[MetaCRS] Oracle WKT

[Mateusz Loskot]

Norm Olsen wrote:
> Hello Frank . . .
> 
> Yes, Oracle 10 is significantly different from Oracle 9.  Never seen
> an Oracle 8, I don't think.  Could you send me some samples?

Norm,

Sorry, have no access to Oracle 8.

> Most all of these issues have been addressed in CS-MAP.  Off the top
> of my head, the issues are:
> 
> 1> The names of the definitions are all different, and most now
> include an EPSG reference.  This can be helpful, but cannot be relied
> upon.

I've also noticed it.

> 2> The PROJECTION element now rarely contains the name of a
> projection, but has a reference to an EPSG Coordinate System
> Operation definition.  This is not the EPSG Operation _Method_ code,
> it is an EPSG Coordinate _Operation_ code.  A table which mapped the
> EPSG Operation Code to a projection was built to CS-MAP to handle
> this.  Of course, this is a maintenance nightmare.

Yes, after some research, I also found that this is one
of the most frequent issue.
For example, EPSG 2000 has PROJECTION name set to
"British West Indies Grid (EPSG OP 19942)"
but if I've found it correctly, it should read
"Transverse_Mercator"

etc.

My aim is to build a mapping table for this too.

> 3> In some cases, there are no PARAMETER elements for the coordinate
> system definition.  Presumably, having the EPSG Coordinate Operation
> Code you can get the parameter values from the EPSG database.
> Perhaps for Oracle this is a piece of cake; not so for us mere
> mortals.
> 
> 4> Oracle 10 will now often include datum transformation parameters,
> but without the benefit of the TOWGS84 element.  Of course, this
> presents all the problems associated with the TOWGS84 element.  Code
> that parses the DATUM element will need to be able to handle these
> extra seven parameter values appropriately.  (I think there are
> always seven, my memory could be wrong.)
> 
> 5> Many numerical values are given to 20 or so decimal places; could
> cause problems with some parsers.


Norm, this information is of great help for us. Thanks!

> Handling Oracle 10 was your typical WKT pain in the posterior
> problem.  Distinguishing between 9 and 10 is also tricky, which we
> needed to do.  My condolences to whomever has to do this.  I am
> available for consultation and, perhaps more importantly, consolation
> and commiseration.

Thank you very much. I'll be surely back here if I have questions.

Greetings
-- 
Mateusz Loskot, http://mateusz.loskot.net
Charter Member of OSGeo, http://osgeo.org