Changes between Version 9 and Version 10 of UsersWikiplpgsqlfunctionsDistance

Timestamp:

10/12/09 18:06:38 (15 years ago)

Author:

robe

Comment:

--

UsersWikiplpgsqlfunctionsDistance

@@ -1 +1 @@
 == Distance related helper functions ==
 [wiki:UsersWikiplpgsqlfunctions Back To PL/PGSQL/SQL Functions]
+
+ * '''Find UTM (WGS84)  SRID for a point (in any SRID)'''
+{{{
+#!sql
+ -- Function: utmzone(geometry)
+ -- DROP FUNCTION utmzone(geometry);
+
+ CREATE OR REPLACE FUNCTION utmzone(geometry)
+   RETURNS integer AS
+ $BODY$
+ DECLARE
+     geomgeog geometry;
+     zone int;
+     pref int;
+
+ BEGIN
+     geomgeog:= ST_Transform($1,4326);
+
+     IF (ST_Y(geomgeog))>0 THEN
+        pref:=32600;
+     ELSE
+        pref:=32700;
+     END IF;
+
+     zone:=floor((ST_X(geomgeog)+180)/6)+1;
+
+     RETURN zone+pref;
+ END;
+ $BODY$ LANGUAGE 'plpgsql' IMMUTABLE
+   COST 100;
+}}}
+
  * '''An ST_Dwithin like function that uses indexes for degree point data'''
 [http://www.postgis.org/pipermail/postgis-users/2009-June/023711.html] (use for pre PostGIS 1.5.)