Create, display, and evaluate geodata with QGIS

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If you want to add data from a WMS server to your own project, you need to know its URL. You can usually find the URL on the providers' website and copy it to the clipboard first. Then open the Add Layer | Layer | WMS dialog in QGIS. In the new window, enter the URL in the input field and give the map a meaningful name. A final click on OK accepts the data (Figure 4).

Figure 4: Adding data from a WMS server.

You can usually adjust the size of the data provided on the WMS server to your needs by setting an appropriate value in the Magnification box below the map area. However, the program reloads the maps from the server each time. Complex projects therefore require a fast Internet connection. The integration of large, high-resolution maps into a project also puts a great strain on the computer, as it has to render very large amounts of data. Depending on the hardware, it can take more than ten seconds for a new map to appear.

Geodata that you obtain from a WMS server and integrate into your project cannot be modified. You insert the WMS data like locally stored raster and vector data as layers into your project (Figure 5).

Figure 5: The WMS data is easily integrated and appears as layers for the project.

Tile Server Fix

QGIS also allows you to integrate external data from OpenStreetMap and other services. However, the change from version 2.18 "Las Palmas" to the new version 3.0 "Girona" resulted in some problems.

With the older QGIS versions, a plugin named QuickMapServices could be integrated into the program via the dialog Extensions | Manage and Install Extensions…, which then offered convenient access to the relevant services via the Web menu. By the way, the same applies to several other addons, which are not yet available for the new version. However, the developers are gradually completing the plugin list.

Until then, you need to integrate this external data into your installation via tile servers. The tile servers provide tiles with raster data [3]. First you copy the desired URL to the clipboard. Then open the XYZ Tiles dialog in the QGIS browser segment by right-clicking on it and then clicking on the New Connection…. option. In the dialog that now opens, copy the URL into the corresponding input field. To allow the program to call the URL correctly, remove all $ symbols from it.

Do-It-Yourself

To insert your own data into maps, generate files in shapefile format (a geospacial vector data format for GIS software) [4]. Then fill the files with the desired raw data. For example, you might wish to add the coordinates of roads, railway lines, waterways, or buildings. The software saves these files as individual layers that can be shown or hidden.

To create a shapefile, select the Create Shapefile Layer…. option in the Layer | Create Layer menu. First enter the data type and the coordinate system in the dialog. When entering the coordinate system, make sure that it corresponds to the base plane. Then enter the fields, where you can choose between different types. Note that QGIS does not support non-standard characters.

Then click the Add to Field List button to add the new field to the list at the bottom of the window. OK closes the window and opens the file manager for saving the shapefile in the older program versions. When the file is saved, the software transfers the file with the arbitrary assigned name to the layer segment.

Then fill the shapefile with the desired data. Select the layer and then activate the editing mode by clicking on the Switch editing mode button in the upper-left corner of the program window. Then click on the Add object button and select a corresponding object in the map view on the right side of the program window.

A mouse click on the desired object opens an attribute window in which you enter the different properties of the object based on the predefined shape files. Complete the entry by pressing OK. The software then transfers the new object to the map view.

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