Changes between Version 79 and Version 80 of WKTRaster/SpecificationWorking01

Timestamp:

Dec 18, 2009, 12:48:03 PM (14 years ago)

Author:

pracine

Comment:

—

WKTRaster/SpecificationWorking01

@@ -239 +239 @@
 '''ST_AsPolygon(raster) -> polygon geometry set''' - Returns a set of geometry, one for each group of pixel having the same value.
 
- The shape of each polygon should exactly follow pixels edges.
+ This is a set-returning function (SRF). The shape of each polygon should exactly follow pixels edges.
 
  A ST_AsPolygon(raster, 'GROUP') variant should regroup every resulting polygon having the same value into complex (or multipart) polygons.
@@ -249 +249 @@
  This function is at the base of the first version of ST_Intersection which compute the intersection between a raster and a geometry.
 
- 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: 
-
- FOR poly IN SELECT ST_GeomFromText(ST_AsWKTPolygon(rast)) FROM table LOOP
+ 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;