QGIS, the world's most popular free/open source desktop geographic information system software, enables a wide variety of use cases involving location—formerly only available through expensive, specialized commercial software. However, designing and executing a multitiered project from scratch on this complex ecosystem remains a significant challenge.
This book starts with a primer on QGIS and closely-related data, software, and systems. We'll guide you through seven use-case blueprints for geographic web applications. Each blueprint boils down a complex workflow into steps that you can follow to reduce the time usually lost to trial and error.
By the end of this book, readers will be able to build complex layered applications that visualize multiple datasets, employ different types of visualization, and give end users the ability to interact with and manipulate this data for the purpose of analysis.
Chapter 1, Exploring Places—from Concept to Interface, gives you an overview of the application types and technical aspects that will be covered and how QGIS will be leveraged. through a simple map application example from the digital humanities. You will use some fundamental GIS techniques to produce a tile cache-leveraging web application that includes geocoded addresses, joined data, and a georeferenced image.
Chapter 2, Identifying the Best Places, will look at how raster data can be analyzed, enhanced, and used for map production. You will produce suitability grids using map algebra and export to produce a simple click-based map.
Chapter 3, Discovering Physical Relationships, will create an application for physical raster modeling. We will use raster analysis and a model automation tool to model the physical conditions for some basic hydrological analysis. Finally, you will use a cloud platform to enable dynamic query from the client-side application code.
Chapter 4, Finding the Best Way to Get There, will explore formal, network-like geographic relationships between vector objects. You will learn to create a few visualizations related to optimal paths: isochron polygons and accumulated traffic lines. The end result will be an application that will communicate back and forth with your audience regarding safe school routes.
Chapter 5, Demonstrating Change, will demonstrate visualization and analytical techniques to explore relationships between place and time and between places themselves. You will work with demographic data from a census for election purposes through a timeline controlled animation.
Chapter 6, Estimating Unknown Values, will use interpolation methods to estimate unknown values at one location based on the known values at other locations using the NetCDF array-oriented scientific data format. You will use parameters such as precipitation, relative humidity, and temperature to predict the vulnerability of fields and crops to mildew.
Chapter 7, Mapping for Enterprises and Communities, will use a mix of web services to provide a collaborative data system. You will create an editable and data-rich map for the discovery of community information by accessing information about community assets.
This book is for relatively experienced GIS developers who have a strong grounding in the fundamentals of GIS development. They must have used QGIS before, but are looking to understand how to develop more complex, layered map applications that effectively expose various datasets and visualizations.
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Run QTiles, creating a new mytiles tileset with a minimum zoom of 14 and maximum of 16."
A block of code is set as follows:
[..] > cd c:\packt\c4\data\output c:\packt\c4\data\output>java -jar osm2po-5.0.0\osm2po-core-5.0.0-signed.jar cmd=tj sp newark_osm.osm
Any command-line input or output is written as follows:
cd C:\packt\c6\data\web python -m CGIHTTPServer 8000
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Navigate to Layer | Open attribute table."
Feedback from our readers is always welcome. Let us know what you think about this book—what you liked or disliked. Reader feedback is important for us as it helps us develop titles that you will really get the most out of.
To send us general feedback, simply e-mail <[email protected]>, and mention the book's title in the subject of your message.
If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, see our author guide at www.packtpub.com/authors.
Now that you are the proud owner of a Packt book, we have a number of things to help you to get the most from your purchase.
You can download the example code files from your account at http://www.packtpub.com for all the Packt Publishing books you have purchased. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.
We also provide you with a PDF file that has color images of the screenshots/diagrams used in this book. The color images will help you better understand the changes in the output. You can download this file from: https://www.packtpub.com/sites/default/files/downloads/9071OS_Graphics.pdf.
Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in the text or the code—we would be grateful if you could report this to us. By doing so, you can save other readers from frustration and help us improve subsequent versions of this book. If you find any errata, please report them by visiting http://www.packtpub.com/submit-errata, selecting your book, clicking on the Errata Submission Form link, and entering the details of your errata. Once your errata are verified, your submission will be accepted and the errata will be uploaded to our website or added to any list of existing errata under the Errata section of that title.
To view the previously submitted errata, go to https://www.packtpub.com/books/content/support and enter the name of the book in the search field. The required information will appear under the Errata section.
Piracy of copyrighted material on the Internet is an ongoing problem across all media. At Packt, we take the protection of our copyright and licenses very seriously. If you come across any illegal copies of our works in any form on the Internet, please provide us with the location address or website name immediately so that we can pursue a remedy.
Please contact us at <[email protected]> with a link to the suspected pirated material.
We appreciate your help in protecting our authors and our ability to bring you valuable content.
If you have a problem with any aspect of this book, you can contact us at <[email protected]>, and we will do our best to address the problem.