[GIS] VB.net Converting UTM to Lat/Lon (State Plane with WKID) – ArcGis

arcgis-runtimecoordinatesvb.net

I have looked at many libraries. Many simply don't work, others are very poorly documented.

I have a very long list of X/Y coordinates (US FT) and an associated WKID. I am trying to convert that to Lat/Lon format for mapping.

Can anyone suggest routes for completing this process in vb.net?

(the closest I've come to success is finding the esri.arcgisruntime.geometry.ProjectionConverter.convert – This seems to give me the option to suggest a wkid, x & y coord… but It's poorly documented and, unfortunately, I can't get it to do any conversions)

    Dim wkid as integer= 102100
    Dim ref As New Esri.ArcGISRuntime.Geometry.SpatialReference(wkid)
    Dim converter = New Esri.ArcGISRuntime.Geometry.ProjectionConverter()
    Dim mappoint = New Esri.ArcGISRuntime.Geometry.MapPoint(-9638404.7886215933, 3990218.2857465576, ref)
    Dim typ As Type = GetType(Esri.ArcGISRuntime.Geometry.MapPoint)
    Dim glob As New Globalization.CultureInfo("en")
    Dim result = converter.Convert(mappoint, typ, wkid, glob)

FYI, if there are some arcgis account auth required, I do not have that.

Best Answer

For those interested I've managed to get this working, I'm converting from MGA meters to a local map grid projection, also in meters.

private Esri.ArcGISRuntime.Geometry.MapPoint ConvertToLocalMapGridCoords(Esri.ArcGISRuntime.Geometry.MapPoint sourceMapPoint, string projectionFile)
{
    var wkTextDest = System.IO.File.ReadAllText(projectionFile);

    var projectionConverter = new Esri.ArcGISRuntime.Geometry.ProjectionConverter();
    var result = projectionConverter.Convert(sourceMapPoint, typeof(MapPoint), wkTextDest, System.Globalization.CultureInfo.InvariantCulture);

    return (Esri.ArcGISRuntime.Geometry.MapPoint)result;
}

I'm calling it using: (You will most likely be doing something completely different here!)

const int wkidSource = 102100;
var coordPoint = newMapControl.ScreenPointToCoordPoint(e.Location);

var mouseMapPoint = Esri.ArcGISRuntime.Geometry.ConvertCoordinate.FromDecimalDegrees(string.Format("{0},{1}", coordPoint.GetY(), coordPoint.GetX()), new Esri.ArcGISRuntime.Geometry.SpatialReference(wkidSource));

var convertedMapPoint = ConvertToLocalMapGridCoords(mouseMapPoint, @"C:\abc\xyz.prj");

I'm creating a spacial reference from a well known text (ESRI Projection File .prj).

Note: coordPoint.GetY(), coordPoint.GetX() are just Decimal latitudes and longitudes respectively.

Related Solutions

[GIS] Coordinate conversion – Lat Long to State Plane, ArcServer-Silverlight

You can use the ArcGIS Server REST API out-of-the-box Geometry Service, which has a Project operation, to project a coordinate pair, and then create a graphic from it. The Geometry Service is included in the ESRI Silverlight API as the GeometryService class.

If you haven't your own ArcGIS Server, perhaps you can try the ESRI-published sample servers.

Example class hacked out of one of mine:

using System;
using System.Net;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Geometry;
using ESRI.ArcGIS.Client.Tasks;
using System.Collections.Generic;

namespace YabaDabaDoo
{
  /// <summary>
  /// A Service for projecting a point to another coordinate system
  /// and return its coordinates. This service can only operate on
  /// points.
  /// </summary>
  public class ProjectionService
  {
    #region Private/Protected Fields
    private GeometryService _gService = null;
    private SpatialReference _tosr = null;
    #endregion

    public ProjectionService(string gserveUrl, int toSrid)
    {     
      //gserveUrl should be like: http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer
      //if you don't know your SRID, check the lists at: http://resources.arcgis.com/en/help/rest/apiref/usingspatialreferences.html
      _gService = new GeometryService(gserveUrl);
      _tosr = new SpatialReference(toSrid);
      _gService.ProjectCompleted += new EventHandler<GraphicsEventArgs>(_gService_ProjectCompleted);
      _gService.Failed += new EventHandler<TaskFailedEventArgs>(_gService_Failed);
    }

    /// <summary>
    /// This does the real work of the service. In this case, the input SR is that of the graphic.
    /// </summary>
    public void ProjectPoint(Graphic editGraphic)
    {
      try
      {
        //check that the geometry is a point
        if (editGraphic.Geometry is MapPoint)
        {
          _gService.ProjectAsync(new List<Graphic>() { new Graphic() { Geometry = Geometry.Clone(editGraphic.Geometry) } }, _tosr);
        }
        else
        {
          // can't do this
        }
      }
      catch (Exception e)
      {
        //TODO: do something sensible
      }
    }
    #endregion

    #region Private/Protected methods - GeometryService event handlers
    void _gService_ProjectCompleted(object sender, GraphicsEventArgs e)
    {
      MapPoint p = e.Results[0].Geometry as MapPoint;

      //TODO: do something with p
    }

    private void _gService_Failed(object sender, TaskFailedEventArgs e)
    {
      //TODO: do something sensible
    }
    #endregion
  }
}

[GIS] KD-Tree implementation with lat/lon coordinates

How are you defining these "Euclidean distances"? Just using lat-long as x-y cartesian coordinates? That will work fairly well for small areas but at some point you have to realise that the X-coordinates are getting closer together at the poles.

If I'm standing two metres from the north pole my feet could be at maybe 30W and 30E (perhaps I do the splits...), which is 60 angular degree units apart in cartesian lat-long. But the north pole is only some tiny fraction of a degree unit in front of my feet. A euclidean distance algorithm would think my feet are thousands of times further apart than the distance from my feet to the pole.

Yes its extreme up here with the polar bears, but the spherical earth can muck up your distance calculations anywhere except on the equator.

Transform to a reasonable cartesian coordinate system if your data is in a small area, or use the full spherical distance.

Best Answer

Related Solutions

[GIS] Coordinate conversion – Lat Long to State Plane, ArcServer-Silverlight

[GIS] KD-Tree implementation with lat/lon coordinates

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