At the end our symbology tab will look like this:Īs an added bonus we can get a quick feature count for the rules.
We add similar rules for woods and grassland. Now you can add further rules by clicking on the ‘plus’ icon at the bottom of the symbology tab. Click ‘OK’ when you are finished with your rule design. We can define a colour and fill style for the buildings. The condition reads that we look for objects whose building key is not empty. But a utility comes to our rescue and the filter expression shown in the image hstore_to_map(other_tags) is not NULL converts the ‘other_tags’ string into a key-value-map where we pick the value for the key ‘building’. QGIS’ expression evaluation cannot directly deal with hstore strings. Treat differently means that rules need to be specified according to layer properties. We’d like to treat buildings differently. We can modify this rule by clicking on the icon marked with a purple square in the image above. The current rendering appears as a rule with no filters. From the context menu of the multipolygon layer select Properties and on that form move to the Symbology tab.įirst change the type of the symbol from “Single symbol” to “Rule based” using the combobox at the top of the form.
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Let us render them differently in order to get a feeling how to identify different objects. Initially they are rendered in the same way which means that islands cover everything else. In this example polygons are mostly islands, forest and buildings. This kind of storage is called “hstore” in a PostgreSQL database and is the standard for OSM data. We can see that all the key-value-pairs for the tags of the various objects are organized in a specially formatted text string in the field ‘other_tags’. You can inspect the data of a vector layer using ‘Open Attribute table’ from the context menu of a layer, in this case the multipolygon layer.
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But as OSM data imported by one of the methods described above have their tags encoded in a special way here is an example how to deal with them (for the curious, the example is pitcairn-islands-latest from Geofabrik’s download page for Australia and Oceania). We cannot give you even a rough overview over what you can do with QGIS and there are many excellent tutorials and books which will guide you step-by-step towards mastering the software. You can choose to re-import the exported layer by checking the box at the bottom (activated by default). The other options on the dialogue vary depending on the format you selected. You can select from a wide range of formats including Shapefile, GeoJSON, PostgreSQL dump, SQLite. To export a layer activate its context menu and select Export -> Save Features as… After clicking “OK” you can close the dialogue and your QGIS window shows the new layers.You can select one or more type layers from that file.In the source field, select your file and click “Add”.Go to Layer -> Add Layer -> Add Vector Layer….Once you used QuickOSM OSM files should have been made known to QGIS and you can use the regular vector layer import: You can either use QuickOSM to import it clicking on ‘OSM File’ in the left bar. There are several options how to obtain ready-made extracts of an area. The data are stored in three temporary layers, one for nodes, ways and polygons respectively. You will be notified when the download is complete.You can select a perimeter (default 1000m) around this node where data will be loaded from the database. Otherwise choose “Around” and a node with this name suffices. Using the default “In” requires that a relation or polygon exists with this name. If you have a layer loaded in QGIS with the correct extent, choose “Layer extent” and select the layer you want to use. You can choose from several options here - if your window already displays the extent you want, switch the combobox which by default shows “In” to “Canvas extent”. Open QGIS and go to Vector -> QuickOSM -> QuickOSM….The QuickOSM plugin allows us to extract large amounts of data as it uses the Overpass api and not the main OSM database server. The first thing we will do is get some up-to-date OSM data. This will add an entry to the Vector menu Obtaining Data from the Database
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To install this plugin open the Manage Plugins dialogue from the Plugins menu. We will use a plugin, QuickOSM, to import data from the OpenStreetMap database.
If you haven’t already done this, you can download it from. We assume that you’ve already downloaded and installed QGIS 3.x. In this chapter we’ll walk through the steps necessary to do this. With QGIS you can access up-to-date OSM data whenever you want, select the tags you want to include, and easily export it into an easy-to-use SQLite database or Shapefile. QGIS (formerly Quantum GIS) is a full-featured, open-source, cross-platform Geographic Information System.
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