EPSG:4326

EPSG:3857

Tissot indicatrix example

Draw Tissot's indicatrices on maps.

Example of Tissot indicatrix maps. The map on the left is an EPSG:4326 map. The one on the right is EPSG:3857.

tissot, circle
<!DOCTYPE html>
<html>
<head>
<title>Tissot indicatrix 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/v3.9.0/css/ol.css" type="text/css">
<script src="http://openlayers.org/en/v3.9.0/build/ol.js"></script>

</head>
<body>
<div class="container-fluid">

<div class="row-fluid">
  <div class="span6">
    <h4>EPSG:4326</h4>
    <div id="map4326" class="map"></div>
  </div>
  <div class="span6">
    <h4>EPSG:3857</h4>
    <div id="map3857" class="map"></div>
  </div>
</div>

</div>
<script>
var vectorLayer4326 = new ol.layer.Vector({
  source: new ol.source.Vector()
});

var vectorLayer3857 = new ol.layer.Vector({
  source: new ol.source.Vector()
});

var map4326 = new ol.Map({
  layers: [
    new ol.layer.Tile({
      source: new ol.source.TileWMS({
        url: 'http://demo.boundlessgeo.com/geoserver/wms',
        params: {
          'LAYERS': 'ne:NE1_HR_LC_SR_W_DR'
        }
      })
    }),
    vectorLayer4326
  ],
  renderer: 'canvas',
  target: 'map4326',
  view: new ol.View({
    projection: 'EPSG:4326',
    center: [0, 0],
    zoom: 2
  })
});

var map3857 = new ol.Map({
  layers: [
    new ol.layer.Tile({
      source: new ol.source.TileWMS({
        url: 'http://demo.boundlessgeo.com/geoserver/wms',
        params: {
          'LAYERS': 'ne:NE1_HR_LC_SR_W_DR'
        }
      })
    }),
    vectorLayer3857
  ],
  renderer: 'canvas',
  target: 'map3857',
  view: new ol.View({
    center: [0, 0],
    zoom: 2
  })
});

var wgs84Sphere = new ol.Sphere(6378137);

var radius = 800000;
var x, y;
for (x = -180; x < 180; x += 30) {
  for (y = -90; y < 90; y += 30) {
    var circle4326 = ol.geom.Polygon.circular(wgs84Sphere, [x, y], radius, 64);
    var circle3857 = circle4326.clone().transform('EPSG:4326', 'EPSG:3857');
    vectorLayer4326.getSource().addFeature(new ol.Feature(circle4326));
    vectorLayer3857.getSource().addFeature(new ol.Feature(circle3857));
  }
}

</script>
</body>
</html>