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

Rescaling raster values


When an analysis calls for multiple rasters to be combined mathematically, it is often desirable to have the values in each raster converted to a common scale. For example, in a site-selection analysis, you need the data values for the input rasters to be scaled from 0 to 100. This can be done by navigating to Processing Toolbox | GRASS commands | Raster | r.rescale tool. In the following example, the RiparianSurface.img raster with values ranging from 10 to 95.5 will be rescaled to a raster with values ranging from 0 to 100. To do this, perform the following steps:

  1. Select the input raster layer by clicking on the down arrow to choose a raster loaded in the canvas, or by clicking on the browse button.

  2. Specify The input data range to be rescaled.

  3. Specify The output data range.

  4. Select the output raster layer by clicking on the browse button and choosing Save to a temporary file or Save to file: