Book Image

Practical GIS

Book Image

Practical GIS

Overview of this book

The most commonly used GIS tools automate tasks that were historically done manually—compiling new maps by overlaying one on top of the other or physically cutting maps into pieces representing specific study areas, changing their projection, and getting meaningful results from the various layers by applying mathematical functions and operations. This book is an easy-to-follow guide to use the most matured open source GIS tools for these tasks. We’ll start by setting up the environment for the tools we use in the book. Then you will learn how to work with QGIS in order to generate useful spatial data. You will get to know the basics of queries, data management, and geoprocessing. After that, you will start to practice your knowledge on real-world examples. We will solve various types of geospatial analyses with various methods. We will start with basic GIS problems by imitating the work of an enthusiastic real estate agent, and continue with more advanced, but typical tasks by solving a decision problem. Finally, you will find out how to publish your data (and results) on the web. We will publish our data with QGIS Server and GeoServer, and create a basic web map with the API of the lightweight Leaflet web mapping library.
Table of Contents (22 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Dedication
Preface
14
Appendix

Selecting features in QGIS


There are usually two kinds of selection methods in GIS software. There is one which highlights the selected features, making them visually distinguishable from an other one. Selected features by this soft selection method may or may not be the only candidates for further operations based on our choice. However, there is usually a hard selection called filtering. The difference is that the filtered-out features do not appear either on the canvas or in the attribute table. QGIS makes sure to exclude the filtered-out features from every further operation like they weren't there in the first place. There is one important difference between the style of selection and filtering--we can select features with the mouse; however, we can only filter with SQL expressions.

First, let's select a single feature with the mouse. To select features in QGIS, we have to select the vector layer containing the feature in the Layers Panel. Let's select the administrative boundaries layer...