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

Introducing the graphical modeler


A typical spatial analysis involves a series of GIS operations, with the output of one operation as the input for the next one, until the final result is generated. Using the graphical modeler, you can combine these individual steps into a single process. The interface to the graphical modeler allows you to visually draw inputs, GIS algorithms, and outputs. The entire analysis is then ready to run as a custom tool within the Processing Toolbox. The custom tool will look like other tools in the Processing Toolbox. After assigning the inputs and naming the outputs, the entire analysis will run in a single step.

A major benefit of this approach is that the completed analytical workflow can be modified and rerun. This allows stakeholders to understand how changing thresholds or input values affects the results of an analysis. Let's assume that you were assigned the task of developing a site-selection model for a new coffee shop. To match one of the site-selection...