Changes between Version 80 and Version 81 of WKTRaster/SpecificationWorking01

Timestamp:

Dec 18, 2009, 1:21:16 PM (14 years ago)

Author:

pracine

Comment:

—

WKTRaster/SpecificationWorking01

@@ -251 +251 @@
  To avoid linking directly with PostGIS (see "Why avoid to link with PostGIS?" below) It should be implemented as a PL/pgSQL wrapper around ST_AsWKTPolygon() looking something like this:
 
- CREATE TYPE raster_geom AS (value integer[], geom geometry);
- 
-
- FOR poly IN SELECT ST_GeomFromText(r.geom),  FROM ST_AsWKTPolygon(rast) AS r LOOP
-  RETURN NEXT poly;
- END LOOP;
+ CREATE TYPE geomval AS (geom geometry, val float8);
+ CREATE TYPE wktgeomval AS (wktgeom text, val float8);
+
+ CREATE OR REPLACE FUNCTION ST_AsPolygon(rast) RETURNS SETOF geomval AS
+ $BODY$
+ DECLARE
+     pl geomval%rowtype;
+ BEGIN
+     FOR pl IN SELECT ST_GeomFromText(wktgeomval.wktgeom), wktgeomval.val FROM ST_Dump(ST_GeomFromText(txtgeom)) AS wktgeomval 
+     LOOP
+        RETURN NEXT pl;
+     END LOOP;
+     RETURN;
+ END
+ $BODY$
+ LANGUAGE 'plpgsql';
+
+ So it can then be used like this:
+
+ SELECT (ST_AsPolygon(rast)).val, (ST_AsPolygon(rast)).geom FROM sometable
 
 '''ST_AsWKTPolygon(raster) -> text set''' - Returns a set of text representation of geometry, one for each group of pixel having the same value.