topic Re: How to get the centroid of a "C" or "U" shape like polygon? in Java Maps SDK Questions

How to get the centroid of a "C" or "U" shape like polygon?

Joo_PinTan — Fri, 16 Sep 2016 02:15:05 GMT

Anyone know how to get the centroid of a "C", or "U" shape like polygon and the point need to be inside the polygon some where near the centre?

Re: How to get the centroid of a "C" or "U" shape like polygon?

DanPatterson_Retired — Fri, 16 Sep 2016 06:55:40 GMT

in most Arc* products this is referred to as a LabelPoint, so look for some incarnation of that term

The point at which the label is located. The labelPoint is always located within or on a feature.

Re: How to get the centroid of a "C" or "U" shape like polygon?

JayantaPoddar — Fri, 16 Sep 2016 07:36:57 GMT

In Feature to Point Tool, choose "INSIDE" as the point location.

Re: How to get the centroid of a "C" or "U" shape like polygon?

Joo_PinTan — Fri, 16 Sep 2016 08:50:04 GMT

I need to use ArcGis Runtime SDK for Java API to code it. Feature to point is not available for me.

Re: How to get the centroid of a "C" or "U" shape like polygon?

JayantaPoddar — Fri, 16 Sep 2016 09:12:20 GMT

Oops... My mistake. Didn't notice the Space where it's posted.

Re: How to get the centroid of a "C" or "U" shape like polygon?

DanPatterson_Retired — Fri, 16 Sep 2016 10:49:01 GMT

did you look for labelpoint or not? it would be in a polygon class or methods section for your api

Re: How to get the centroid of a "C" or "U" shape like polygon?

JoshuaBixby — Fri, 16 Sep 2016 15:10:14 GMT

For the Java API, getLabelPointForPolygon in the GeometryEngine class.

Re: How to get the centroid of a "C" or "U" shape like polygon?

DanPatterson_Retired — Fri, 16 Sep 2016 17:14:13 GMT

like I said Joshua... they have to look for labelpoint stuff ... grief

Re: How to get the centroid of a "C" or "U" shape like polygon?

Joo_PinTan — Sat, 11 Dec 2021 23:32:07 GMT

protected boolean determineCentroid(Geometry polygon, Point centroid) {
  if (polygon.getType() == Geometry.Type.POLYGON) {
    Point tempCentroid;

    //Get centroid of the polygon
    Envelope env = new Envelope();
    polygon.queryEnvelope(env);
    tempCentroid = env.getCenter();

    //If tempCentroid is within the polygon then centroid is valid, else look for nearest vertex
    if (GeometryEngine.within(polygon, tempCentroid, featureServiceTable.getSpatialReference()))
      centroid.setXY(tempCentroid.getX(), tempCentroid.getY());
    else {
      Proximity2DResult proximity2DResult = GeometryEngine.getNearestCoordinate(polygon, tempCentroid, true);
      centroid.setXY(proximity2DResult.getCoordinate().getX(), proximity2DResult.getCoordinate().getY());
    }

    return true;
  }
  
  return false;
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

I did something as shown above to look for the centroid of a polygon whereby the centre is empty. Although the result it is not really plotted at the "centre" of the polygon but it did solved my problem.