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

Converting points to lines to polygons and back – QGIS


Sometimes your data is vector formatted (point, line, or polygon), but it is not the right kind of vector for a particular type of analysis. Or perhaps you need to split a vector in a particular way to facilitate some analysis or cartography. Thankfully, all vector formats are related, lines are two or more connected points, polygons are lines whose first and last point are the same, multipolygons are two or more polygons for the same record, and rings are nested polygons where the inner polygon outlines an area to be excluded. This recipe covers how to convert between the different vector types using built-in QGIS methods.

Getting ready

To convert points to lines or polygons, you will need a shapefile with an ID column that has a single value shared between the points of the same line or polygon. In the following example, we will use census_wake_2000_points.shp.

You will also need to install and activate the Points2One plugin. Refer to...