ArcGIS Pro 3.1 API Reference Guide
ArcGIS.Core.Geometry Namespace / IGeometryEngine Interface / ConvexHull Method
The geometry to create a convex hull of.
Example

In This Topic
    ConvexHull Method (IGeometryEngine)
    In This Topic
    Constructs the convex hull of the geometry.
    Syntax
    Geometry ConvexHull( 
       Geometry geometry
    )
    Function ConvexHull( _
       ByVal geometry As Geometry _
    ) As Geometry

    Parameters

    geometry
    The geometry to create a convex hull of.

    Return Value

    A geometry that represents the convex hull of the input geometry.
    Exceptions
    ExceptionDescription
    Geometry is null or empty.
    The method is not implemented for GeometryBag.
    Remarks
    The convex hull of a geometry is the minimal bounding polygon such that all outer angles are convex. The ConvexHull of a point is the point itself.

    GeometryEngine ConvexHull

    Example
    Determine convex hull
    //
    // convex hull around a point - returns a point
    //
    
    MapPoint pt = MapPointBuilderEx.CreateMapPoint(2.0, 2.0);
    Geometry hull = GeometryEngine.Instance.ConvexHull(pt);
    MapPoint hullPt = hull as MapPoint;
    // nullPt.X = 2
    // hullPt.Y = 2
    
    
    List<MapPoint> list = new List<MapPoint>();
    list.Add(MapPointBuilderEx.CreateMapPoint(1.0, 1.0));
    list.Add(MapPointBuilderEx.CreateMapPoint(1.0, 2.0));
    list.Add(MapPointBuilderEx.CreateMapPoint(2.0, 2.0));
    list.Add(MapPointBuilderEx.CreateMapPoint(2.0, 1.0));
    
    //
    // convex hull around a multipoint - returns a polygon
    //
    
    // build a multiPoint
    Multipoint multiPoint = MultipointBuilderEx.CreateMultipoint(list);
    
    hull = GeometryEngine.Instance.ConvexHull(multiPoint);
    Polygon hullPoly = hull as Polygon;
    // hullPoly.Area = 1
    // hullPoly.PointCount = 5
    
    // 
    // convex hull around a line - returns a polyline or polygon
    // 
    
    List<MapPoint> polylineList = new List<MapPoint>();
    polylineList.Add(MapPointBuilderEx.CreateMapPoint(1.0, 1.0));
    polylineList.Add(MapPointBuilderEx.CreateMapPoint(2.0, 2.0));
    
    // 2 point straight line
    Polyline polyline = PolylineBuilderEx.CreatePolyline(polylineList);
    hull = GeometryEngine.Instance.ConvexHull(polyline);
    Polyline hullPolyline = hull as Polyline;
    // hullPolyline.Length = Math.Sqrt(2)
    // hullPolyline.PointCount = 2
    
    // 3 point angular line
    polylineList.Add(MapPointBuilderEx.CreateMapPoint(2.0, 1.0));
    polyline = PolylineBuilderEx.CreatePolyline(polylineList);
    hull = GeometryEngine.Instance.ConvexHull(polyline);
    hullPoly = hull as Polygon;
    // hullPoly.Length = 2 + Math.Sqrt(2)
    // hullPoly.Area = 0.5
    // hullPoly.PointCount = 4
    
    //
    // convex hull around a polygon - returns a polygon
    //
    
    // simple polygon
    Polygon poly = PolygonBuilderEx.CreatePolygon(list);
    hull = GeometryEngine.Instance.ConvexHull(poly);
    hullPoly = hull as Polygon;
    
    // hullPoly.Length = 4.0
    // hullPoly.Area = 1.0
    // hullPoly.PointCount = 5
    
    // polygon with concave angles
    List<MapPoint> funkyList = new List<MapPoint>();
    funkyList.Add(MapPointBuilderEx.CreateMapPoint(1.0, 1.0));
    funkyList.Add(MapPointBuilderEx.CreateMapPoint(1.5, 1.5));
    funkyList.Add(MapPointBuilderEx.CreateMapPoint(1.0, 2.0));
    funkyList.Add(MapPointBuilderEx.CreateMapPoint(2.0, 2.0));
    funkyList.Add(MapPointBuilderEx.CreateMapPoint(1.5, 1.5));
    funkyList.Add(MapPointBuilderEx.CreateMapPoint(2.0, 1.0));
    funkyList.Add(MapPointBuilderEx.CreateMapPoint(1.0, 1.0));
    
    Polygon funkyPoly = PolygonBuilderEx.CreatePolygon(funkyList);
    hull = GeometryEngine.Instance.ConvexHull(funkyPoly);
    hullPoly = hull as Polygon;
    // hullPoly.Length = 4.0
    // hullPoly.Area = 1.0
    // hullPoly.PointCount = 5
    // hullPoly.Points[0] = 1.0, 1.0
    // hullPoly.Points[1] = 1.0, 2.0
    // hullPoly.Points[2] = 2.0, 2.0
    // hullPoly.Points[3] = 2.0, 1.0
    // hullPoly.Points[4] = 1.0, 1.0
    Requirements

    Target Platforms: Windows 11, Windows 10

    ArcGIS Pro version: 3.0 or higher.
    See Also