Book Image

Python Geospatial Development - Third Edition

By : Erik Westra
Book Image

Python Geospatial Development - Third Edition

By: Erik Westra

Overview of this book

Geospatial development links your data to locations on the surface of the Earth. Writing geospatial programs involves tasks such as grouping data by location, storing and analyzing large amounts of spatial information, performing complex geospatial calculations, and drawing colorful interactive maps. In order to do this well, you’ll need appropriate tools and techniques, as well as a thorough understanding of geospatial concepts such as map projections, datums, and coordinate systems. This book provides an overview of the major geospatial concepts, data sources, and toolkits. It starts by showing you how to store and access spatial data using Python, how to perform a range of spatial calculations, and how to store spatial data in a database. Further on, the book teaches you how to build your own slippy map interface within a web application, and finishes with the detailed construction of a geospatial data editor using the GeoDjango framework. By the end of this book, you will be able to confidently use Python to write your own geospatial applications ranging from quick, one-off utilities to sophisticated web-based applications using maps and other geospatial data.
Table of Contents (20 chapters)
Python Geospatial Development Third Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Sources of geospatial data in vector format


Vector-based geospatial data represents physical features as collections of points, lines, and polygons. Often, these features will have metadata associated with them. In this section, we will look at some of the major sources of free vector-format geospatial data.

OpenStreetMap

OpenStreetMap (http://openstreetmap.org) is a site where people can collaborate to create and edit geospatial data. It is described as a "free, editable map of the whole world that is being built by volunteers largely from scratch and released with an open-content license."

The following screen snapshot shows a portion of a street map for Onchan, Isle of Man, based on data from OpenStreetMap:

The OpenStreetMap data format

OpenStreetMap does not use a standard format such as shapefiles to store its data. Instead, it has developed its own XML-based format for representing geospatial data in the form of nodes (single points), ways (sequences of points that define a line), areas...