You're reading from Building Mapping Applications with QGIS Create your own sophisticated applications to analyze and display geospatial information using QGIS and Python

Product type Paperback

Published in Dec 2014

Publisher Packt

ISBN-13 9781783984664

Length 264 pages

Edition 1st Edition

Tools

QGIS

Concepts

Geospatial Analysis

Author (1):

Westra

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Table of Contents (11) Chapters

Preface

1. Getting Started with QGIS FREE CHAPTER

2. The QGIS Python Console

3. Learning the QGIS Python API

4. Creating QGIS Plugins

5. Using QGIS in an External Application

6. Mastering the QGIS Python API

7. Selecting and Editing Features in a PyQGIS Application

8. Building a Complete Mapping Application using Python and QGIS

9. Completing the ForestTrails Application

Index

Using the PyQGIS library

In the previous section, we looked at a number of classes provided by the PyQGIS library. Let's make use of these classes to perform some real-world geospatial development tasks.

Analyzing raster data

We're going to start by writing a program to load in some raster-format data and analyze its contents. To make this more interesting, we'll use a Digital Elevation Model (DEM) file, which is a raster format data file that contains elevation data.

The Global Land One-Kilometer Base Elevation Project (GLOBE) provides free DEM data for the world, where each pixel represents one square kilometer of the Earth's surface. GLOBE data can be downloaded from http://www.ngdc.noaa.gov/mgg/topo/gltiles.html. Download the E tile, which includes the western half of the USA. The resulting file, which is named e10g, contains the height information you need. You'll also need to download the e10g.hdr header file so that QGIS can read the file—you can download...