QGIS is a great open-source GIS software package that has come a long way. At the time of this writing, I have only been using QGIS for about 4 months. Before that, I primarily used ArcGIS, and after experiencing both, I can honestly say that QGIS is a more than suitable replacement under most circumstances. This guide will help the GIS user that is unfamiliar with QGIS but has used other software packages, namely ArcGIS. Throughout, I will reference some of the most commonly used functions in ArcGIS and explain their equivalents in QGIS.
First, download the latest version of QGIS by visiting http://www.qgis.org/en/site/forusers/download.html.
After installing QGIS, click Project > New, and the user-interface will look similar to the one below.
In ArcGIS terms, the QGIS Browser Panel is equivalent to the Catalog; there is even a separate application that comes packaged with QGIS called “QGIS Browser”, which has similar a similar functionality to the separate ArcGIS Catalog application.
Use the browser panel to navigate to vector and raster data, and add them to your project by simply dragging and dropping them in the map area (large blank area) or double clicking them. Network locations don’t seem to show up here, so if you need to add one, right click “Favourites”, select “Add a Directory…” and then copy and paste the directory from the address bar of windows explorer.
The layers panel is fairly straight-forward and similar to ArcGIS, except that users are not able to add a new ‘Data Frame’ for multiple combinations of extents/layers. QGIS has the capability to replicate the Data Frame functionality, but that’s for another tutorial (or try searching on Google).
Manage Layers Toolbar (Add Data)
The Manage Layers Toolbar is equivalent to the Add Data button in ArcGIS, except that the user must choose the correct data type button (raster, vector, table, WMS layer, etc.) in QGIS. Users will also notice that QGIS unfortunately does not group multiple files comprising a shapefile (and other file types with multiple files, such as a TIFF with .tif and .prj files) into one neat file. To add a shapefile though, simply select the .shp file, click open twice, and it will be added. Using the browser panel will alleviate this minor nuisance.
Need to “Add XY Data…”?? Use the “Add Delimited Text Layer” button .
This is the same as the ArcToolbox, if not better. For starters, it loads instantly. It has search built-in as opposed to being in a separate window. It also displays all of your saved models (modeling is also quite similar in QGIS compares to the ArcGIS Model Builder…look out for another post on that!). You’ll notice that there are sometimes multiple similar tools appearing in the QGIS, GDAL/OGR, GRASS GIS, and SAGA algorithms. Except for QGIS algorithms, these are all standalone applications that can be downloaded and installed outside of QGIS, but have been conveniently integrated into QGIS. Although the tools are from different software but tend to do the same thing, I would recommend starting off by using a QGIS algorithm if available, and then trying out some of the others as they can be a bit more complicated.
The Select By Location tool does not appear in any toolbar; instead, it is hidden in Vector > Research Tools (or, it can be easily accessed by searching for the name of the tool).
QGIS has a very large and active developer community. If the base QGIS package does not have a tool/function you are looking for, someone has likely created a plugin for it. Click on Plugins > Manage and Install Plugins for a list of plugins that are available. Find the one you need and click Install plugin in the bottom right. Note that only the installed plugins will appear here if you our your company is behind a firewall. If that’s the case, head over to the QGIS Python Plugins Repository. Download the plugin you need by clicking on the name of the plugin, click the Versions tab, click the version number you wish to download, and lastly, click the blue download button in the top right. Extract the zip folder that was downloaded, and then copy/cut the folder inside of the extracted folder (this is important!). Finally, paste the folder in C:\Users\[you]\.qgis2\python\plugins, replacing [you] with your username and C: with the drive you install QGIS on.
Composing a Map
Composing a map is quite different in QGIS compared to ArcGIS. There is no separate layout view and data frame view to switch between. In QGIS, you must click Project > New Print Composer, and name the composer. This will open up the composer, where you will add your map, legend, scalebar, and other elements through the Layout menu button, or clicking the buttons on the far left toolbar. Adding a North Arrow does not have it’s own button; instead, click Add Image, draw the rectangle for the image, click the Item Properties tab in the right middle, expand the Search Directories options, and then scroll through the images to find the north arrow you like. You will also notice that as you change the extent outside of the composer, the extent of the map in the composer does not update. To update the map extent in the composer, make sure that the map element is selected in the composer, and then click the Item Properties tab. Under Extents, click “Set to map canvas extent” (or, feel free to enter your own values in the four extent entry boxes).
Remember that Google is your best friend if you are stuck and having trouble using QGIS. All of my knowledge of QGIS was obtained through Google search results, and there are many places on the web to ask for help. Hopefully I have saved you a bit of time and pointed out some of the most important mapping functionalities that are not so obvious in QGIS. Be sure to check back for more articles that will dive deeper into QGIS!