Book Image

QGIS 2 Cookbook

By : Mandel, Olaya Ferrero, Anita Graser
Book Image

QGIS 2 Cookbook

By: Mandel, Olaya Ferrero, Anita Graser

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 (14 chapters)
13
Index

Working near the dateline

If you read the previous recipe about custom projections, you might have noticed the note about data that crosses the edge of projections and how it doesn't usually render properly. When working on data near -180 or 180 degrees longitude, you are going to have this issue. Maps showing far Eastern Russia, Fiji, New Zealand, and the South Pacific, to name a few places, will often contend with this issue.

The required solution really depends on what you're trying to do. If you just need a map of such areas, pick a locally suitable projection. If you have existing data from other sources, it may be cut along the edge and you might need to stitch it back together. As for worldwide maps, sometimes you have to trim .01 degrees of the edge of your data so that it doesn't display oddly.

Getting ready

To follow this recipe, you will need the honolulu-flights.shp layer and the SpatiaLite database new-zealand.sqlite from the sample data.

How to do it…

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