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
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Introduction


This chapter focuses on the common use cases that are related to routing within networks. By far, the most common networks that are used to route are street networks. Other less common cases include networks for indoor routing, that is, through rooms inside buildings, or networks of shipping routes.

Networks and routing are in no way a GIS-only topic. You will find a lot of math literature related to this, called Graph Theory. In this chapter, we will use the following terms to talk about networks:

  • A network (also known as graph) is a collection of connected objects

  • These objects are called nodes (also known as vertices)

  • The connections between nodes are called links (also known as edges)

The following figure explains these terms:

The two routing tools that are commonly used with QGIS are as follows:

  • The Road graph plugin, which is one of the QGIS core plugins; that is, this plugin is available in every QGIS installation, but you may have to activate it in Plugin Manager

  • The PostGIS...