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Mercator Projection and Geospatial Circles.html
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Mercator Projection and Geospatial Circles.html
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<!DOCTYPE html>
<html>
<head>
<title>Mercator Projection and Geospatial Circles - Azure Maps Web SDK Samples</title>
<meta charset="utf-8" />
<meta http-equiv="x-ua-compatible" content="IE=Edge" />
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no" />
<meta name="description" content="This sample shows how the Mercator projection of the map affects the scale of geospatially accurate objects on the map." />
<meta name="keywords" content="map, gis, API, SDK, circle, geospatial, mercator, projection" />
<meta name="author" content="Microsoft Azure Maps" />
<!-- Add references to the Azure Maps Map control JavaScript and CSS files. -->
<link rel="stylesheet" href="https://atlas.microsoft.com/sdk/javascript/mapcontrol/2/atlas.min.css" type="text/css" />
<script src="https://atlas.microsoft.com/sdk/javascript/mapcontrol/2/atlas.min.js"></script>
<script type='text/javascript'>
var map, datasource;
function GetMap() {
//Initialize a map instance.
map = new atlas.Map('myMap', {
center: [-45, 70],
view: 'Auto',
//Add your Azure Maps subscription key to the map SDK. Get an Azure Maps key at https://azure.com/maps
authOptions: {
authType: 'subscriptionKey',
subscriptionKey: '<Your Azure Maps Key>'
}
});
//Wait until the map resources are ready.
map.events.add('ready', function () {
//Create a data source and add it to the map.
datasource = new atlas.source.DataSource();
map.sources.add(datasource);
//Create circles and add to the data source.
datasource.add([
//Create a circle that is 750KM in radius over Brazil.
new atlas.data.Feature(new atlas.data.Point([-52, -10]), {
subType: "Circle",
radius: 750000
}),
//Create a second circle that is 750KM in radius, but over Greenland.
new atlas.data.Feature(new atlas.data.Point([-41, 75]), {
subType: "Circle",
radius: 750000
})
]);
//Create a polygon layer to render the filled in area of the circle polygon, and add it to the map.
map.layers.add(new atlas.layer.PolygonLayer(datasource, null, {
fillColor: 'rgba(255, 140, 0, 0.5)'
}));
});
}
</script>
</head>
<body onload="GetMap()">
<div id="myMap" style="position:relative;width:100%;min-width:290px;height:600px;"></div>
<fieldset style="width:calc(100% - 30px);min-width:290px;margin-top:10px;">
<legend>Mercator Projection and Geospatial Circles</legend>
This sample shows how the Mercator projection of the map affects the scale of geospatially accurate objects on the map.
In this sample both circles have a radius of 750KM (750,000 meters). However, the closer the circle is to the North or South pole, the larger and more elliptical it appears.
</fieldset>
</body>
</html>