topic Re: How to get the coordinates of each vertex of a polygon? in ArcGIS JavaScript Maps SDK Questions

How to get the coordinates of each vertex of a polygon?

SiyabongaKubeka — Wed, 06 May 2020 10:10:52 GMT

Hi All

I am using a webmap. On it I can drop a point or draw a polygon. I can get the coordinates of the point. Now suppose I am drawing a polygon, how can I get the coordinates of each vertex? Please see my code below:

function (MapView, WebMap, esriConfig, Sketch, GraphicsLayer) {

esriConfig.portalUrl = "https://portal.environment.gov.za/portal";
var webmap = new WebMap({
portalItem: {
id: "04582be14885483da48f29398960f653"
}
});

var graphicsLayer = new GraphicsLayer();

var view = new MapView({
map: webmap,
//zoom: 14,
container: "viewDiv"
});

//var symbol = {
// type: "simple-marker", // autocasts as new SimpleMarkerSymbol()
// style: "circle",
// color: "blue",
// size: "8px", // pixels
// outline: { // autocasts as new SimpleLineSymbol()
// color: [255, 255, 0],
// width: 1 // points
// }
//};

webmap.layers.add(graphicsLayer);

var sketch = new Sketch({
layer: graphicsLayer,
view: view,
//symbol: symbol,
creationMode: "update",
//availableCreateTools: ["point"]
//container: "viewDiv"
});

view.ui.add(sketch, {
position: "top-right"
});

//Listen to sketch widget's create event.

sketch.on('create', function (event) {
// check if the create event's state has changed to complete indicating
// the graphic create operation is completed.
if (event.state === "complete") {

if (view.zoom >= 11) {
let gra = event.graphic.clone();
event.graphic.layer.removeAll();
gra.symbol.color = "red";
gra.layer.add(gra);
console.log(view.zoom);
console.log("X = ", gra.geometry.x);
console.log("Y = ", gra.geometry.y);
console.log("Lat = ", event.graphic.geometry.latitude);
console.log("Long = ", event.graphic.geometry.longitude);
//lati = event.graphic.geometry.latitude;
//longi = event.graphic.geometry.longitude;
zoomLevel = view.zoom;
debugger;
}
else {
alert("please zoom in");
event.graphic.layer.remove(event.graphic);
}
}
});
});
</script>
</head>

Re: How to get the coordinates of each vertex of a polygon?

RobertScheitlin__GISP — Sat, 11 Dec 2021 18:00:50 GMT

You have to loop through the rings of the polygon.

for (var i = 0; i < gra.geometry.rings.length; i++){
  for (var p = 0; p < gra.geometry.rings[i].length; p++){
    var LatLon = String(gra.geometry.rings[i][p]);‍‍‍
    console.log(LatLon);
  }
}‍‍‍‍‍‍

Re: How to get the coordinates of each vertex of a polygon?

SiyabongaKubeka — Thu, 07 May 2020 06:50:22 GMT

Thank you very much Robert, it works.

Re: How to get the coordinates of each vertex of a polygon?

SaiCharanKoppula — Thu, 07 Jul 2022 07:48:59 GMT

I don't get the correct format of longitude and latitude even after using the method provided above

Re: How to get the coordinates of each vertex of a polygon?

GerardoSevilla — Mon, 20 Nov 2023 14:29:58 GMT

Polygon is using spatial Web Mercator coordinate reference system 3857. You will have to transform these coordinates from Web Mercator system to World Geodesic system 4326. I used the following code:

for (var i = 0; i < gra.geometry.rings.length; i++){ for (var p = 0; p < gra.geometry.rings[i].length; p++){ let [x, y] = gra.geometry.rings[i][p]; let lngLat = webMercatorUtils.xyToLngLat(x,y); //get an array with lng,lat vertices.push(lngLat); } }‍‍‍‍‍‍