Book Image

QGIS 2 Cookbook

By : Alex Mandel, Víctor Olaya Ferrero, Anita Graser, Alexander Bruy
Book Image

QGIS 2 Cookbook

By: Alex Mandel, Víctor Olaya Ferrero, Anita Graser, Alexander Bruy

Overview of this book

QGIS is a user-friendly, cross-platform desktop geographic information system used to make maps and analyze spatial data. QGIS allows users to understand, question, interpret, and visualize spatial data in many ways that reveal relationships, patterns, and trends in the form of maps. This book is a collection of simple to advanced techniques that are needed in everyday geospatial work, and shows how to accomplish them with QGIS. You will begin by understanding the different types of data management techniques, as well as how data exploration works. You will then learn how to perform classic vector and raster analysis with QGIS, apart from creating time-based visualizations. Finally, you will learn how to create interactive and visually appealing maps with custom cartography. By the end of this book, you will have all the necessary knowledge to handle spatial data management, exploration, and visualization tasks in QGIS.
Table of Contents (19 chapters)
QGIS 2 Cookbook
About the Authors
About the Reviewers

Converting vectors to rasters

Occasionally, you want to convert vectors to rasters to facilitate using raster analysis tools such as the raster calculator.

Getting ready

You'll need a vector layer; this can be a point, line or polygon layer. The best results generally come from polygon layers. We will use geology_wake2000reclass.shp. This file is the result of the earlier clipping vectors recipe with a new column added that codes the geology types as integers. For reference, you'll also use elev_wake_500m.tif as a matching raster for the area of interest.

How to do it…

In order to be useful in analysis, here's a checklist:

  1. Is the vector data in the same projection as the rest of the raster analysis data? If not, reproject it first. Check the following URL for help,

  2. Clip the vector data to the analysis extent. You may need to convert a raster into a polygon mask to clip it (refer to the clipping vectors...