nav[aria-label="Primary Navigation"] { padding: 0; & ul { list-style: none; width: 100%; display: flex; flex-direction: row; justify-content: start; align-items: start; gap: 30px; padding: 0; & li { margin: 0; } & ul li { list-style: none; } } }

Converting coordinates

GeorgeFaraj

I am listening to the OnMouseDown event of my IMapControl4, and the IMapControlEvents2_OnMouseDownEvent provides a mapX and mapY. How do I convert this coordinate to WGS84? I need to interface with another 3rd party library that requires WGS84 coordinates as its input.

Thanks,
George Faraj

Vind meer berichten getagd met

Accepted answers

NeilClemmons_GISinc

You need to project the data to that coordinate system. The map x, y passed into the event are in whatever coordinate system the map is in, so just create a new point object, give it the same spatial reference as the map and set the x, y properties. Then call Project and pass in the spatial reference you want to project it to. You can get this spatial reference object from ISpatialReferenceFactory.CreateGeographicCoordinateSystem. After calling Project, the x, y properties will have the updated coordinates.

All comments

ΣταυρούλαΓιαννακοπούλου

Good morning everyone! I would like to ask if there is a way to define my coordinates, taking into account that I don't know their coordinates system. Is there a way to determine it? All I have is an xls file. Thank you very much for your collaboration!

GeorgeFaraj

Alright, so I think I have the correct coordinates in degrees now. Thanks a lot!

NeilClemmons_GISinc

Without knowing what your original coordinate system and coordinates are I can't tell you if those values are correct or not. The results you're getting will be in decimal degrees since you are projecting into a geographic coordinate system. Remember that when expressed as x, y coordinates of a point that x = longitude and y = latitude. Longitude values range from 0 to 180 with positive values being measured East and negative values being measured West. Latitude values range from 0 to 90 with positive values being measured North and negative values being measured South. The coordinates you posted are near Vancouver, Canada.

GeorgeFaraj

Thank you Neil. That helped. I wrote the following method:

public static IPoint GetLatLngPointsFromMapPoints(this IActiveView view, IMapControl4 map, double controlX, double controlY)
{
 var mapPoint = new PointClass();
 mapPoint.SpatialReference = map.SpatialReference;
 mapPoint.PutCoords(controlX, controlY);

 if (mapPoint.SpatialReference.Name == "Unknown")
 {
  mapPoint.SpatialReference = view.ScreenDisplay.DisplayTransformation.ToMapPoint(0, 0).SpatialReference;
 }
 if (double.IsNaN(mapPoint.Z))
 {
  mapPoint.Z = 0;
 }

 if (mapPoint.SpatialReference.Name == "Unknown")
 {
  return null;
 }

 var spatialRefFactory = new SpatialReferenceEnvironment();
 var geoCoordSystem = spatialRefFactory.CreateGeographicCoordinateSystem((int)esriSRGeoCSType.esriSRGeoCS_WGS1984);
 mapPoint.Project(geoCoordSystem);
 return mapPoint;
}

And I'm getting values like -122.545187727749 and 45.6971389559235. Not sure if these are degrees or if they are just incorrect. Does this sound right to you?

NeilClemmons_GISinc

Doe mee aan het gesprek

Aangemelde leden kunnen berichten plaatsen, updates volgen en meer. Nieuw hier? Registreer een gratis account.

Snelle Links

Community Help
Find useful guides, FAQs, and documents to help you navigate and make the most of Esri Community.