Update to the SQL Server Spatial Tools project on CodePlex

  • Article

As Isaac noted in his most recent post, the SQL Server Spatial Tools project on CodePlex has been updated with several new geography functions. This post provides additional detail on the new features:

  • IsValidGeographyFromGeometry
  • IsValidGeographyFromText
  • MakeValidGeographyFromGeometry
  • MakeValidGeographyFromText
  • ConvexHullGeography
  • ConvexHullFromText

Here are descriptions for each:

bool IsValidGeographyFromGeometry(SqlGeometry geometry)
Check if an input geometry can represent a valid geography without throwing an exception. This function requires that the geometry be in longitude/latitude coordinates and that those coordinates are in correct order in the geometry instance (i.e. latitude/longitude not longitude/latitude). This function will return false (0) if the input geometry is not in the correct latitude/longitude format, including a valid geography SRID.

bool IsValidGeographyFromText(string inputWKT, int srid)
Check if an input WKT can represent a valid geography. This function requires that the WTK coordinate values are longitude/latitude values, in that order and that a valid geography SRID value is supplied. This function will not throw an exception even in edge conditions (i.e. longitude/latitude coordinates are reversed to latitude/longitude).

SqlGeography MakeValidGeographyFromGeometry(SqlGeometry geometry)
Convert an input geometry instance to a valid geography instance. This function requires that the WKT coordinate values are longitude/latitude values, in that order and that a valid geography SRID value is supplied.

SqlGeography MakeValidGeographyFromText(string inputWKT, int srid)
Convert an input WKT to a valid geography instance. This function requires that the WKT coordinate values are longitude/latitude values, in that order and that a valid geography SRID value is supplied.

SqlGeography ConvexHullGeography(SqlGeography geography)
Computes ConvexHull of input geography and returns a polygon (unless all input points are collinear).

SqlGeography ConvexHullGeographyFromText(string inputWKT, int srid)
Computes ConvexHull of input WKT and returns a polygon (unless all input points are collinear). This function does not require its input to be a valid geography. This function does require that the WKT coordinate values are longitude/latitude values, in that order and that a valid geography SRID value is supplied.

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