topic Re: Get coordinate count only in ArcGIS API for Silverlight Questions

Get coordinate count only

BradBarnell — Sun, 17 Apr 2011 23:11:40 GMT

I there a way to get only the coordinate count or size of a feature with the one of the ESRI tasks? I have some very large polygons that hang-up my application when a user tries to download and highlight the geometry.

Re: Get coordinate count only

JenniferNery — Sat, 11 Dec 2021 13:45:12 GMT

As far as I know there is no query that can give you this. When you perform a query task with ReturnGeometry=True, you get the shape of the geometry. You may perform Linq query on this result. For example:

var largest = e.FeatureSet.Features.Max(g => g.Geometry.GetArea());
var graphic = e.FeatureSet.Features.FirstOrDefault(g => g.Geometry.GetArea() == largest);

However, this is not very efficient and the result may not be correct. A diagonal polyline's extent is not necessarily its true area. Also the number of vertices does not always guarantee that it will be the largest polygon.

public static class GeometryExtension
{
 public static double GetArea(this Geometry geom)
 {
  if (geom == null || geom.Extent == null) return 0;
  return geom.Extent.Height * geom.Extent.Width;
 }

 public static int GetVerticesCount(this Geometry geom)
 {
  if (geom is Polygon)
  {
   Polygon polygon = geom as Polygon;
   if (polygon.Rings == null) return 0;
   int count = 0;
   foreach (var pc in polygon.Rings)
    count += pc.Count;
   return count;
  }
  return 0;
 }
}

Re: Get coordinate count only

DominiqueBroux — Tue, 26 Apr 2011 13:47:11 GMT

From ArcGIS server 10.0 you can also use the maxAllowableOffset option which can be used for generalizing geometries returned by a query, an identify or a find task.

Re: Get coordinate count only

AnastasiaAourik — Thu, 31 May 2012 18:18:29 GMT

On a slight tangent, I do not see Return Count Only available via the Tasks.Query Class.
I have version 2.2.0.629

I see only ReturnIdsOnly and ReturnGeometry, but I cannot set ReturnCountOnly via the ArcGIS api for silverlight.

What gives???

Re: Get coordinate count only

DominiqueBroux — Fri, 01 Jun 2012 06:21:12 GMT

On a slight tangent, I do not see Return Count Only available via the Tasks.Query Class.

The method is called ExecuteCountAsync.
It is available from SLAPI 2.1 but needs ArcGIS Server 10.0 SP1 to work.