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## You're reading fromQGIS By Example

Product type Book
Published in Jun 2015
Publisher
ISBN-13 9781782174677
Pages 316 pages
Edition 1st Edition
Languages
Concepts

QGIS By Example
Credits
www.PacktPub.com
Preface
1. Handling Your Data 2. Visualizing and Styling the Data 3. Presenting Data on a Print Map 4. Publishing the Map Online 5. Answering Questions with Density Analysis 6. Answering Questions with Visibility Analysis 7. Answering Questions with Suitability Analysis 8. Automating Analysis with Processing Models 9. Automating Analysis with Processing Scripts 10. Developing a Python Plugin – Select by Radius Index

## Step 2 – combining the DEM and buildings layers

Now, we need to combine the two layers into a single layer by adding their values. Raster algebra is a common approach to overlaying a raster layer (or layers), combining their values using algebraic operations (addition, subtraction, multiplication, division, and so on), and calculating values for a new raster layer. Modern GIS software uses so-called raster calculators that help create, validate, and apply raster algebra expressions to raster datasets.

QGIS also has its own raster calculator located at Raster | Raster Calculator. The Calculator dialog window consists of the following parts:

• Raster bands: In the top-left corner of the window, you can see the list of all rasters available in the project. The raster band number is separated from its name by an `@` sign. If the layer is a single-band raster, then only `name@1` appears in the list, but if it is a multiband raster, then `name@1`, `name@2`, and so on up to `name@n` (where n is the total number...

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