In this section, we will talk about loading vector data from GIS file formats, such as shapefiles, as well as from text files.

We can load vector files by going to Layer | Add Layer | Add Vector Layer and also using the Add Vector Layer toolbar button. If you like shortcuts, use Ctrl + Shift + V. In the Add vector layer dialog, which is shown in the following screenshot, we find a drop-down list that allows us to specify the encoding of the input file. This option is important if we are dealing with files that contain special characters, such as German umlauts or letters from alphabets different from the default Latin ones.

What we are most interested in now is the Browse button, which opens the file-opening dialog. Note the file type filter drop-down list in the bottom-right corner of the dialog. We can open it to see a list of supported vector file types. This filter is useful to find specific files faster by hiding all the files of a different type, but be...

Whenever we load a data source, QGIS looks for usable CRS information, for example, in the shapefile's .prj file. If QGIS cannot find any usable information, by default, it will ask you to specify the CRS manually. This behavior can be changed by going to Settings | Options | CRS to always use either the project CRS or a default CRS.

The QGIS Coordinate Reference System Selector offers a filter that makes finding a CRS easier. It can filter by name or ID (for example, the EPSG code). Just start typing and watch how the list of potential CRS gets shorter. There are actually two separate lists; the upper one contains the CRS that we recently used, while the lower list is much longer and contains all the available CRS. For the elevp.csv file, we select NAD27 / Alaska Albers. With the correct CRS, the elevp layer will be displayed as shown in this screenshot:

If we want to check a layer's CRS, we can find this information in the layer properties' General...

Loading raster files is not much different from loading vector files. Going to Layer | Add Layer | Add Raster Layer, clicking on the Add Raster Layer button, or pressing the Ctrl + Shift + R shortcut will take you directly to the file-opening dialog. Again, you can check the file type filter to see a list of supported file types.

Let's give it a try and load landcover.img from the raster sample data folder. Similarly to vector files, you can load rasters by dragging them into QGIS from the operating system or the built-in file browser. The following screenshot shows the loaded raster layer:

QGIS supports PostGIS, SpatiaLite, MSSQL, and Oracle Spatial databases. We will cover two open source options: SpatiaLite and PostGIS. Both are available cross-platform, just like QGIS.

SpatiaLite is the spatial extension for SQLite databases. SQLite is a self-contained, server-less, zero-configuration, and transactional SQL database engine (www.sqlite.org). This basically means that a SQLite database, and therefore also a SpatiaLite database, doesn't need a server installation and can be copied and exchanged just like any ordinary file.

You can download an example database from www.gaia-gis.it/spatialite-2.3.1/test-2.3.zip (4 MB). Unzip the file; you will be able to connect to it by going to Layer | Add Layer | Add SpatiaLite Layer, using the Add SpatiaLite Layer toolbar button, or by pressing Ctrl + Shift + L. Click on New to select the test-2.3.sqlite database file. QGIS will save all the connections and add them to the drop-down list at the top. After clicking...

More and more data providers offer access to their datasets via OGC-compliant web services such as Web Map Services (WMS), Web Coverage Services (WCS), or Web Feature Services (WFS). QGIS supports these services out of the box.

You can load WMS layers by going to Layer | Add WMS/WMTS Layer, clicking on the Add WMS/WMTS Layer button, or pressing Ctrl + Shift + W. If you know a WMS server, you can connect to it by clicking on New and filling in a name and the URL. All other fields are optional. Don't worry if you don't know of any WMS servers, because you can simply click on the Add default servers button to get access information about servers whose administrators collaborate with the QGIS project. One of these servers is called Lizardtech server. Select Lizardtech server or any of the other servers from the...