In this module we begin using QGIS. We’ll see how to install the software and understand the layout, interface and core functions of the software. By the end of this module, you’ll be on your way to becoming a competent GIS user!
Note that if you have previously installed QGIS, feel free to skip ahead to section three. Otherwise, let’s start here and get QGIS installed.
The QGIS website will look something like this:
QGIS will begin to install. It may take a few minutes to complete.
QGIS will look something like this:
Next we will open up a QGIS project, and take a look at the different pieces of the QGIS interface. If you installed InaSAFE previously, make sure it is closed by clicking on the X in the upper right corner of the InaSAFE panel. If it isn’t open or you haven’t installed it yet, carry on. We will come back to this later.
QGIS should now look something like the following image. Let’s pause for a moment and go over the various components of the QGIS interface.
This is the window where the map is shown. Our project has two different files open, one which shows districts of the Sleman regency, and another that shows the railway line running through the area. Both of these files are drawn together in the map canvas.
On the left side of QGIS is the layers panel. This lists the layers, or files, that are loaded into our QGIS project. In this project, we have two layers, Kecamatan_Sleman and railway_Sleman_OSM.
The layers panel not only shows all the files that are currently open, it also determines the order that they will be drawn on the map canvas. A layer that is at the bottom of the list will be drawn first, and any layers above it will be drawn on top.
Notice how the map canvas changes. The railway layer is now shown below the district layer, and part of the railway is now obscured. A map should never show railway hidden beneath district areas, so go ahead and move the layers back.
At the top of QGIS are a large number of tools, which are contained within various “toolbars”. For example, the File toolbar allows you to save, load, print and start a new project. We already used one of these tools when we opened this project.
By hovering your mouse over an icon, the name of the tool will appear to help you identify each tool. The number of tools (buttons) can seem a bit overwhelming at first, but you will gradually get to know them. The tools are grouped into related functions on toolbars. If you look closely you can see a vertical array of ten dots to the left of each toolbar. By grabbing these with your mouse, you can move the toolbar to a more convenient location, or separate it so that it sits on its own.
If you feel overwhelmed by the number of toolbars, you can customise the interface to see only the tools you use most often, adding or removing toolbars as necessary.
Even if they are not visible in a toolbar, all of your tools will remain accessible via the menus. For example, if you remove the File toolbar (which contains the Save button), you can still save your map by going to Project ‣ Save.
The status bar shows information about the current map. It allows you to adjust the map scale and see the mouse cursor’s coordinates on the map.
The coordinates of this map are the same type of coordinates that are recorded by GPS devices. The status bar shows the longitude and latitude of your mouse cursor.
This may not all be clear right now, but as you progress in your knowledge of GIS, this will make more and more sense.
Now we will add an additional layer containing roads to our project.
One of the most common file formats are shapefiles, which end with the extension .shp. Shapefiles are often used to save geodata, and are commonly used with GIS applications like QGIS.
We’ve already taken a look at the QGIS toolbar and seen the tools for opening a project and adding a new layer. Here’s a list of some other commonly used tools. Feel free to play around with them if you like. The important thing for now is to start getting familiar with QGIS.
|Toggle Editing||Edit features in a layer|
|Pan Map||Drag the map into new location|
|Zoom In||Zoom in on the map|
|Zoom Out||Zoom out on the map|
|Zoom Full||Zoom so that all layers fit in the map window|
|Open Attribute Table||Open a layer’s attribute table|
|Select Single Feature||Select a feature in selected layer|