Book Image

Learning QGIS - Third Edition

By : Anita Graser
Book Image

Learning QGIS - Third Edition

By: Anita Graser

Overview of this book

QGIS is a user-friendly open source geographic information system (GIS) that runs on Linux, Unix, Mac OS X, and Windows. The popularity of open source geographic information systems and QGIS in particular has been growing rapidly over the last few years. Learning QGIS Third Edition is a practical, hands-on guide updated for QGIS 2.14 that provides you with clear, step-by-step exercises to help you apply your GIS knowledge to QGIS. Through clear, practical exercises, this book will introduce you to working with QGIS quickly and painlessly. This book takes you from installing and configuring QGIS to handling spatial data to creating great maps. You will learn how to load and visualize existing spatial data and create data from scratch. You will get to know important plugins, perform common geoprocessing and spatial analysis tasks and automate them with Processing. We will cover how to achieve great cartographic output and print maps. Finally, you will learn how to extend QGIS using Python and even create your own plugin.
Table of Contents (13 chapters)
Learning QGIS Third Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Installing QGIS


QGIS runs on Windows, various Linux distributions, Unix, Mac OS X, and Android. The QGIS project provides ready-to-use packages as well as instructions to build from the source code at http://download.qgis.org. We will cover how to install QGIS on two systems, Windows and Ubuntu, as well as how to avoid the most common pitfalls.

Note

Further installation instructions for other supported operating systems are available at http://www.qgis.org/en/site/forusers/alldownloads.html.

Like many other open source projects, QGIS offers you a choice between different releases. For the tutorials in this book, we will use the QGIS 2.14 LTR version. The following options are available:

  • Long-term release (LTR): The LTR version is recommended for corporate and academic use. It is currently released once per year in the end of February. It receives bug fix updates for at least a year, and the features and user interface remain unchanged. This makes it the best choice for training material that should not become outdated after a few months.

  • Latest release (LR): The LR version contains newly developed and tested features. It is currently released every four months (except when an LTR version is released instead). Use this version if you want to stay up to date with the latest developments, including new features and user interface changes, but are not comfortable with using the DEV version.

  • Developer version (DEV, master, or testing): The cutting-edge DEV version contains the latest and greatest developments, but be warned that on some days, it might not work as reliably as you want it to.

Note

You can find more information about the releases as well as the schedule for future releases at http://www.qgis.org/en/site/getinvolved/development/roadmap.html#release-schedule.

For an overview of the changes between releases, check out the visual change logs at http://www.qgis.org/en/site/forusers/visualchangelogs.html.

Installing QGIS on Windows

On Windows, we have two different options to install QGIS, the standalone installer and the OSGeo4W installer:

  • The standalone installer is one big file to download (approximately 280 MB); it contains a QGIS release, the Geographic Resources Analysis Support System (GRASS) GIS, as well as the System for Automated Geoscientific Analyses (SAGA) GIS in one package.

  • The OSGeo4W installer is a small, flexible installation tool that makes it possible to download and install QGIS and many more OSGeo tools with all their dependencies. The main advantage of this installer over the standalone installer is that it makes updating QGIS and its dependencies very easy. You can always have access to both the current release and the developer versions if you choose to, but, of course, you are never forced to update. That is why I recommend that you use OSGeo4W. You can download the 32-bit and 64-bit OSGeo4W installers from http://osgeo4w.osgeo.org (or directly from http://download.osgeo.org/osgeo4w/osgeo4w-setup-x86.exe for the 32-bit version or http://download.osgeo.org/osgeo4w/osgeo4w-setup-x86_64.exe if you have a 64-bit version of Windows). Download the version that matches your operating system and keep it! In the future, whenever you want to change or update your system, just run it again.

Tip

Regardless of the installer you choose, make sure that you avoid special characters such as German umlauts or letters from alphabets other than the default Latin ones (for details, refer to https://en.wikipedia.org/wiki/ISO_basic_Latin_alphabet) in the installation path, as they can cause problems later on, for example, during plugin installation.

When the OSGeo4W installer starts, we get to choose between Express Desktop Install, Express Web-GIS Install, and Advanced Install. To install the QGIS LR version, we can simply select the Express Desktop Install option, and the next dialog will list the available desktop applications, such as QGIS, uDig, and GRASS GIS. We can simply select QGIS, click on Next, and confirm the necessary dependencies by clicking on Next again. Then the download and installation will start automatically. When the installation is complete, there will be desktop shortcuts and start menu entries for OSGeo4W and QGIS.

To install QGIS LTR (or DEV), we need to go through the Advanced Install option, as shown in the following screenshot:

This installation path offers many options, such as Download Without Installing and Install from Local Directory, which can be used to download all the necessary packages on one machine and later install them on machines without Internet access. We just select Install from Internet, as shown in this screenshot:

When selecting the installation Root Directory, as shown in the following screenshot, avoid special characters such as German umlauts or letters from alphabets other than the default Latin ones in the installation path (as mentioned before), as they can cause problems later on, for example, during plugin installation:

Then you can specify the folder (Local Package Directory) where the setup process will store the installation files as well as customize Start menu name. I recommend that you leave the default settings similar to what you can see in this screenshot:

In the Internet connection settings, it is usually not necessary to change the default settings, but if your machine is, for example, hidden behind a proxy, you will be able to specify it here:

Then we can pick the download site. At the time of writing this book, there is only one download server available, anyway, as you can see in the following screenshot:

After the installer fetches the latest package information from OSGeo's servers, we get to pick the packages for installation. QGIS LTR is listed in the desktop category as qgis-ltr (and the DEV version is listed as qgis-dev). To select the LTR version for installation, click on the text that reads Skip, and it will change and display the version number, as shown in this screenshot:

As you can see in the following screenshot, the installer will automatically select all the necessary dependencies (such as GDAL, SAGA, OTB, and GRASS), so we don't have to worry about this:

After you've clicked on Next, the download and installation starts automatically, just as in the Express version.

You have probably noticed other available QGIS packages called qgis-ltr-dev and qgis-rel-dev. These contain the latest changes (to the LTR and LR versions, respectively), which will be released as bug fix versions according to the release schedule. This makes these packages a good option if you run into an issue with a release that has been fixed recently but the bug fix version release is not out yet.

Tip

If you try to run QGIS and get a popup that says, The procedure entry point <some-name> could not be located in the dynamic link library <dll-name>.dll, it means that you are facing a common issue on Windows systems—a DLL conflict. This error is easy to fix; just copy the DLL file mentioned in the error message from C:\OSGeo4W\bin\ to C:\OSGeo4W\apps\qgis\bin\ (adjust the paths if necessary).

Installing on Ubuntu

On Ubuntu, the QGIS project provides packages for the LTR, LR, and DEV versions. At the time of writing this book, the Ubuntu versions Precise, Trusty, Vivid, and Wily are supported, but you can find the latest information at http://www.qgis.org/en/site/forusers/alldownloads.html#debian-ubuntu. Be aware, however, that you can install only one version at a time. The packages are not listed in the default Ubuntu repositories. Therefore, we have to add the appropriate repositories to Ubuntu's source list, which you can find at /etc/apt/sources.list. You can open the file with any text editor. Make sure that you have super user rights, as you will need them to save your edits. One option is to use gedit, which is installed in Ubuntu by default. To edit the sources.list file, use the following command:

sudo gedit /etc/apt/sources.list

Tip

Downloading the example code

You can download the example code files for this book from your account at http://www.packtpub.com. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.

Make sure that you add only one of the following package-source options to avoid conflicts due to incompatible packages. The specific lines that you have to add to the source list depend on your Ubuntu version:

  1. The first option, which is also the default one, is to install the LR version. To install the QGIS LR release on Trusty, add the following lines to your file:

    deb     http://qgis.org/debian trusty main
    deb-src http://qgis.org/debian trusty main
    

    Note

    If necessary, replace trusty with precise, vivid, or wily to fit your system. For an updated list of supported Ubuntu versions, check out http://www.qgis.org/en/site/forusers/alldownloads.html#debian-ubuntu.

  2. The second option is to install QGIS LTR by adding the following lines to your file:

    deb     http://qgis.org/debian-ltr trusty main
    deb-src http://qgis.org/debian-ltr trusty main
    
  3. The third option is to install QGIS DEV by adding these lines to your file:

    deb     http://qgis.org/debian-nightly trusty main
    deb-src http://qgis.org/debian-nightly trusty main
    

    Tip

    The preceding versions depend on other packages such as GDAL and proj4, which are available in the Ubuntu repositories. It is worth mentioning that these packages are often quite old.

  4. The fourth option is to install QGIS LR with updated dependencies, which are provided by the ubuntugis repository. Add these lines to your file:

    deb     http://qgis.org/ubuntugis trusty main
    deb-src http://qgis.org/ubuntugis trusty main
    deb     http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu trusty main
    
  5. The fifth option is QGIS LTR with updated dependencies. Add these lines to your file:

    deb     http://qgis.org/ubuntugis-ltr trusty main
    deb-src http://qgis.org/ubuntugis-ltr trusty main
    deb     http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu trusty main
    
  6. The sixth option is the QGIS master with updated dependencies. Add these lines to your file:

    deb     http://qgis.org/ubuntugis-nightly trusty main
    deb-src http://qgis.org/ubuntugis-nightly trusty main
    deb     http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu trusty main
    

Note

To follow the tutorials in this book, it is recommended that you install QGIS 2.14 LTR with updated dependencies (the fifth option).

After choosing the repository, we will add the qgis.org repository's public key to our apt keyring. This will avoid the warnings that you might otherwise get when installing from a non-default repository. Run the following command in the terminal:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key 3FF5FFCAD71472C4

Note

By the time this book goes to print, the key information might have changed. Refer to http://www.qgis.org/en/site/forusers/alldownloads.html#debian-ubuntu for the latest updates.

Finally, to install QGIS, run the following commands:

sudo apt-get update
sudo apt-get install qgis python-qgis qgis-plugin-grass