SpatialReference sr = SpatialReferences.WGS84; MapPoint pt = MapPointBuilder.CreateMapPoint(10, -4.1, sr); List<Coordinate2D> coords = new List<Coordinate2D>() { new Coordinate2D(10, 1), new Coordinate2D(10, -4), new Coordinate2D(0, -4), new Coordinate2D(0, 1), new Coordinate2D(10, 1) }; Polygon polygon = PolygonBuilder.CreatePolygon(coords, sr); // find the nearest point in the polygon geomtry to the pt ProximityResult result = GeometryEngine.Instance.NearestPoint(polygon, pt); // result.Point = 5, 1 // result.SegmentIndex = 3 // result.PartIndex = 0 // result.PointIndex = null //result.Distance = 4 //result.RightSide = false // find the nearest vertex in the polgyon geometry to the pt result = GeometryEngine.Instance.NearestVertex(polygon, pt); // result.Point = 10, 1 // result.PointIndex = 0 // result.SegmentIndex = null // result.PartIndex = 0 // result.Distance = Math.Sqrt(41) // result.RightSide = false