Book Image

Mastering Geospatial Development with QGIS 3.x - Third Edition

By : Shammunul Islam, Simon Miles, Kurt Menke, GISP, Richard Smith Jr., GISP, Luigi Pirelli, John Van Hoesen, GISP
Book Image

Mastering Geospatial Development with QGIS 3.x - Third Edition

By: Shammunul Islam, Simon Miles, Kurt Menke, GISP, Richard Smith Jr., GISP, Luigi Pirelli, John Van Hoesen, GISP

Overview of this book

QGIS is an open source solution to GIS and widely used by GIS professionals all over the world. It is the leading alternative to 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 and getting you acquainted with the latest QGIS 3.6 updates, this book will take you all the way through to teaching you how to create a spatial database and a GeoPackage. Next, you will learn how to style raster and vector data by choosing and managing different colors. The book will then focus on processing raster and vector data. You will be then taught advanced applications, such as creating and editing vector data. Along with that, you will also learn about the newly updated Processing Toolbox, which will help you develop the advanced data visualizations. The book will then explain to you the graphic modeler, how to create QGIS plugins with PyQGIS, and how to integrate Python analysis scripts with QGIS. By the end of the book, you will understand how to work with all aspects of QGIS and will be ready to use it for any type of GIS work.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
About Packt
Contributors
Preface
Index

Defining coordinate reference systems


QGIS supports hundreds of Coordinate Reference Systems (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 (Custom CRS) tool, which can be found by navigating to Settings and then 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 of how to create a custom CRS. PROJ.4 is another Open Source Geospatial Foundation (OSGeo) (http://osgeo.org) project that's used by QGIS, similar to OGR, Geospatial Data Abstraction Library (GDAL), and Geometry Engine – Open Source (GEOS). This project is for managing coordinate systems and projections...