Changes between Version 84 and Version 85 of WKTRaster/SpecificationWorking01

Timestamp:

Dec 18, 2009, 2:06:03 PM (14 years ago)

Author:

pracine

Comment:

—

WKTRaster/SpecificationWorking01

@@ -273 +273 @@
  This function should be used with precaution on raster with float pixel type as it could return one "geomval" (or polygon) per pixel. This kind of raster should be reclassified (using the planned ST_Reclassify(raster,...) function) before using ST_AsPolygon().
 
+ ST_AsWKTRaster() should not be used directly. Use ST_AsPolygon() instead.
+
  '''Implementation details'''
  
  This function construct the WKT strings representing the geometries grouping pixels of a raster having the same value. It does not directly construct geometries and therefore prevent WKT Raster from having to link with liblwgeom.a (see "Why avoid to link with PostGIS?" below) It should also return the value associated with this WKT polygon.
 
- It should be implemented as a C function passing the raster to GDAL and converting each polygon produced by the [http://www.gdal.org/gdal__alg_8h.html GDALPolygonize function] to a WKT string accompagned by its corresponding value in a wktgeomval type. See http://www.postgresql.org/docs/8.4/interactive/xfunc-c.html#AEN44970 on how to return rows and sets.
+ It should be implemented as a C function passing the raster to GDAL and converting each polygon produced by the [http://www.gdal.org/gdal__alg_8h.html GDALPolygonize function] to a WKT string accompagned by its corresponding value in a wktgeomval type. See http://www.postgresql.org/docs/8.4/interactive/xfunc-c.html#AEN44970 on how to return rows and sets in a C function.