Changes between Version 59 and Version 60 of WKTRaster/SpecificationWorking01

Timestamp:

Dec 16, 2009, 10:52:21 AM (14 years ago)

Author:

pracine

Comment:

—

WKTRaster/SpecificationWorking01

@@ -192 +192 @@
 '''ST_Box2D(raster) -> BOX2D'''  Returns a BOX2D representing the maximum extents of the geometry.
 
- This function replaces ST_Raster_to_box2d() and should be used for the "raster AS box2d" cast. It should also be used when creating indexes in gdal2wktraster.py.
+ This function replaces ST_Raster_to_box2d() and should be used for the "raster AS box2d" cast. It should also be used instead of ST_raster_envelope when creating indexes in gdal2wktraster.py (to be tested).
 
 '''ST_Envelope(raster) -> polygon geometry''' Returns the minimum bounding box for the supplied raster, as a geometry. If the raser is rotated, the envelope is a non-rotated box enclosing the rotated raster.
@@ -200 +200 @@
 '''ST_ConvexHull(raster) -> polygon geometry''' Returns the minimum convex geometry that encloses every significant pixel from the raster. 
 
- By default the resulting polygon TAKES the NODATA values into account. The resulting polygon enclose only pixels actually having a value (different than the NODATA value). The ST_ConvexHull(raster, 'WITHNODATA') variant DO NOT TAKE the NODATA value into account. It generally returns a square or rectangle polygon that can be rotated or not depending on the rotation of the raster. If the raster is not rotated ST_ConvexHull(geometry, 'WITHNODATA') is (almost) equivalent to ST_Envelope(raster).
-
-'''ST_Shape(raster) -> polygon geometry'''- Returns .
-
-'''ST_AsPolygon(raster) -> polygon geometry set''' Returns a 
+ By default the resulting polygon TAKES the NODATA values into account. The resulting polygon enclose only pixels having a significant value (different than the NODATA value). The ST_ConvexHull(raster, 'WITHNODATA') variant DO NOT TAKE the NODATA value into account. It generally returns a square or rectangle polygon that can be rotated or not depending on the rotation of the raster. If the raster is not rotated ST_ConvexHull(geometry, 'WITHNODATA') is (almost) equivalent to ST_Envelope(raster).
+
+'''ST_Shape(raster) -> polygon geometry'''- Returns a geometry encomparsing every pixel having a significant value (different than the NODATA value). This geometry might contain holes if some internal areas of the raster contain pixels with NODATA values.
+
+'''ST_AsPolygon(raster) -> polygon geometry set''' Returns a geometry for each 
 
 ST_GetBBox(raster) (not yet implemented but planned) is replaced with ST_Envelope() since there is no equivalent function in PostGIS.