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
About the Author
About the Reviewer

Advanced vector styling

This section introduces more advanced vector styling features, building on the basics that we covered in Chapter 2, Viewing Spatial Data. We will cover how to create detailed custom visualizations using the following features:

  • Graduated styles

  • Categorized styles

  • Rule-based styles

  • Data-defined styles

  • Heatmap styles

  • 2.5D styles

  • Layer effects

Creating a graduated style

Graduated styles are great for visualizing distributions of numerical values in choropleth or similar maps. The graduated renderer supports two methods:

  • Color: This method changes the color of the feature according to the configured attribute

  • Size: This method changes the symbol size for the feature according to the configured attribute (this option is only available for point and line layers)

In our sample data, there is a climate.shp file that contains locations and mean temperature values. We can visualize this data using a graduated style by simply selecting the T_F_MEAN value for the Column field and clicking...