Reduce (geometry Data Type)
Returns an approximation of the given geometry instance produced by running the Douglas-Peucker algorithm on the instance with the given tolerance.
For collection types, this algorithm operates independently on each geometry contained in the instance.
This algorithm does not modify Point instances.
On LineString instances, the Douglas-Peucker algorithm retains the original start and end points of the instance, and iteratively adds back the point from the original instance that most deviates from the result until no point deviates more than the given tolerance.
On Polygon instances, the Douglas-Peucker algorithm is applied independently to each ring. The method will produce a FormatException if the returned Polygon instance is not valid; for example, an invalid MultiPolygon instance is created if Reduce() is applied to simplify each ring in the instance and the resulting rings overlap.
The following example creates a LineString instance and uses Reduce() to simplify the instance.
DECLARE @g geometry; SET @g = geometry::STGeomFromText('LINESTRING(0 0, 0 1, 1 0, 2 1, 3 0, 4 1)', 0); SELECT @g.Reduce(.75).ToString();