Thanks for clearly stating that Adrian. Erich I am going to take a wild guess that when you have two epsg authorities on the classpath it is up to luck which one you get - since expected result lines up with epsg-wkt I am going to guess that is the one the GeoTools 2.4.x code based "picked out" for you.
My understanding is for GeoTools 2.5.x martin wisely lowered the priority of epsg-wkt (so it is no longer a "tie" with epsg-hsql) and thus you are now looking at results from epsg-hsql for the first time. I think if you return to your 2.4.x program and only include the epsg-hsql jar you should see similar results? And all things being equal my money is on the epsg-hsql result being correct. One of the "improvements" the epsg-hsql module offers is getting the axis order correct. Often when people make the transition they will find that their data is wrong - and they either have to switch the axis order to match the database (or specifically ask epsg-hsql to produce the wrong axis order) - see - http://docs.codehaus.org/display/GEOTDOC/07+Referencing for more info. I would recommend taking the time to explore the use of epsg-hsql - and if you want to compare against something (other than math in your head) download proj and run the same coordinate through it. Jody Adrian Custer wrote: > Let's distinguish *wrong* results which are non-sensical from *bad* > results which are in the ballpark but non-usable because far off. > > > The former are generally due to configuration issues such as axes being > flipped in factories or similar problems. It sounds like this is the > kind of issue you are having with hsql. You could confirm that by seeing > if some of the more common, simpler transforms do not work either. > > The latter are either limitations of the epsg source (I think, for > example, WKT does not include bursa-wolf parameters so, if they are > needed, you can get imprecisions with your transformations based on the > wkt database), or limitations of the library, ie. we can't yet do > certain kinds of transformations. > > Of course, these errors can be due to remaining bugs in the code but > that's an increasingly infrequent issue. > > So, if you have remaining errors and want to chase them down, make sure > you understand (1) what you want to do including the math which should > be happening (2) how to setup the referencing library (see the wiki on > the website) including the factory system and (3) what the results that > you see look like, e.g. what happens to four points which start as a box > or when you flip the input coordinates. > > > >> while wkt results look plausible. For >> this I will use GT 2.5. >> Nearby: Is there any disadvantage using wkt instead of hqsql? >> > > yes, it's on the way out; it includes fewer entries; it is based on an > older database, and, I think, does not include the more complex > parameters required for precise computations of certain operations. > > But look on the web site, there are probably details there. > http://docs.codehaus.org/display/GEOTDOC/09+Referencing+Authority > +Factories > http://docs.codehaus.org/display/GEOTDOC/EPSG+WKT+Plugin > http://docs.codehaus.org/display/GEOTDOC/EPSG+HSQL+Plugin > > well, we should do a better job of describing those. I'll ask someone > who understands the differences between the four jars better than I do > to improve that text. > --adrian > > > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Geotools-gt2-users mailing list > Geotools-gt2-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users > ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Geotools-gt2-users mailing list Geotools-gt2-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
