CurveToLineWithTolerance (geometry Data Type)

THIS TOPIC APPLIES TO:yesSQL Server (starting with 2012)yesAzure SQL DatabasenoAzure SQL Data Warehouse noParallel Data Warehouse

Returns a polygonal approximation of a geometry instance that contains circular arc segments.

Syntax


.CurveToLineWithTolerance ( tolerance, relative )  

Arguments

tolerance
Is a double expression that defines the maximum error between the original circular arc segment and its linear approximation.

relative
Is a bool expression that indicates whether to use a relative maximum for the deviation. When relative is set to false (0), then an absolute maximum is set for the deviation that a linear approximate can have. When relative is set to true (1) then the tolerance is calculated as a product of the tolerance parameter and the diameter of the bounding box for the spatial object.

Return Types

SQL Server return type: geometry

CLR return type: SqlGeometry

Exceptions

Setting tolerance <= 0 throws an ArgumentOutOfRange exception.

Remarks

This method can specify an error tolerance amount for the resultant LineString.

The following table shows the instance type returned by CurveToLineWithTolerance()for various types.

Invoking Instance Type Spatial Type Returned
Empty geometry instance Empty GeometryCollection instance
Point and MultiPoint Point instance
MultiPoint Point or MultiPoint instance
CircularString, CompoundCurve, or LineString LineString instance
MultiLineString LineString or MultiLineString instance
CurvePolygon and Polygon Polygon instance
MultiPolygon Polygon or MultiPolygon instance
GeometryCollection with a single instance that does not contain a circular arc segment The instance that is contained in the GeometryCollection determines the type of instance returned.
GeometryCollection with a single one-dimensional circular arc segment instance (CircularString, CompoundCurve) LineString instance
GeometryCollection with a single two-dimensional circular arc segment instance (CurvePolygon) Polygon instance
GeometryCollection with multiple one dimensional instances MultiLineString instance
GeometryCollection with multiple two dimensional instances MultiPolygon instance
GeometryCollection with multiple instances of different dimensions GeometryCollection instance

Examples

A. Using different tolerance values on a CircularString instance

The following example shows how setting the tolerance affects the LineStringinstance returned from a CircularString instance:

DECLARE @g geometry;

SET @g = geometry::Parse('CIRCULARSTRING(0 0, 1 2.1082, 3 6.3246, 0 7, -3 6.3246, -1 2.1082, 0 0)');

SELECT @g.CurveToLineWithTolerance(0.1,0).STNumPoints(), @g.CurveToLineWithTolerance(0.01, 0).STNumPoints();

B. Using the method on a MultiLineString instance containing one LineString

The following example shows what is returned from a MultiLineString instance that only contains one LineString instance:

DECLARE @g geometry;

SET @g = geometry::Parse('MULTILINESTRING((1 3, 4 8, 6 9))');

SELECT @g.CurveToLineWithTolerance(0.1,0).ToString();

C. Using the method on a MultiLineString instance containing multiple LineStrings

The following example shows what is returned from a MultiLineString instance that contains more than one LineString instance:

DECLARE @g geometry;

SET @g = geometry::Parse('MULTILINESTRING((1 3, 4 8, 6 9),(4 4, 9 18))');

SELECT @g.CurveToLineWithTolerance(0.1,0).ToString();

D. Setting relative to true for an invoking CurvePolygon instance

The following example uses a CurvePolygon instance to call CurveToLineWithTolerance() with relative set to true:

DECLARE @g geometry = 'CURVEPOLYGON(COMPOUNDCURVE(CIRCULARSTRING(0 4, 4 0, 8 4), (8 4, 0 4)))';

SELECT @g.CurveToLineWithTolerance(.5,1).ToString();

E. Using the method on a GeometryCollection instance

The following example calls CurveToLineWithTolerance() on a GeometryCollection that contains a two-dimensional CurvePolygon instance and a one-dimensional CircularString instance. CurveToLineWithTolerance() converts both circular arc segment types to line segment types and returns them in a GeometryCollection type.

DECLARE @g geometry;

SET @g = geometry::Parse('GEOMETRYCOLLECTION(CURVEPOLYGON( COMPOUNDCURVE(CIRCULARSTRING(0 2, 2 0, 4 2), (4 2, 0 2))), CIRCULARSTRING(4 4, 8 6, 9 5))');

SELECT @g.CurveToLineWithTolerance(0.1,0).STNumPoints(), @g.CurveToLineWithTolerance(0.1, 0).ToString();

See Also

CurveToLineWithTolerance (geography Data Type)
STCurveToLine (geometry Data Type)