topic Re: Find the length of sides of a polygon in ArcGIS JavaScript Maps SDK Questions

Find the length of sides of a polygon

cadgism — Tue, 27 Oct 2020 09:02:35 GMT

Hi All Greetings

How can I find the length of sides of a polygon ( Not Perimeter of the polygon). Is the following right approach or is there any simpler approach please ?

1. find the number of rings in the polygon

2. loop through them

3. calculate length from the start point to end point

Thank you

Re: Find the length of sides of a polygon

RobertScheitlin__GISP — Tue, 27 Oct 2020 13:01:27 GMT

Almost. Each ring represents its own closed polygon, not a side of a polygon. So once you have the ring (by looping through the rings) you then get the rings points

Each ring is made up of three or more points.

You can use the getPoint method of the polygon class to get the specific point.

https://developers.arcgis.com/javascript/3/jsapi/polygon-amd.html#getpoint

Then make a new Polyline from two points (i.e ring 0 point 0 and point 1) and use that new polyline in the geodesic or planar length method.

Re: Find the length of sides of a polygon

cadgism — Sun, 12 Dec 2021 02:07:23 GMT

Thanks. This is what I think I am doing. But keep getting error : "The operation cannot be performed on a non-simple geometry."

function graphicDimension(resultGraphic) {
    require(["esri/geometry/Polyline",
        "esri/tasks/support/LengthsParameters", "esri/tasks/GeometryService", "esri/geometry/Point"],
        function (Polyline, LengthsParameters, GeometryService, Point) {

          for (i = 0; i < resultGraphic.geometry.rings.length; i++) { // value 1 polygon

              for (j = 0; j < resultGraphic.geometry.rings[i].length; j++) { //value 6 points

                  fromPoint = new Point (resultGraphic.geometry.rings[i][j]);
                  toPoint = new Point( resultGraphic.geometry.rings[i][j + 1]);

                  //console.log(fromPoint, toPoint);

                 paths = [
                            [fromPoint.x, fromPoint.y],
                            [toPoint.x, toPoint.y]
                    ]

                polyLine = new Polyline({
                    paths: [paths],
                    spatialReference: app.view.spatialReference
                });

                lengthParams = new LengthsParameters();
                lengthParams.calculationType = "geodesic";
                lengthParams.geodesic = true;
                lengthParams.polylines = [polyLine];
                lengthParams.lengthUnit = "METER"; 

                geomSerVice = new GeometryService(geometryServiceUrl);
                geomSerVice.lengths(lengthParams, function (result) {
                    console.log(result.lengths[0]);
                    alert("length");
                });  

                // debugger; 
             }
        } 
            
           
    });
};‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Find the length of sides of a polygon

RobertScheitlin__GISP — Wed, 28 Oct 2020 12:17:01 GMT

That tells me that you have to run the geometry through the simplify method first then.

https://developers.arcgis.com/javascript/3/jsapi/esri.geometry.geometryengine-amd.html#simplify

Re: Find the length of sides of a polygon

cadgism — Fri, 30 Oct 2020 19:48:38 GMT

Thank you again, Still did not work . I used the traditional way to find out the length of a line

√((x_2-x_1)²+(y_2-y_1)²)‍