topic Re: Getting Polygon points as Lat and Lon in ArcGIS JavaScript Maps SDK Questions

Getting Polygon points as Lat and Lon

Aeseir — Thu, 02 Jun 2022 10:54:00 GMT

I am trying to get polygon points as Lat and Long coordinates, but cannot find doco that explains how.

this is how far i got to:

var polygonGeo = graphicGeometry as Polygon; console.log(polygonGeo.rings.toString()); for (var i = 0; i < polygonGeo.rings.length; i++) { for (var p = 0; p < polygonGeo.rings[i].length; p++) { var LatLon = String(polygonGeo.rings[i][p]); console.log(LatLon); } }

All this does it outputs it as:

16816274.629485022,-4041754.114785292,16822695.33986097,-4041754.114785292,16822695.33986097,-4045050.461630086,16816274.629485022,-4045050.461630086

How can i get to convert it to Lat and Long?

Re: Getting Polygon points as Lat and Lon

SiyabongaKubeka — Thu, 02 Jun 2022 10:59:34 GMT

Hi @Aeseir , remember, you are drawing a polygon and a polygon has multiple vertices, to this output is a longitude and latitude of each vertex (corner). You can try using WebmercatorUtils to convert the geometry to Geographic .

Re: Getting Polygon points as Lat and Lon

Aeseir — Thu, 02 Jun 2022 11:02:10 GMT

What would this look like for this example then?

Re: Getting Polygon points as Lat and Lon

SiyabongaKubeka — Thu, 02 Jun 2022 11:12:19 GMT

Something like this

Also do not forget to add WebmercatorUtils on your require statements and function statements

for (var i = 0; i < gra.geometry.rings.length; i++) {
                  for (var p = 0; p < gra.geometry.rings[i].length; p++) {
                    var pnt = gra.geometry.getPoint(i, p);
                    crmLatitude = String(pnt.latitude);
                    crmLongitude = String(pnt.longitude);
                    var LatLon = String(pnt);
                    console.log(LatLon);
                    console.log(crmLatitude);
                    console.log(crmLongitude);
                    latlon = LatLon;
                  }

Re: Getting Polygon points as Lat and Lon

Aeseir — Thu, 02 Jun 2022 11:42:21 GMT

Interesting approach, any advice on how to reverse the process?

I just discovered webMercatorUtils.xyToLngLat as well

Re: Getting Polygon points as Lat and Lon

ReneRubalcava — Thu, 02 Jun 2022 12:15:47 GMT

I have a utility that might help too if you don't want to manually pull vertices out, will convert polygons to points you can pull lat/lon off too. https://github.com/odoe/explode