ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Core.Geometry Namespace / IGeometryEngine Interface / QueryNormal Method / QueryNormal(Multipart,SegmentExtensionType,Double,AsRatioOrLength,Double) Method
The multipart to which the tangent line is constructed.
Specifies the extension method that determines the direction and position of the tangent line.
Specifies the distance along the segment from which the tangent line and normal line are constructed.
Determines whether the distanceAlongCurve is returned as a ratio of the segment length or as length from the start point.
Specifies the length of the returned normal line.
Example

In This Topic
    QueryNormal(Multipart,SegmentExtensionType,Double,AsRatioOrLength,Double) Method
    In This Topic
    Constructs a line normal to a segment from a point at a specified distance along the segment.
    Syntax
    Polyline QueryNormal( 
   Multipart multipart,
   SegmentExtensionType extensionType,
   double distanceAlongCurve,
   AsRatioOrLength asRatioOrLength,
   double normalLength
)
    Overloads Function QueryNormal( _
   ByVal multipart As Multipart, _
   ByVal extensionType As SegmentExtensionType, _
   ByVal distanceAlongCurve As Double, _
   ByVal asRatioOrLength As AsRatioOrLength, _
   ByVal normalLength As Double _
) As Polyline

    Parameters

    multipart
    The multipart to which the tangent line is constructed.
    extensionType
    Specifies the extension method that determines the direction and position of the tangent line.
    distanceAlongCurve
    Specifies the distance along the segment from which the tangent line and normal line are constructed.
    asRatioOrLength
    Determines whether the distanceAlongCurve is returned as a ratio of the segment length or as length from the start point.
    normalLength
    Specifies the length of the returned normal line.

    Return Value

    Polyline representing the normal line.
    Exceptions
    ExceptionDescription
    System.ArgumentNullExceptionmultipartis null or empty.
    System.NotImplementedExceptionSpatial reference of multipartis an image coordinate system.
    Remarks
    A normal line at a point on a curve is perpendicular to the tangent line at that point. The distanceAlongCurve parameter can be negative, and it can be larger than the length of the segment. The extensionType parameter is ignored if distanceAlongCurve is greater than zero and less than the length of the segment. For example, shown below in blue is an elliptic arc segment with its start point in green and end point in red. The orange tangent line is constructed halfway along the curve and the extensionType parameter is ignored. The purple line is the normal line.

    QueryNormal NoExtension

    If distanceAlongCurve is less than zero, then the tangent line is embedded in an extension from the start point of the segment. If distanceAlongCurve is greater than the length of the input segment, then the tangent line is embedded in an extension from the end point of the segment. In the following example, distanceAlongCurve = 1.2, asRatioOrLength = AsRatioOrLength.AsRatio, and extensionType = SegmentExtensionType.ExtendTangentAtTo. Note that if asRatioOrLength = AsRatioOrLength.AsRatio, then the length of the input segment is 1. The extended tangent segment is the gray dashed line and is 0.2 * length of the input segment. The constructed tangent is in orange, and the normal line is in purple.

    QueryNormal TangentAtTo

    SegmentExtensionType.ExtendEmbeddedAtTo, SegmentExtensionType.ExtendEmbeddedAtFrom, and SegmentExtensionType.ExtendEmbedded when applied to an elliptic arc segment refer to the embedded ellipse or circle. Shown below in blue is an elliptic arc segment that is circular along with its embedded circle in gray.

    QueryNormal Embedded Circle

    Here is an example where distanceAlongCurve = 1.2, asRatioOrLength = AsRatioOrLength.AsRatio, and extensionType = SegmentExtensionType.ExtendEmbeddedAtTo.

    QueryNormal EmbeddedAtTo

    If the input segment is not an elliptic arc segment, then SegmentExtensionType.ExtendEmbeddedAtTo, SegmentExtensionType.ExtendEmbeddedAtFrom, and SegmentExtensionType.ExtendEmbedded are equivalent to SegmentExtensionType.ExtendTangentAtTo, SegmentExtensionType.ExtendTangentAtFrom, and SegmentExtensionType.ExtendTangent respectively. There are cases when the tangent cannot be extended as specified by the extensionType parameter.For example, if the distanceAlongCurve is negative and extensionType = SegmentExtensionType.ExtendTangentAtTo.In this case, the tangent line is constructed at the start point of the input segment.Similarly, if the distanceAlongCurve is greater than the length of the input segment and extensionType = SegmentExtensionType.ExtendTangentAtFrom, then the tangent line is constructed at the end point of the input segment.

    Example
    QueryNormal
    string json = "{\"curvePaths\":[[[-13046586.8335,4036570.6796000004]," +
              "{\"c\":[[-13046645.107099999,4037152.5873000026]," +
              "[-13046132.776277589,4036932.1325614937]]}]],\"spatialReference\":{\"wkid\":3857}}";
Polyline polyline = PolylineBuilderEx.FromJson(json);

EllipticArcSegment arc = polyline.Parts[0][0] as EllipticArcSegment;

// No extension, distanceAlongCurve = 0.5

// use the polyline
Polyline poly_normal = GeometryEngine.Instance.QueryNormal(polyline, SegmentExtensionType.NoExtension, 0.5, AsRatioOrLength.AsRatio, 1000);
// or a segment
LineSegment seg_normal = GeometryEngine.Instance.QueryNormal(arc, SegmentExtensionType.NoExtension, 0.5, AsRatioOrLength.AsRatio, 1000);

// TangentAtFrom, distanceAlongCurve = -1.2
poly_normal = GeometryEngine.Instance.QueryNormal(polyline, SegmentExtensionType.ExtendTangentAtFrom, -1.2, AsRatioOrLength.AsRatio, 1000);
seg_normal = GeometryEngine.Instance.QueryNormal(arc, SegmentExtensionType.ExtendTangentAtFrom, -1.2, AsRatioOrLength.AsRatio, 1000);

// TangentAtTo (ignored because distanceAlongCurve < 0), distanceAlongCurve = -1.2
poly_normal = GeometryEngine.Instance.QueryNormal(polyline, SegmentExtensionType.ExtendTangentAtTo, -1.2, AsRatioOrLength.AsRatio, 1000);
seg_normal = GeometryEngine.Instance.QueryNormal(arc, SegmentExtensionType.ExtendTangentAtTo, -1.2, AsRatioOrLength.AsRatio, 1000);

// TangentAtTo, distanceAlongCurve = 1.2
poly_normal = GeometryEngine.Instance.QueryNormal(polyline, SegmentExtensionType.ExtendTangentAtTo, 1.2, AsRatioOrLength.AsRatio, 1000);
seg_normal = GeometryEngine.Instance.QueryNormal(arc, SegmentExtensionType.ExtendTangentAtTo, 1.2, AsRatioOrLength.AsRatio, 1000);

// TangentAtFrom (ignored because distanceAlongCurve > 0), distanceAlongCurve = 1.2
poly_normal = GeometryEngine.Instance.QueryNormal(polyline, SegmentExtensionType.ExtendTangentAtFrom, 1.2, AsRatioOrLength.AsRatio, 1000);
seg_normal = GeometryEngine.Instance.QueryNormal(arc, SegmentExtensionType.ExtendTangentAtFrom, 1.2, AsRatioOrLength.AsRatio, 1000);

// EmbeddedAtTo, distanceAlongCurve = 1.2
poly_normal = GeometryEngine.Instance.QueryNormal(polyline, SegmentExtensionType.ExtendEmbeddedAtTo, 1.2, AsRatioOrLength.AsRatio, 1000);
seg_normal = GeometryEngine.Instance.QueryNormal(arc, SegmentExtensionType.ExtendEmbeddedAtTo, 1.2, AsRatioOrLength.AsRatio, 1000);

// EmbeddedAtFrom, distanceAlongCurve = -0.2
poly_normal = GeometryEngine.Instance.QueryNormal(polyline, SegmentExtensionType.ExtendEmbeddedAtFrom, -0.2, AsRatioOrLength.AsRatio, 1000);
seg_normal = GeometryEngine.Instance.QueryNormal(arc, SegmentExtensionType.ExtendEmbeddedAtFrom, -0.2, AsRatioOrLength.AsRatio, 1000);
    Requirements

    Target Platforms: Windows 11, Windows 10

    ArcGIS Pro version: 3 or higher.
    See Also

    Reference

    IGeometryEngine Interface
    IGeometryEngine Members
    Overload List

     

     

    ©2024 Esri Inc., All Rights Reserved. Generated on Saturday, October 26, 2024

    Send feedback