Book Image

QGIS 2 Cookbook

By : Alex Mandel, Víctor Olaya Ferrero, Anita Graser, Alexander Bruy
Book Image

QGIS 2 Cookbook

By: Alex Mandel, Víctor Olaya Ferrero, Anita Graser, Alexander Bruy

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 (19 chapters)
QGIS 2 Cookbook
About the Authors
About the Reviewers

Creating spatial indexes

Spatial indexes are methods to speed up queries of geometries. This includes speeding up the display of database layers in QGIS when you zoom in close (it has no effect on viewing entire layers).

This recipe applies to SpatiaLite and PostGIS databases. In the event that you've made a new table or you have imported some data and didn't create a spatial index, it's usually a good idea to add this.


You can also create a spatial index for shapefile layers. Take a look at Layer Properties | General for the Create Spatial Index button. This will create a .qix file that works with QGIS, Mapserver, GDAL/OGR, and other open source applications. Refer to

Getting ready

You'll need a SpatiaLite and a Postgis database. For ease, import a vector layer from the provided sample data and do not select the Create spatial index option when importing. (Not sure how to import data? Refer to Chapter 1, Data Input and Output, for how to do this....