Example of using <code>ol.source.Cluster</code>.
This example shows how to do clustering on point features.
<!DOCTYPE html> <html> <head> <title>Clustering example</title> <script src="https://code.jquery.com/jquery-1.11.2.min.js"></script> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css"> <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script> <link rel="stylesheet" href="http://openlayers.org/en/3.8.1/css/ol.css" type="text/css"> <script src="http://openlayers.org/en/3.8.1/build/ol.js"></script> </head> <body> <div class="container-fluid"> <div class="row-fluid"> <div class="span12"> <div id="map" class="map"></div> </div> </div> </div> <script> var count = 20000; var features = new Array(count); var e = 4500000; for (var i = 0; i < count; ++i) { var coordinates = [2 * e * Math.random() - e, 2 * e * Math.random() - e]; features[i] = new ol.Feature(new ol.geom.Point(coordinates)); } var source = new ol.source.Vector({ features: features }); var clusterSource = new ol.source.Cluster({ distance: 40, source: source }); var styleCache = {}; var clusters = new ol.layer.Vector({ source: clusterSource, style: function(feature, resolution) { var size = feature.get('features').length; var style = styleCache[size]; if (!style) { style = [new ol.style.Style({ image: new ol.style.Circle({ radius: 10, stroke: new ol.style.Stroke({ color: '#fff' }), fill: new ol.style.Fill({ color: '#3399CC' }) }), text: new ol.style.Text({ text: size.toString(), fill: new ol.style.Fill({ color: '#fff' }) }) })]; styleCache[size] = style; } return style; } }); var raster = new ol.layer.Tile({ source: new ol.source.MapQuest({layer: 'sat'}) }); var raw = new ol.layer.Vector({ source: source }); var map = new ol.Map({ layers: [raster, clusters], renderer: 'canvas', target: 'map', view: new ol.View({ center: [0, 0], zoom: 2 }) }); </script> </body> </html>