Table of Contents for
QGIS: Becoming a GIS Power User

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition QGIS: Becoming a GIS Power User by Alexander Bruy Published by Packt Publishing, 2017
  1. Cover
  2. Table of Contents
  3. QGIS: Becoming a GIS Power User
  4. QGIS: Becoming a GIS Power User
  5. QGIS: Becoming a GIS Power User
  6. Credits
  7. Preface
  8. What you need for this learning path
  9. Who this learning path is for
  10. Reader feedback
  11. Customer support
  12. 1. Module 1
  13. 1. Getting Started with QGIS
  14. Running QGIS for the first time
  15. Introducing the QGIS user interface
  16. Finding help and reporting issues
  17. Summary
  18. 2. Viewing Spatial Data
  19. Dealing with coordinate reference systems
  20. Loading raster files
  21. Loading data from databases
  22. Loading data from OGC web services
  23. Styling raster layers
  24. Styling vector layers
  25. Loading background maps
  26. Dealing with project files
  27. Summary
  28. 3. Data Creation and Editing
  29. Working with feature selection tools
  30. Editing vector geometries
  31. Using measuring tools
  32. Editing attributes
  33. Reprojecting and converting vector and raster data
  34. Joining tabular data
  35. Using temporary scratch layers
  36. Checking for topological errors and fixing them
  37. Adding data to spatial databases
  38. Summary
  39. 4. Spatial Analysis
  40. Combining raster and vector data
  41. Vector and raster analysis with Processing
  42. Leveraging the power of spatial databases
  43. Summary
  44. 5. Creating Great Maps
  45. Labeling
  46. Designing print maps
  47. Presenting your maps online
  48. Summary
  49. 6. Extending QGIS with Python
  50. Getting to know the Python Console
  51. Creating custom geoprocessing scripts using Python
  52. Developing your first plugin
  53. Summary
  54. 2. Module 2
  55. 1. Exploring Places – from Concept to Interface
  56. Acquiring data for geospatial applications
  57. Visualizing GIS data
  58. The basemap
  59. Summary
  60. 2. Identifying the Best Places
  61. Raster analysis
  62. Publishing the results as a web application
  63. Summary
  64. 3. Discovering Physical Relationships
  65. Spatial join for a performant operational layer interaction
  66. The CartoDB platform
  67. Leaflet and an external API: CartoDB SQL
  68. Summary
  69. 4. Finding the Best Way to Get There
  70. OpenStreetMap data for topology
  71. Database importing and topological relationships
  72. Creating the travel time isochron polygons
  73. Generating the shortest paths for all students
  74. Web applications – creating safe corridors
  75. Summary
  76. 5. Demonstrating Change
  77. TopoJSON
  78. The D3 data visualization library
  79. Summary
  80. 6. Estimating Unknown Values
  81. Interpolated model values
  82. A dynamic web application – OpenLayers AJAX with Python and SpatiaLite
  83. Summary
  84. 7. Mapping for Enterprises and Communities
  85. The cartographic rendering of geospatial data – MBTiles and UTFGrid
  86. Interacting with Mapbox services
  87. Putting it all together
  88. Going further – local MBTiles hosting with TileStream
  89. Summary
  90. 3. Module 3
  91. 1. Data Input and Output
  92. Finding geospatial data on your computer
  93. Describing data sources
  94. Importing data from text files
  95. Importing KML/KMZ files
  96. Importing DXF/DWG files
  97. Opening a NetCDF file
  98. Saving a vector layer
  99. Saving a raster layer
  100. Reprojecting a layer
  101. Batch format conversion
  102. Batch reprojection
  103. Loading vector layers into SpatiaLite
  104. Loading vector layers into PostGIS
  105. 2. Data Management
  106. Joining layer data
  107. Cleaning up the attribute table
  108. Configuring relations
  109. Joining tables in databases
  110. Creating views in SpatiaLite
  111. Creating views in PostGIS
  112. Creating spatial indexes
  113. Georeferencing rasters
  114. Georeferencing vector layers
  115. Creating raster overviews (pyramids)
  116. Building virtual rasters (catalogs)
  117. 3. Common Data Preprocessing Steps
  118. Converting points to lines to polygons and back – QGIS
  119. Converting points to lines to polygons and back – SpatiaLite
  120. Converting points to lines to polygons and back – PostGIS
  121. Cropping rasters
  122. Clipping vectors
  123. Extracting vectors
  124. Converting rasters to vectors
  125. Converting vectors to rasters
  126. Building DateTime strings
  127. Geotagging photos
  128. 4. Data Exploration
  129. Listing unique values in a column
  130. Exploring numeric value distribution in a column
  131. Exploring spatiotemporal vector data using Time Manager
  132. Creating animations using Time Manager
  133. Designing time-dependent styles
  134. Loading BaseMaps with the QuickMapServices plugin
  135. Loading BaseMaps with the OpenLayers plugin
  136. Viewing geotagged photos
  137. 5. Classic Vector Analysis
  138. Selecting optimum sites
  139. Dasymetric mapping
  140. Calculating regional statistics
  141. Estimating density heatmaps
  142. Estimating values based on samples
  143. 6. Network Analysis
  144. Creating a simple routing network
  145. Calculating the shortest paths using the Road graph plugin
  146. Routing with one-way streets in the Road graph plugin
  147. Calculating the shortest paths with the QGIS network analysis library
  148. Routing point sequences
  149. Automating multiple route computation using batch processing
  150. Matching points to the nearest line
  151. Creating a routing network for pgRouting
  152. Visualizing the pgRouting results in QGIS
  153. Using the pgRoutingLayer plugin for convenience
  154. Getting network data from the OSM
  155. 7. Raster Analysis I
  156. Using the raster calculator
  157. Preparing elevation data
  158. Calculating a slope
  159. Calculating a hillshade layer
  160. Analyzing hydrology
  161. Calculating a topographic index
  162. Automating analysis tasks using the graphical modeler
  163. 8. Raster Analysis II
  164. Calculating NDVI
  165. Handling null values
  166. Setting extents with masks
  167. Sampling a raster layer
  168. Visualizing multispectral layers
  169. Modifying and reclassifying values in raster layers
  170. Performing supervised classification of raster layers
  171. 9. QGIS and the Web
  172. Using web services
  173. Using WFS and WFS-T
  174. Searching CSW
  175. Using WMS and WMS Tiles
  176. Using WCS
  177. Using GDAL
  178. Serving web maps with the QGIS server
  179. Scale-dependent rendering
  180. Hooking up web clients
  181. Managing GeoServer from QGIS
  182. 10. Cartography Tips
  183. Using Rule Based Rendering
  184. Handling transparencies
  185. Understanding the feature and layer blending modes
  186. Saving and loading styles
  187. Configuring data-defined labels
  188. Creating custom SVG graphics
  189. Making pretty graticules in any projection
  190. Making useful graticules in printed maps
  191. Creating a map series using Atlas
  192. 11. Extending QGIS
  193. Defining custom projections
  194. Working near the dateline
  195. Working offline
  196. Using the QspatiaLite plugin
  197. Adding plugins with Python dependencies
  198. Using the Python console
  199. Writing Processing algorithms
  200. Writing QGIS plugins
  201. Using external tools
  202. 12. Up and Coming
  203. Preparing LiDAR data
  204. Opening File Geodatabases with the OpenFileGDB driver
  205. Using Geopackages
  206. The PostGIS Topology Editor plugin
  207. The Topology Checker plugin
  208. GRASS Topology tools
  209. Hunting for bugs
  210. Reporting bugs
  211. Bibliography
  212. Index

Chapter 1. Getting Started with QGIS

In this chapter, we will install and configure the QGIS geographic information system. We will also get to know the user interface and how to customize it. By the end of this chapter, you will have QGIS running on your machine and be ready to start with the tutorials.

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:

Installing QGIS on Windows

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:

Installing QGIS on Windows

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:

Installing QGIS on Windows

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:

Installing QGIS on Windows

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:

Installing QGIS on Windows

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:

Installing QGIS on Windows

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:

Installing QGIS on Windows

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:

Installing QGIS on Windows

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