Table of Contents for
QGIS: Becoming a GIS Power User
QGIS: Becoming a GIS Power User
Published by
Packt Publishing, 2017
- Cover
- Table of Contents
- QGIS: Becoming a GIS Power User
- QGIS: Becoming a GIS Power User
- QGIS: Becoming a GIS Power User
- Credits
- Preface
- What you need for this learning path
- Who this learning path is for
- Reader feedback
- Customer support
- 1. Module 1
- 1. Getting Started with QGIS
- Running QGIS for the first time
- Introducing the QGIS user interface
- Finding help and reporting issues
- Summary
- 2. Viewing Spatial Data
- Dealing with coordinate reference systems
- Loading raster files
- Loading data from databases
- Loading data from OGC web services
- Styling raster layers
- Styling vector layers
- Loading background maps
- Dealing with project files
- Summary
- 3. Data Creation and Editing
- Working with feature selection tools
- Editing vector geometries
- Using measuring tools
- Editing attributes
- Reprojecting and converting vector and raster data
- Joining tabular data
- Using temporary scratch layers
- Checking for topological errors and fixing them
- Adding data to spatial databases
- Summary
- 4. Spatial Analysis
- Combining raster and vector data
- Vector and raster analysis with Processing
- Leveraging the power of spatial databases
- Summary
- 5. Creating Great Maps
- Labeling
- Designing print maps
- Presenting your maps online
- Summary
- 6. Extending QGIS with Python
- Getting to know the Python Console
- Creating custom geoprocessing scripts using Python
- Developing your first plugin
- Summary
- 2. Module 2
- 1. Exploring Places – from Concept to Interface
- Acquiring data for geospatial applications
- Visualizing GIS data
- The basemap
- Summary
- 2. Identifying the Best Places
- Raster analysis
- Publishing the results as a web application
- Summary
- 3. Discovering Physical Relationships
- Spatial join for a performant operational layer interaction
- The CartoDB platform
- Leaflet and an external API: CartoDB SQL
- Summary
- 4. Finding the Best Way to Get There
- OpenStreetMap data for topology
- Database importing and topological relationships
- Creating the travel time isochron polygons
- Generating the shortest paths for all students
- Web applications – creating safe corridors
- Summary
- 5. Demonstrating Change
- TopoJSON
- The D3 data visualization library
- Summary
- 6. Estimating Unknown Values
- Interpolated model values
- A dynamic web application – OpenLayers AJAX with Python and SpatiaLite
- Summary
- 7. Mapping for Enterprises and Communities
- The cartographic rendering of geospatial data – MBTiles and UTFGrid
- Interacting with Mapbox services
- Putting it all together
- Going further – local MBTiles hosting with TileStream
- Summary
- 3. Module 3
- 1. Data Input and Output
- Finding geospatial data on your computer
- Describing data sources
- Importing data from text files
- Importing KML/KMZ files
- Importing DXF/DWG files
- Opening a NetCDF file
- Saving a vector layer
- Saving a raster layer
- Reprojecting a layer
- Batch format conversion
- Batch reprojection
- Loading vector layers into SpatiaLite
- Loading vector layers into PostGIS
- 2. Data Management
- Joining layer data
- Cleaning up the attribute table
- Configuring relations
- Joining tables in databases
- Creating views in SpatiaLite
- Creating views in PostGIS
- Creating spatial indexes
- Georeferencing rasters
- Georeferencing vector layers
- Creating raster overviews (pyramids)
- Building virtual rasters (catalogs)
- 3. Common Data Preprocessing Steps
- Converting points to lines to polygons and back – QGIS
- Converting points to lines to polygons and back – SpatiaLite
- Converting points to lines to polygons and back – PostGIS
- Cropping rasters
- Clipping vectors
- Extracting vectors
- Converting rasters to vectors
- Converting vectors to rasters
- Building DateTime strings
- Geotagging photos
- 4. Data Exploration
- Listing unique values in a column
- Exploring numeric value distribution in a column
- Exploring spatiotemporal vector data using Time Manager
- Creating animations using Time Manager
- Designing time-dependent styles
- Loading BaseMaps with the QuickMapServices plugin
- Loading BaseMaps with the OpenLayers plugin
- Viewing geotagged photos
- 5. Classic Vector Analysis
- Selecting optimum sites
- Dasymetric mapping
- Calculating regional statistics
- Estimating density heatmaps
- Estimating values based on samples
- 6. Network Analysis
- Creating a simple routing network
- Calculating the shortest paths using the Road graph plugin
- Routing with one-way streets in the Road graph plugin
- Calculating the shortest paths with the QGIS network analysis library
- Routing point sequences
- Automating multiple route computation using batch processing
- Matching points to the nearest line
- Creating a routing network for pgRouting
- Visualizing the pgRouting results in QGIS
- Using the pgRoutingLayer plugin for convenience
- Getting network data from the OSM
- 7. Raster Analysis I
- Using the raster calculator
- Preparing elevation data
- Calculating a slope
- Calculating a hillshade layer
- Analyzing hydrology
- Calculating a topographic index
- Automating analysis tasks using the graphical modeler
- 8. Raster Analysis II
- Calculating NDVI
- Handling null values
- Setting extents with masks
- Sampling a raster layer
- Visualizing multispectral layers
- Modifying and reclassifying values in raster layers
- Performing supervised classification of raster layers
- 9. QGIS and the Web
- Using web services
- Using WFS and WFS-T
- Searching CSW
- Using WMS and WMS Tiles
- Using WCS
- Using GDAL
- Serving web maps with the QGIS server
- Scale-dependent rendering
- Hooking up web clients
- Managing GeoServer from QGIS
- 10. Cartography Tips
- Using Rule Based Rendering
- Handling transparencies
- Understanding the feature and layer blending modes
- Saving and loading styles
- Configuring data-defined labels
- Creating custom SVG graphics
- Making pretty graticules in any projection
- Making useful graticules in printed maps
- Creating a map series using Atlas
- 11. Extending QGIS
- Defining custom projections
- Working near the dateline
- Working offline
- Using the QspatiaLite plugin
- Adding plugins with Python dependencies
- Using the Python console
- Writing Processing algorithms
- Writing QGIS plugins
- Using external tools
- 12. Up and Coming
- Preparing LiDAR data
- Opening File Geodatabases with the OpenFileGDB driver
- Using Geopackages
- The PostGIS Topology Editor plugin
- The Topology Checker plugin
- GRASS Topology tools
- Hunting for bugs
- Reporting bugs
- Bibliography
- Index
Once you have found a bug and collected all the potentially useful information about its occurrence, it is time to create a bug report.
This recipe shows you how to file a bug report in a right way.
While QGIS project hosts its own bugtracker, you still need an OSGeo User ID to use it. If you don't have an OSGeo account, create one by filling in the form at https://www.osgeo.org/cgi-bin/ldap_create_user.py.
Go to the QGIS bugtracker at http://hub.qgis.org/projects/quantum-gis/issues and use your OSGeo User ID and password to log in. The Login link is located in the top-right corner of the page.
Before creating a new bug report, it is necessary to make sure this bug has not yet been reported. To do this, perform the following steps:
- Go to the Issues tab.
- In the Filters group, add and configure the necessary filters. For example, the following filters:
- Status: Configure this to find only open issues
- Subject: Configure this to find issues with the given substring in the Subject field
- Click on the Apply link above the issues list to apply your filters:
- Check whether the resulting list contains issues that are similar to one that you found.
All tickets that match your criteria will be listed in the table.
Also, it makes sense to try to find similar issues with the ordinal search functionality:
- Open the Search page at https://hub.qgis.org/search/index/quantum-gis.
- Enter the keywords in the field.
- Select QGIS Application from the combobox.
- If necessary, perform the search only in ticket titles by activating the corresponding checkbox.
- Deactivate all checkboxes under the search field except Issues to find only issues with given keywords.
- Click on the Submit button to start the search.
Results will be displayed as a raw list of all existing tickets (open and closed), which contain keywords in their titles and description:
If your issue is already reported, add your observations to it. If you cannot find anything similar to your problem, it is time to submit a bug report. To do this, perform the following steps:
- Log in to the QGIS bugtracker with your OSGeo user ID and password.
- Go to the QGIS Application project at http://hub.qgis.org/projects/quantum-gis.
- Open the New issue tab by clicking on the corresponding link in the menu and populate the form with the requested information:
This form contains many fields, the most important ones are listed as follows:
- Tracker: This defines the ticket type. For bug reports, select Bug Report.
- Subject: This is a short and clear description of the problem. It will be used as the ticket title.
- Description: This is a full description of the issue. Describe your problem in detail and provide steps to reproduce it. If there are any debug messages in the console, backtraces, or minidumps, include or attach them, as well as the sample dataset. If you suspect that bug is related to the specific platform version or a specific version of the third-party dependency package (for example, GDAL, GEOS, SpatiaLite, and so on) provide this information too.
- Priority: This is where you set the anticipated importance of the bug. Currently, the following classification is used:
- Low: This is used for bugs that does not affect day-to-day usage of QGIS
- Normal: This is the default value for all new bug reports and feature requests
- High: This is used for bugs that have a significant impact on QGIS usability in some cases, but at the same time, they do not block QGIS usage in other tasks
- Blocker: This is used for bugs that make QGIS totally unusable, leads to data loss or corruption, or for regressions from previous QGIS versions
- Component: This chooses the most appropriate subsystem of QGIS, which is closely related to the issue.
- Platform and Platform version: This specifies the operating system and its version, respectively.
- Causes crash or corruption: This activates the checkbox if the bug causes a QGIS crash or data loss or corruption.
Check the formatting of the bug report by clicking on the Preview link at the bottom. To submit a bug report, click on the Submit button.
Bug Tracker is a database with information about bugs. Developers look over bug queue and arrange them according to priorities, available resources, and fix them. Fixes usually go to the development version (the so-called "master"), but fixes for regressions and important bugs also go to the long-term release branch.
Using the QGIS Bug Tracker, you also can leave feature requests and submit patches. However, for the latter, creating a pull-request at GitHub is preferable.
- More information about OSGeo User ID can be found at http://www.osgeo.org/osgeo_userid.
- Additional information about using QGIS Bug Tracker can be found at the following wiki page https://hub.qgis.org/wiki/17/Bugreports.
- Also, the BUGS document in the QGIS source tree contains some useful tips. You can find it in the QGIS GitHub repository at https://github.com/qgis/QGIS/blob/master/BUGS.