Book Image

OpenLayers 3: Beginner's Guide

By : Thomas Gratier, Paul Spencer, Erik Hazzard
Book Image

OpenLayers 3: Beginner's Guide

By: Thomas Gratier, Paul Spencer, Erik Hazzard

Overview of this book

<p>This book is a practical, hands-on guide that provides you with all the information you need to get started with mapping using the OpenLayers 3 library.</p> <p>The book starts off by showing you how to create a simple map. Through the course of the book, we will review each component needed to make a map in OpenLayers 3, and you will end up with a full-fledged web map application. You will learn the key role of each OpenLayers 3 component in making a map, and important mapping principles such as projections and layers. You will create your own data files and connect to backend servers for mapping. A key part of this book will also be dedicated to building a mapping application for mobile devices and its specific components.</p>
Table of Contents (22 chapters)
OpenLayers 3 Beginner's Guide
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Transforming coordinates


Transforming a point means you take a coordinate in one projection and turn it into a coordinate of another projection. This operation is also called reprojection. The term reprojection is also applied when deforming a raster image from one projection to another. Apart from transforming EPSG:4326 to EPSG:3857 and vice versa, OpenLayers does not provide support for transforming other projections out-of-the-box. To do transforms with other projections, you can include Proj4js (which can be found at http://proj4js.org) or provide your own transforms and register them with OpenLayers. You may be wondering why. The main reason is to not maintain projections in the core library when we can keep it outside, in a well-maintained library. The other goal, is to avoid increasing the overall library size. There are thousands of projections, whereas most projects only require some of them. The gain is not worth the drawback.

In most scenarios, it is the job of the backend map...