. You do this by using the GPS device editor, which you start by clicking the [Edit devices] button in the download or the upload tab.

To define a new device, you simply click the [New device] button, enter a name, enter download and upload commands for your device, and click the [Update device] button. The name will be listed in the device menus in the upload and download windows – it can be any string. The download command is the command that is used to download data from the device to a GPX file. This will probably be a GPSBabel command, but you can use any other command line program that can create a GPX file. QGIS will replace the keywords %type, %in, and %out when it runs the command.

%type será substituído por -w se está a transferir sítios de interesse, -r se está a transferir rotas e -t se está a transferir trilhos. Estes são as opções da linha de comandos que informam o GPSBabel que tipo de elemento irá transferir.

%in will be replaced by the port name that you choose in the download window and %out will be replaced by the name you choose for the GPX file that the downloaded data should be stored in. So, if you create a device type with the download command gpsbabel %type -i garmin -o gpx %in %out (this is actually the download command for the predefined device type ‘Garmin serial’) and then use it to download waypoints from port /dev/ttyS0 to the file output.gpx, QGIS will replace the keywords and run the command gpsbabel -w -i garmin -o gpx /dev/ttyS0 output.gpx.

O comando de upload é o comando que é usado para fazer upload de dados para o dispositivo. As mesmas palavras-chave são usadas, mas %in é agora substituída pelo o nome do ficheiro GPX para a camada que vai ser feita um upload, e %out é substituída pelo o nome da porta.

You can learn more about GPSBabel and its available command line options at http://www.gpsbabel.org.

Após ter criado um novo tipo de dispositivo irá aparecer na lista de dispositivos para as ferramentas de transferência e upload.

Transferência de pontos/trilhos a partir de unidades GPS¶

As described in previous sections QGIS uses GPSBabel to download points/tracks directly in the project. QGIS comes out of the box with a pre-defined profile to download from Garmin devices. Unfortunately there is a bug #6318 that does not allow create other profiles, so downloading directly in QGIS using the GPS Tools is at the moment limited to Garmin USB units.

ATTRS{idVendor}=="091e", ATTRS{idProduct}=="0003", MODE="666"

rmmod garmin_gps

gpsbabel -t -i skytraq,baud=9600,initbaud=9600 -f COM9 -o gpx -F C:/GPX/aaa.gpx

skytraq: Too many read errors on serial port

gpsbabel -t -i mtk -f COM12 -o gpx -F C:/temp/test.gpx
mtk_logger: Can't create temporary file data.bin
Error running gpsbabel: Process exited unsuccessfully with code 1

gpsbabel -t -i mtk -f /dev/ttyACM3 -o gpx -F /home/user/bluemax.gpx

gpsbabel -t -i mtk -f /dev/rfcomm0 -o gpx -F /home/user/bluemax_bt.gpx