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    STDensify: Densify (m)LineString or (m)Polygon geometry objects
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    STRound: Function to round ordinates of a SQL Server Spatial geometry object
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    Tip #1: SQL Server 2008 "Katmai" - Setting SRIDs



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All Blog Articles, Data Models and Free Source Code by Simon Greener, The SpatialDB Advisor is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

STRound: Function to round ordinates of a SQL Server Spatial geometry object

Tuesday January 03 2012 at 06:08

Keywordsround ordinate coordinate tolerance geometry SQL Server Spatial STRound

The presented function allows a user to round the ordinates of a Sql Server Spatial geometry object to the user’s understood geometric precision.

The result of many geoprocessing operations in any spatial type can be geometries with ordinates (X, Y etc) that have far more decimal digits of precision than the initial geometry.

I present here a simple function STRound that takes a geometry object and some specifications of the precision of any X, Y, Z or M ordinates, applies those specifications to the geometry and returns the corrected geometry.

  1. USE [GISDB] -- Change this to your database
  2. GO
  3. -- Drop if exists
  4. --
  5. DROP FUNCTION [dbo].[STRound];
  6. -- Now create
  7. --
  8. CREATE FUNCTION [dbo].[STRound]
  9. (
  10.   @p_geometry geometry,
  11.   @p_round_xy INT = 3,
  12.   @p_round_zm INT = 2
  13. )
  14. RETURNS geometry
  15. AS
  16. BEGIN
  17.    -- Implementation;
  18. GO

Testing this we get.

  1. -- Point
  2. SELECT [dbo].[STRound](geometry::STPointFromText('POINT(0.345 0.282)',0),1,1).STAsText() AS RoundGeom;
  3. GO
  4. RoundGeom
  5. POINT (0.3 0.3)
  6. -- MultiPoint
  7. SELECT [dbo].[STRound](geometry::STGeomFromText('MULTIPOINT((100.12223 100.345456),(388.839 499.40400))',0),3,1).STAsText() AS RoundGeom;
  8. GO
  9. RoundGeom
  10. MULTIPOINT ((100.122 100.345), (388.839 499.404))
  11. -- Linestring
  12. SELECT [dbo].[STRound](geometry::STGeomFromText('LINESTRING(0.1 0.2,1.4 45.2)',0),2,1).STAsText() AS RoundGeom;
  13. GO
  14. RoundGeom
  15. LINESTRING (0.1 0.2, 1.4 45.2)
  16. -- LinestringZ
  17. SELECT [dbo].[STRound](geometry::STGeomFromText('LINESTRING(0.1 0.2 0.312,1.4 45.2 1.5738)',0),2,1).AsTextZM() AS RoundGeom;
  18. GO
  19. RoundGeom
  20. LINESTRING (0.1 0.2 0.3, 1.4 45.2 1.6)
  21. -- Polygon
  22. SELECT [dbo].[STRound](geometry::STGeomFromText('POLYGON((0 0,10 0,10 10,0 10,0 0))',0),2,1).STAsText() AS RoundGeom;
  23. GO
  24. RoundGeom
  25. POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))
  26. -- MultiPolygon
  27. SELECT [dbo].[STRound](
  28.          geometry::STGeomFromText('MULTIPOLYGON (((160 400, 200.00000000000088 400.00000000000045, 200.00000000000088 480.00000000000017, 160 480, 160 400)), ((100 200, 180.00000000000119 300.0000000000008, 100 300, 100 200)))',0),
  29.           2,1).STAsText() AS RoundGeom;
  30. GO
  31. RoundGeom
  32. MULTIPOLYGON (((160 400, 200 400, 200 480, 160 480, 160 400)), ((100 200, 180 300, 100 300, 100 200)))
I hope this is useful to someone.

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Comment [2]

Do you have the code for the STRound function?
I saw it here:


Gordon Luckett 7 May 2019, 03:55 #

Is there an implementation of this function…

Mark D Drake 7 May 2019, 15:54 #