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

Estimating values based on samples

Interpolation is the idea that, with a set of known values, you can estimate the values of additional points based on their proximity to these known values. This recipe shows you how to use known values at point locations to create a continuous surface (raster) of value estimates. Classic examples include weather data estimations that are based on weather station data (think temperature or rainfall maps), crop yield estimates that are based on sampling parts of a field, and like in this example in this recipe, elevation estimations that are based on the elevation of sampled points.

Getting ready

Activate Interpolation Plugin via Plugin Manager.

Load a point layer with numeric columns, representing the feature of interest. For this recipe, use the poi_names_wake.shp, and the elev_m column, which contains elevation in meters for each point.

How to do it…

  1. Start by loading poi_name_wake.

  2. Zoom to the layer extent.

  3. Open the Interpolation tool by navigating to Raster...