Re: [udig-devel] Re: CRS - "Bursa wolf parameters required."

[Paul Ramsey <pramsey@xxxxxxxxxxxxxxx>]

Direct GeoTools access to the EPSG database is a "great idea" that noone 
has actually implemented. It was once implemented, but is not working 
now. The only "epsg" data we have now is a WKT properties files I hacked 
up many moons ago, precisely because the EPSG database was not working / 
ready.

Yes, if we had an ESPG database, the DatumAliases could also reference 
an EPSG datum ID, which in turn would allow us to look up transforms 
between those actual datums, which would be very nice. But we would 
still need to do the DatumAliases trick.

P

Matthias Basler wrote:

> Paul Ramsey wrote
>
> > One thing we can do (prepare for the pain) is to add yet more
> > information to our DatumAliases -- for each DatumAlias, add the BW
> > transform parameters to WGS84. That way, if we come across a particular
> > datum name, but lack TOWGS[] information, we can fill it in ourselves.
> > Otherwise it'll be death and destruction quite frequently: most apps
> > generating WKT do *not* generate the TOWGS[] portions of the WKT.
>
>
> Maybe this is a very stupid question: Doesn't support GeoTools the use of the
> EPSG database for getting the transformation parameters? AFAIK most CRS are
> exactly defined in the EPSG database (including Bursa wolf parameters and other
> means of reprojection), so all missing information can be retrieved from it,
> cannot it?
>
> Since I'm interested in the reprojection functionality myself, maybe someone can
> shortly outline to me how this currently handled in uDig/GeoTools2.1.
>
> Matthias Basler
> c9bama@xxxxxxxxxxx
>
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