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Mastering QGIS

You're reading from   Mastering QGIS Go beyond the basics and unleash the full power of QGIS with practical, step-by-step examples

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Product type Paperback
Published in Mar 2015
Publisher
ISBN-13 9781784398682
Length 420 pages
Edition 1st Edition
Tools
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Toc

Table of Contents (12) Chapters Close

Preface 1. A Refreshing Look at QGIS FREE CHAPTER 2. Creating Spatial Databases 3. Styling Raster and Vector Data 4. Preparing Vector Data for Processing 5. Preparing Raster Data for Processing 6. Advanced Data Creation and Editing 7. The Processing Toolbox 8. Automating Workflows with the Graphical Modeler 9. Creating QGIS Plugins with PyQGIS and Problem Solving 10. PyQGIS Scripting 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...

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