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

Styling multiband rasters


The multiband color band renderer stretches three gradients (red, green, and blue) to three separate raster bands. The basic idea is that the computer will display natively used combinations of red, green, and blue lights to create the desired image. By matching individual raster bands to the red, green, and blue lights used by the display, the three bands' colors will mix so that they are perceived as other colors, thereby creating a red, green, and blue image composite that is suitable for display.

Contrast enhancements are available to adjust the way the gradients are stretched across the raster bands' values. Contrast enhancements have already been covered in the Singleband gray raster band rendering section, so refer to this section for an in-depth coverage of the topic.

Let's see how multiband rasters are rendered in QGIS. Add TL_ASTER.jpg from the sample data to the QGIS canvas. This sample image is a TerraLook image derived from an ASTER image. Open the Style...