www.it-ebooks.info Python Geospatial Development Build a complete and sophisticated mapping application from scratch using Python tools for GIS development Erik Westra BIRMINGHAM - MUMBAI www.it-ebooks.info Python Geospatial Development Copyright © 2010 Packt Publishing All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews. Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book. Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information. First published: December 2010 Production Reference: 1071210 Published by Packt Publishing Ltd. 32 Lincoln Road Olton Birmingham, B27 6PA, UK. ISBN 978-1-849511-54-4 www.packtpub.com Cover Image by Asher Wishkerman (a.wishkerman@mpic.de) www.it-ebooks.info Credits Author Erik Westra Reviewers Tomi Juhola Silas Toms Acquisition Editor Steven Wilding Development Editor Hyacintha D'Souza Technical Editor Kartikey Pandey Indexers Hemangini Bari Tejal Daruwale Editorial Team Leader Mithun Sehgal Project Team Leader Priya Mukherji Project Coordinator Jovita Pinto Proofreader Jonathan Todd Graphics Nilesh R. Mohite Production Coordinator Kruthika Bangera Cover Work Kruthika Bangera www.it-ebooks.info About the Author Erik Westra has been a professional software developer for over 25 years, and has worked almost exclusively in Python for the past decade. Erik's early interest in graphical user-interface design led to the development of one of the most advanced urgent courier dispatch systems used by messenger and courier companies worldwide. In recent years, Erik has been involved in the design and implementation of systems matching seekers and providers of goods and services across a range of geographical areas. This work has included the creation of real-time geocoders and map-based views of constantly changing data. Erik is based in New Zealand, and works for companies worldwide. "For Ruth, The love of my life." www.it-ebooks.info About the Reviewers Tomi Juhola is a software development professional from Finland. He has a wide range of development experience from embedded systems to modern distributed enterprise systems in various roles, such as tester, developer, consultant, and trainer. Currently, he works in a company called Lindorff and shares this time between development lead duties and helping other projects to adopt Scrum and agile methodologies. He likes to spend his free time with new and interesting development languages and frameworks. Silas Toms is a GIS Analyst for ICF International, working at the San Francisco and San Jose ofces. His undergraduate degree is in Geography (from Humboldt State University), and he is currently nishing a thesis for an MS in GIS at San Francisco State University. He has been a GIS professional for four years, working with many local and regional governments before taking his current position. Python experience was gained through classes at SFSU and professional experience. This is the rst book he has helped review. I would like to thank everyone at Packt Publishing for allowing me to help review this book and putting up with my ever-shifting schedule. I would also like to thank my family for being supportive in my quest to master this somewhat esoteric eld, and for never asking if I am going to teach with this degree. www.it-ebooks.info www.PacktPub.com Support les, eBooks, discount offers and more You might want to visit www.PacktPub.com for support les and downloads related to your book. Did you know that Packt offers eBook versions of every book published, with PDF and ePub les available? You can upgrade to the eBook version at www.PacktPub. com and as a print book customer, you are entitled to a discount on the eBook copy. Get in touch with us at service@packtpub.com for more details. 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Simply use your login credentials for immediate access. www.it-ebooks.info www.it-ebooks.info Table of Contents Preface 1 Chapter 1: Geo-Spatial Development Using Python 7 Python 7 Geo-spatial development 9 Applications of geo-spatial development 11 Analyzing geo-spatial data 12 Visualizing geo-spatial data 13 Creating a geo-spatial mash-up 16 Recent developments 17 Summary 19 Chapter 2: GIS 21 Core GIS concepts 21 Location 22 Distance 25 Units 27 Projections 28 Cylindrical projections 29 Conic projections 31 Azimuthal projections 31 The nature of map projections 32 Coordinate systems 32 Datums 35 Shapes 36 GIS data formats 37 Working with GIS data manually 39 Summary 46 www.it-ebooks.info [...]... introduction to the Python Standard Library and the Python Package Index • What the terms "geo-spatial data" and "geo-spatial development" refer to • An overview of the process of accessing, manipulating, and displaying geo-spatial data • Some of the major applications for geo-spatial development • Some of the recent trends in the field of geo-spatial development Python Python (http:/ /python. org) is a... address it [6] www.it-ebooks.info Geo-Spatial Development Using Python This chapter provides an overview of the Python programming language and geo-spatial development Please note that this is not a tutorial on how to use the Python language; Python is easy to learn, but the details are beyond the scope of this book In this chapter, we will cover: • What the Python programming language is, and how it... display geo-spatial data efficiently using a range of Python tools for GIS development www.it-ebooks.info Preface What this book covers Chapter 1, Geo-Spatial Development Using Python, introduces the Python programming language and the main concepts behind geo-spatial development Chapter 2, GIS, discusses many of the core concepts that underlie GIS development It examines the common GIS data formats,... In this chapter, we briefly introduced the Python programming language and the main concepts behind geo-spatial development We have seen: • That Python is a very high-level language eminently suited to the task of geospatial development • That there are a number of libraries that can be downloaded to make it easier to perform geo-spatial development work in Python • That the term "geo-spatial data"... the past several years on a completely new, non-backwards-compatible version called Python 3 Eventually, Python 3 will replace Python 2.x, but at this stage most of the third-party libraries (including all the GIS tools we will be using) only work with Python 2.x For this reason, we won't be using Python 3 in this book Python is in many ways an ideal programming language Once you are familiar with the... important concepts within geo-spatial application development Chapter 8, Using Python and Mapnik to Generate Maps, helps us to explore the Mapnik map-generation toolkit in depth Chapter 9, Web Frameworks for Python Geo-Spatial Development, discusses the geo-spatial web development landscape, examining the major concepts behind geo-spatial web application development, some of the main open protocols used... install And, if that isn't enough, many other systems provide python bindings to allow you to access them directly from within your programs We will be making heavy use of Python bindings in this book It should be pointed out that there are different versions of Python available Python 2.x is the most common version in use today, while the Python developers have been working for the past several years... nowadays Python has been used for writing web-based systems, desktop applications, games, scientific programming, and even utilities and other higher-level parts of various operating systems www.it-ebooks.info Geo-Spatial Development Using Python Python supports a wide range of programming idioms, from straightforward procedural programming to object-oriented programming and functional programming While Python. .. directly in Python code Programming in Python is straightforward, efficient and, dare I say it, fun Geo-spatial development The term Geo-spatial refers to information that is located on the Earth's surface using coordinates This can include, for example, the position of a cell phone tower, the shape of a road, or the outline of a country: [9] www.it-ebooks.info Geo-Spatial Development Using Python Geo-spatial... working with databases—the list goes on What you can do with the Python Standard Libraries is truly amazing [8] www.it-ebooks.info Chapter 1 As well as the built-in modules in the Python Standard Libraries, it is easy to download and install custom modules, which can be written in either Python or C The Python Package Index (http://pypi .python. org) provides thousands of additional modules that you can . www.it-ebooks.info Python Geospatial Development Build a complete and sophisticated mapping application from scratch using Python tools for GIS development Erik Westra BIRMINGHAM - MUMBAI www.it-ebooks.info Python. access. www.it-ebooks.info www.it-ebooks.info Table of Contents Preface 1 Chapter 1: Geo-Spatial Development Using Python 7 Python 7 Geo-spatial development 9 Applications of geo-spatial development 11 Analyzing geo-spatial data 12 Visualizing. efciently using a range of Python tools for GIS development. www.it-ebooks.info Preface [ 2 ] What this book covers Chapter 1, Geo-Spatial Development Using Python, introduces the Python programming