Martin Desruisseaux wrote: > For a given target datum, we pickup the first set of parameters returned by a > SQL statement that contains the following clause: > > ORDER BY ABS(DEPRECATED), COORD_OP_ACCURACY, COORD_OP_CODE DESC > > So deprecated parameters are last. If there is more than one non-deprecated > set > of parameters, the most accurate one is selected. If they all have the same > accuracy, we choose the one with the highest primary key value, assuming that > it > is the most recently added. I admit that this last rule is not a very reliable > one, but in the particular case of EPSG:4289, it seems to work.
Martin, Ah, interesting. I am personally quite afraid of picking one of several transformations even with such rules. But I must confess that uses of PROJ, OGR and other software derived from the libgeotiff translation of the EPSG database are constantly faced with no easily available transformation which is likely worse than just picking one. I'll consider applying a similar rule in my work. I do think it is important for you to make it clear to users that you have picked one of several possible transformations for datums, and that it may not be the best one for their region of operation. Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, [EMAIL PROTECTED] light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | President OSGeo, http://osgeo.org ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Geotools-gt2-users mailing list Geotools-gt2-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
