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

Creating raster surfaces via interpolation


QGIS supports surface interpolation from vector points to a raster using the Interpolation plugin. The Interpolation tool supports Inverse Distance Weighted (IDW) and Triangular Interpolation (TIN). To enable the Interpolation plugin, click on Manage and Install Plugins under Plugins.

As an example of how to use the Interpolation tool, let's use the Pecos DEM Points.shp sample file to interpolate a surface using IDW:

  1. Add Pecos DEM Points.shp to the map canvas.

  2. Open the Interpolation plugin tool by navigating to Raster | Interpolation | Interpolation. The tool is shown in the following figure and uses the Pecos DEM Points.shp sample file as the input vector layer:

    The interface of the Interpolation tool is identical whether IDW or TIN is chosen as the Interpolation method. The only exceptions are the Interpolation method parameters, which can be set by clicking on the configure button (). For this example, we will only cover the IDW parameter (distance...