Book Image

Mastering QGIS

Book Image

Mastering QGIS

Overview of this book

Table of Contents (18 chapters)
Mastering QGIS
Credits
Foreword
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Converting vector geometries


Sometimes, it is necessary to make conversions among point, line, and polygon vector geometries. For example, you may need to generate point centroids from zip code polygons or a town boundary polygon from a line layer. Such conversions may be necessary to put the data into the most appropriate geometry for analysis. For example, if you need to determine the acreage of parcels, but they are provided in a line format, you will need to convert them to polygons to calculate their areas. Sometimes, you may want to convert geometries for cartographic reasons, such as converting polygons to points to create label points. The following tools can be found on the Geometry Tools menu under Vector:

Creating polygon centroids

With the Polygon Centroids tool that can be found by navigating to Vector | Geometry Tools, you can generate points that will be located at the center of polygons. Simply provide the input polygon layer and name the output. In the following example, centroids...