Book Image

Mastering QGIS - Second Edition

By : Kurt Menke, GISP, Paolo Corti, Richard Smith Jr., GISP, Luigi Pirelli, John Van Hoesen, GISP
Book Image

Mastering QGIS - Second Edition

By: Kurt Menke, GISP, Paolo Corti, Richard Smith Jr., GISP, Luigi Pirelli, John Van Hoesen, GISP

Overview of this book

QGIS is an open source solution to GIS. It is widely used by GIS professionals all over the world. It is the leading alternative to the proprietary GIS software. Although QGIS is described as intuitive, it is also by default complex. Knowing which tools to use and how to apply them is essential to producing valuable deliverables on time. Starting with a refresher on the QGIS basics, this book will take you all the way through to creating your first custom QGIS plugin. From the refresher, we will recap how to create, populate, and manage a spatial database. You’ll also walk through styling GIS data, from creating custom symbols and color ramps to using blending modes. In the next section, you will discover how to prepare vector, heat maps, and create live layer effects, labeling, and raster data for processing. You’ll also discover advanced data creation and editing techniques. The last third of the book covers the more technical aspects of QGIS such as using LAStools and GRASS GIS’s integration with the Processing Toolbox, how to automate workflows with batch processing, and how to create graphical models. Finally, you will see how to create and run Python data processing scripts and write your own QGIS plugin with pyqgis. By the end of the book, you will understand how to work with all the aspects of QGIS, and will be ready to use it for any type of GIS work.
Table of Contents (19 chapters)
Mastering QGIS - Second Edition
Credits
Foreword
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Index

Defining coordinate reference systems


QGIS supports hundreds of CRS for data display and analysis. In some cases, however, the supported CRS may not suit your exact needs. QGIS provides the functionality to create custom CRS using the Custom Coordinate Reference System Definition tool that can be found by navigating to Settings | Custom CRS.

In QGIS, a CRS is defined using the PROJ.4 definition format. We must understand the PROJ.4 definition format before we can define a new or modify an existing CRS; therefore, in the first part of this section, we will discuss the basics of PROJ.4, and in the second part, we will walk you through an example to create a custom CRS.

Note

PROJ.4 is another Open Source Geospatial Foundation (http://osgeo.org) project used by QGIS, similar to OGR, GDAL, and GEOS. This project is for managing coordinate systems and projections. For a detailed user manual for the PROJ.4 format used to specify the CRS parameters in QGIS, visit the project website at https://github...