GeodesicBuffer(Geometry,Double) Method

In This Topic

Creates a buffer polygon at the specified geodesic distance around the given geometry.

Syntax

C#
Visual Basic (Declaration)

public Geometry GeodesicBuffer( 
   Geometry geometry,
   double distance
)

Public Overloads Function GeodesicBuffer( _
   ByVal geometry As Geometry, _
   ByVal distance As Double _
) As Geometry

Parameters

geometry: The input geometry. Cannot be null and its spatial reference cannot be null.
distance: The distance (in meters) to buffer the geometry.

Return Value

A geometry representing the buffered area.

Exceptions

Exception	Description
System.ArgumentNullException	Geometry is null or empty. Or geometry's spatial reference is null.
System.NotImplementedException	The method is not implemented for GeometryBag.
System.ArgumentException	Geometry has no spatial reference.
System.ArgumentException	The buffer distance must be a valid floating point number.
System.NotImplementedException	Spatial reference of geometryis an image coordinate system.

Remarks

Geodesic distance is the shortest distance between two points on the surface of the Earth.

If the buffer distance is zero and the input geometry is a polygon or an envelope, then a polygon created from the input geometry is returned.

If the distance is less than or equal to zero and the input geometry is not a polygon or an envelope, then an empty polygon is returned.

Example

Create a buffer polygon at the specified geodesic distance

// buffer a point
MapPoint pt = MapPointBuilderEx.CreateMapPoint(1.0, 1.0, SpatialReferences.WGS84);
Polygon outPolygon = GeometryEngine.Instance.GeodesicBuffer(pt, 5) as Polygon;

double delta = SpatialReferences.WGS84.XYTolerance * 2 * Math.Sqrt(2);
ReadOnlyPointCollection points = outPolygon.Points;
foreach (MapPoint p in points)
{
  double d = GeometryEngine.Instance.GeodesicDistance(pt, p);
  // d = 5 (+- delta)
}

// specify a unit for the distance
outPolygon = GeometryEngine.Instance.GeodesicBuffer(pt, 5000, LinearUnit.Millimeters) as Polygon;

// buffer of 0 distance produces an empty geometry
Geometry g = GeometryEngine.Instance.GeodesicBuffer(pt, 0);
// g.IsEmpty = true

// buffer many points
List<MapPoint> list = new List<MapPoint>();
list.Add(MapPointBuilderEx.CreateMapPoint(1.0, 1.0, SpatialReferences.WGS84));
list.Add(MapPointBuilderEx.CreateMapPoint(10.0, 20.0));
list.Add(MapPointBuilderEx.CreateMapPoint(40.0, 40.0));
list.Add(MapPointBuilderEx.CreateMapPoint(60.0, 60.0));

outPolygon = GeometryEngine.Instance.GeodesicBuffer(list, 10000) as Polygon;
// outPolygon.PartCount = 4

// buffer different geometry types
List<Coordinate2D> coords = new List<Coordinate2D>()
{
  new Coordinate2D(1, 2), new Coordinate2D(10, 20), new Coordinate2D(20, 30),
  new Coordinate2D(50, 60), new Coordinate2D(70, 80), new Coordinate2D(80, 40),
  new Coordinate2D(90, 10), new Coordinate2D(110, 15), new Coordinate2D(120, 30),
  new Coordinate2D(10, 40), new Coordinate2D(-10, 40), new Coordinate2D(-10, 50)
};

List<Geometry> manyGeometries = new List<Geometry>
{
  MapPointBuilderEx.CreateMapPoint(1.0, 1.0, SpatialReferences.WGS84),
  PolylineBuilderEx.CreatePolyline(new List<Coordinate2D>(){coords[0], coords[1], coords[2]}, SpatialReferences.WGS84),
  PolylineBuilderEx.CreatePolyline(new List<Coordinate2D>(){coords[3], coords[4], coords[5]}),
  PolygonBuilderEx.CreatePolygon(new List<Coordinate2D>(){coords[9], coords[10], coords[11]})
};

outPolygon = GeometryEngine.Instance.GeodesicBuffer(manyGeometries, 20000) as Polygon;

// specify unit types
outPolygon = GeometryEngine.Instance.GeodesicBuffer(manyGeometries, 20, LinearUnit.Miles) as Polygon;

Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

Reference

GeometryEngine Class
GeometryEngine Members
Overload List

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