Google Maps Intersection Detector

HTML

<script src="https://cdn.rawgit.com/bjornharrtell/jsts/gh-pages/1.4.0/jsts.min.js"></script>
<script src="https://maps.google.com/maps/api/js?sensor=false&amp;libraries=drawing"></script>
<div id="map">

</div>

CSS

#map {
  width: 800px;
  height: 400px;
}

JavaScript

var tiledLayer = new google.maps.ImageMapType({
  getTileUrl: function(tileCoord, zoom) {
  	var baseUrl = "https://opencache.statkart.no/gatekeeper/gk/gk.open_wmts?";
    var params = 
      "layer=topo4graatone" +
      "&format=image/png&service=wmts&version=1.0.0" +
      "&request=GetTile&style=default&tilematrixset=EPSG:3857" +
      "&tilematrix=EPSG:3857:" + zoom + "&tilerow=" + tileCoord.y +
      "&tilecol=" + tileCoord.x;
      return baseUrl + params;
  },
  tileSize: new google.maps.Size(256, 256),
  name: "Kartverket",
  maxZoom: 20
});

var mapOptions = {
  zoom: 16,
  center: new google.maps.LatLng(62.1482, 6.0696),  
};

var map = new google.maps.Map(document.getElementById("map"), mapOptions);
map.mapTypes.set('topo4g',tiledLayer);
map.setMapTypeId('topo4g');