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

Raster resampling


Raster resampling prepares the raster for display when not every raster cell can be mapped to its own pixel on the display. If each raster cell is mapped to its own display pixel, the raster renders at full resolution (also known as 1:1). However, since screen sizes are limited and we may wish to enlarge or reduce the size of the raster as we work at different map scales, the raster cells must be mapped to more than one pixel or a number of raster cells must be combined, or dropped, to map to a single pixel. As some raster cells cannot be shown at different resolutions, QGIS must determine how to render the raster and still maintain the character of the full-resolution raster. This section will discuss the parameters available for determining how the raster will be resampled for display.

The Resampling section of the raster Style tab has three parameters: Zoomed: in, Zoomed: out, and Oversampling. The Resampling section with its default parameters is shown in the following...