The function returns a piecewise approximation of a geodesic ellipse (or geodesic circle, if semiAxis1Length = semiAxis2Length). Constructs a geodesic ellipse centered on the specified point. If this method is used to generate a polygon or a polyline, the result may have more than one part, depending on the size of the ellipse and its position relative to the horizon of the coordinate system. When the method generates a polyline or a multipoint, the result vertices lie on the boundary of the ellipse. When a polygon is generated, the interior of the polygon is the interior of the ellipse, however the boundary of the polygon may contain segments from the spatial reference horizon, or from the GCS extent.

Public Function GeodesicEllipse( _
   ByVal parameter As GeodesicEllipseParameter, _
   ByVal spatialReference As SpatialReference _
) As Geometry

public Geometry GeodesicEllipse( 
   GeodesicEllipseParameter parameter,
   SpatialReference spatialReference
)

{
  GeodesicEllipseParameter param = new()
  {
    AxisDirection = 4 * Math.PI / 3,
    Center = new Coordinate2D(-120, 60),
    LinearUnit = LinearUnit.Meters,
    OutGeometryType = GeometryType.Polyline,
    SemiAxis1Length = 6500000,
    SemiAxis2Length = 1500000,
    VertexCount = 800
  };

  Geometry geometry = GeometryEngine.Instance.GeodesicEllipse(param, SpatialReferences.WGS84);
  // geometry.IsEmpty = false

  polyline = geometry as Polyline;
  // polyline.PointCount = 801
  // polyline.PartCount = 1
}