[postgis-devel] [WKT Raster] For clearer and friendly georeferencing

Pierre Racine Pierre.Racine at sbf.ulaval.ca
Mon Jun 1 12:54:00 PDT 2009


In the WKT Raster specifications RT_GetGeoReference(raster) returns a
World File and according to the World File spec RT_UpperLeftX(raster)
and RT_UpperLeftY(raster) return the X and Y coordinate of the CENTER of
the top left pixel.


-World File is (or seams to be) an ESRI specific spec
-GDAL georeference scheme favor the CORNER of the top left pixel
-We are becoming more and more good friends with GDAL

To better stick to GDAL and to make everything clearer, I will change
the specs this way:

-RT_UpperLeftX() and RT_UpperLeftY() will now return the coordinate of
the top left CORNER of the top left pixel. This is also what we are
going to store as ipX & ipY in the future.
-RT_GeoReference(raster) will be renamed RT_GdalGeoTransform(raster)
-There will ge a new RT_ESRIWorldFile() function doing basically the
same as RT_GdalGeoTransform() but according to the world file specs

This will, by the way, fix our shifted RT_Envelope() (ticket 150) and
gdal2wktraster.py will stay unchanged.

Don't worry too much if this break your application (is there any?)
since I will anyway soon (today?) replace all the "RT_" prefixes with
"ST_" (ticket 151)...


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