NearestPoint Method (IGeometryEngine)

In This Topic

Finds the nearest point in the geometry to a specified point.

Syntax

Visual Basic (Declaration)
C#

Function NearestPoint( _
   ByVal geometry As Geometry, _
   ByVal point As MapPoint _
) As ProximityResult

ProximityResult NearestPoint( 
   Geometry geometry,
   MapPoint point
)

Parameters

geometry: The geometry.
point: The point to which the returned point will be nearest.

Return Value

ProximityResult.

If the input geometry is a non-empty point, then ProximityResult.PointIndex = 0, ProximityResult.PartIndex = 0, and ProximityResult.SegmentIndex is null.

If the input geometry is a non-empty multipoint, ProximityResult.PointIndex is the index of the nearest point in the Multipoint, ProximityResult.PartIndex = ProximityResult.PointIndex, and ProximityResult.SegmentIndex is null.

Otherwise, if the input geometry is non-empty, then ProximityResult.PointIndex is null and ProximityResult.SegmentIndex is the segment which contains the nearest point. The segment index is relative to the ProximityResult.PartIndex. For example, if the segment index = 0 and the part index = 2, then the segment containing the nearest point is segment 0 of part 2. In other words, the segment is the first segment of the third part.

ProximityResult.RightSide specifies if the input query point is on the right side of the input geometry or not.

If either of the input geometries are empty, then ProximityResult.Distance = -1, ProximityResult.Point is empty, ProximityResult.RightSide = false, ProximityResult.PartIndex = -1, ProximityResult.PointIndex is null, and ProximityResult.SegmentIndex = null.

Exceptions

Exception	Description
System.ArgumentNullException	Either geometry or point or both are null.
System.NotImplementedException	The method is not implemented for GeometryBag.
System.NotImplementedException	This function is not implemented for envelopes.

Remarks

The nearest point does not have to be a vertex of the input geometry. It can be any point on the geometry. If the geometry is a Polygon, then the nearest point will be a point on the boundary of the Polygon.

GeometryEngine NearestPoint

Example

Nearest Point versus Nearest Vertex

{
  SpatialReference sr = SpatialReferences.WGS84;
  MapPoint pt = MapPointBuilderEx.CreateMapPoint(5, 5, sr);

  List<Coordinate2D> coords =
  [
    new Coordinate2D(10, 1),
  new Coordinate2D(10, -4),
  new Coordinate2D(0, -4),
  new Coordinate2D(0, 1),
  new Coordinate2D(10, 1)
  ];

  polygon = PolygonBuilderEx.CreatePolygon(coords);

  // find the nearest point in the polygon geometry 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
}

Requirements

Target Platforms: Windows 11 Home, Pro, Enterprise (64 bit)

ArcGIS Pro version: 3.0 or higher.

Reference

IGeometryEngine Interface
IGeometryEngine Members

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