Browse Library
Sign In Start Free Trial
Close icon Search icon
Account
Browse Library Advanced Search Sign In Start Free Trial

Add to playlist

Create a Playlist

Modal Close icon
You need to login to use this feature.
  • Book Overview & Buying QGIS 2 Cookbook
  • Table Of Contents Toc
  • Feedback & Rating feedback
QGIS 2 Cookbook

QGIS 2 Cookbook

By : Mandel, Olaya Ferrero, Anita Graser
5 (1)
Buy this Book
close
close
QGIS 2 Cookbook

QGIS 2 Cookbook

5 (1)
By: Mandel, Olaya Ferrero, Anita Graser
Buy this Book

Overview of this book

QGIS is a user-friendly, cross-platform desktop geographic information system used to make maps and analyze spatial data. QGIS allows users to understand, question, interpret, and visualize spatial data in many ways that reveal relationships, patterns, and trends in the form of maps. This book is a collection of simple to advanced techniques that are needed in everyday geospatial work, and shows how to accomplish them with QGIS. You will begin by understanding the different types of data management techniques, as well as how data exploration works. You will then learn how to perform classic vector and raster analysis with QGIS, apart from creating time-based visualizations. Finally, you will learn how to create interactive and visually appealing maps with custom cartography. By the end of this book, you will have all the necessary knowledge to handle spatial data management, exploration, and visualization tasks in QGIS.
Table of Contents (14 chapters)
close
close
close
Preface
Icon
Preface
Icon
What this book covers
Icon
What you need for this book
Icon
Who this book is for
Icon
Sections
Icon
Conventions
Icon
Reader feedback
Icon
Customer support
Free Chapter
1
1. Data Input and Output
Icon
1. Data Input and Output
Icon
Introduction
Icon
Finding geospatial data on your computer
Icon
Describing data sources
Icon
Importing data from text files
Icon
Importing KML/KMZ files
Icon
Importing DXF/DWG files
Icon
Opening a NetCDF file
Icon
Saving a vector layer
Icon
Saving a raster layer
Icon
Reprojecting a layer
Icon
Batch format conversion
Icon
Batch reprojection
Icon
Loading vector layers into SpatiaLite
Icon
Loading vector layers into PostGIS
2
2. Data Management
Icon
2. Data Management
Icon
Introduction
Icon
Joining layer data
Icon
Cleaning up the attribute table
Icon
Configuring relations
Icon
Joining tables in databases
Icon
Creating views in SpatiaLite
Icon
Creating views in PostGIS
Icon
Creating spatial indexes
Icon
Georeferencing rasters
Icon
Georeferencing vector layers
Icon
Creating raster overviews (pyramids)
Icon
Building virtual rasters (catalogs)
3
3. Common Data Preprocessing Steps
Icon
3. Common Data Preprocessing Steps
Icon
Introduction
Icon
Converting points to lines to polygons and back – QGIS
Icon
Converting points to lines to polygons and back – SpatiaLite
Icon
Converting points to lines to polygons and back – PostGIS
Icon
Cropping rasters
Icon
Clipping vectors
Icon
Extracting vectors
Icon
Converting rasters to vectors
Icon
Converting vectors to rasters
Icon
Building DateTime strings
Icon
Geotagging photos
4
4. Data Exploration
Icon
4. Data Exploration
Icon
Introduction
Icon
Listing unique values in a column
Icon
Exploring numeric value distribution in a column
Icon
Exploring spatiotemporal vector data using Time Manager
Icon
Creating animations using Time Manager
Icon
Designing time-dependent styles
Icon
Loading BaseMaps with the QuickMapServices plugin
Icon
Loading BaseMaps with the OpenLayers plugin
Icon
Viewing geotagged photos
5
5. Classic Vector Analysis
Icon
5. Classic Vector Analysis
Icon
Introduction
Icon
Selecting optimum sites
Icon
Dasymetric mapping
Icon
Calculating regional statistics
Icon
Estimating density heatmaps
Icon
Estimating values based on samples
6
6. Network Analysis
Icon
6. Network Analysis
Icon
Introduction
Icon
Creating a simple routing network
Icon
Calculating the shortest paths using the Road graph plugin
Icon
Routing with one-way streets in the Road graph plugin
Icon
Calculating the shortest paths with the QGIS network analysis library
Icon
Routing point sequences
Icon
Automating multiple route computation using batch processing
Icon
Matching points to the nearest line
Icon
Creating a routing network for pgRouting
Icon
Visualizing the pgRouting results in QGIS
Icon
Using the pgRoutingLayer plugin for convenience
Icon
Getting network data from the OSM
7
7. Raster Analysis I
Icon
7. Raster Analysis I
Icon
Introduction
Icon
Using the raster calculator
Icon
Preparing elevation data
Icon
Calculating a slope
Icon
Calculating a hillshade layer
Icon
Analyzing hydrology
Icon
Calculating a topographic index
Icon
Automating analysis tasks using the graphical modeler
8
8. Raster Analysis II
chevron up
Icon
8. Raster Analysis II
Icon
Introduction
Icon
Calculating NDVI
Icon
Handling null values
Icon
Setting extents with masks
Icon
Sampling a raster layer
Icon
Visualizing multispectral layers
Icon
Modifying and reclassifying values in raster layers
Icon
Performing supervised classification of raster layers
9
9. QGIS and the Web
Icon
9. QGIS and the Web
Icon
Introduction
Icon
Using web services
Icon
Using WFS and WFS-T
Icon
Searching CSW
Icon
Using WMS and WMS Tiles
Icon
Using WCS
Icon
Using GDAL
Icon
Serving web maps with the QGIS server
Icon
Scale-dependent rendering
Icon
Hooking up web clients
Icon
Managing GeoServer from QGIS
10
10. Cartography Tips
Icon
10. Cartography Tips
Icon
Introduction
Icon
Using Rule Based Rendering
Icon
Handling transparencies
Icon
Understanding the feature and layer blending modes
Icon
Saving and loading styles
Icon
Configuring data-defined labels
Icon
Creating custom SVG graphics
Icon
Making pretty graticules in any projection
Icon
Making useful graticules in printed maps
Icon
Creating a map series using Atlas
11
11. Extending QGIS
Icon
11. Extending QGIS
Icon
Introduction
Icon
Defining custom projections
Icon
Working near the dateline
Icon
Working offline
Icon
Using the QspatiaLite plugin
Icon
Adding plugins with Python dependencies
Icon
Using the Python console
Icon
Writing Processing algorithms
Icon
Writing QGIS plugins
Icon
Using external tools
12
12. Up and Coming
Icon
12. Up and Coming
Icon
Introduction
Icon
Preparing LiDAR data
Icon
Opening File Geodatabases with the OpenFileGDB driver
Icon
Using Geopackages
Icon
The PostGIS Topology Editor plugin
Icon
The Topology Checker plugin
Icon
GRASS Topology tools
Icon
Hunting for bugs
Icon
Reporting bugs
13
Index
Icon
Index

Setting extents with masks

The extent of a layer can be set using a second layer, which acts as a mask. This recipe shows you how to do this.

How to do it…

To mask the DEM with the watershed mask, follow these steps:

  1. Open the watershed.tif layer and the dem.tif layer.

  2. Open the Raster Calculator algorithm present in the Processing Toolbox menu.

  3. In Main input layer, select the DEM, and in the Additional layers field, select the watershed layer.

  4. In the Formula field, enter the formula, a*b.

  5. Click on Run to run the algorithm. You will get a masked DEM, as follows:

How it works…

When using the raster calculator, all operations involving a no-data value will result in another no-data value. This means that, when multiplying the DEM layer and the mask layer, in the cells that contain no-data values in the mask layer, the value in the resulting layer will be a no-data value, no matter which elevation value is found in the DEM layer for this cell.

As cells inside the watershed in the mask layer have a value...

Unlock full access

Continue reading for free

A Packt free trial gives you instant online access to our library of over 7000 practical eBooks and videos, constantly updated with the latest in tech
Start a 7-day FREE trial
End of Section 5
Next Section

Create a Note

Modal Close icon
You need to login to use this feature.
notes
bookmark search playlist font-size

Change the font size

margin-width

Change margin width

day-mode

Change background colour

Close icon Search
Country selected
Close icon Your notes and bookmarks

Delete Bookmark

Modal Close icon
Are you sure you want to delete it?
Cancel
Yes, Delete

Delete Note

Modal Close icon
Are you sure you want to delete it?
Cancel
Yes, Delete

Edit Note

Modal Close icon
Write a note (max 255 characters)
Cancel
Update Note

Confirmation

Modal Close icon
claim successful
Order Page Read Now

Buy this book with your credits?

Modal Close icon
Are you sure you want to buy this book with one of your credits?
Close
YES, BUY