Introduction

This chapter talks about vector layers. In addition to raster imagery, vector information is the other important type of data that we can work with in a GIS system. Throughout the coming recipes, we'll summarize the most common and important concepts that you may need to work with in OpenLayers.

Note

We will make some AJAX requests during this chapter. If you're following along with this book's source code, then be sure to download and install Node.js (https://nodejs.org) and follow the README.md instructions.

In GIS, a real-world phenomenon is represented by the concept of a feature. This can be a place, such as a city or a village; it can be a road or a railway, it can be a region, a lake, the border of a country, or something entirely arbitrary.

Features can have a set of attributes, such as population, length, and so on. These can be represented visually through the use of points, lines, polygons, and so on, using some visual style: color, radius, width, and so on.

As you can...