Oracle WKTEXT Translation

[warmerdam]

The following WKTEXT value from Oracle is not handled properly in OGR bccause the PROJECTION[] name has a space in it. We need morph to/from oracle methods in ogrocidatasource.cpp to remap projection names and other identified oddities of Oracle format.

PROJCS["GK Zone 4 (DHDN)", GEOGCS [ "", DATUM ["", SPHEROID ["Bessel 1841",
6377397.155, 299.1528128], 582.000000, 105.000000, 414.000000, -1.040000,
-0.350000, 3.080000, 8.300000 ], PRIMEM [ "Greenwich", 0.000000 ], UNIT
["Decimal Degree", 0.01745329251994330]], PROJECTION ["Transverse Mercator"],
PARAMETER ["Scale_Factor", 1.000000], PARAMETER ["Central_Meridian", 12.000000],
PARAMETER ["False_Easting", 4500000.000000], UNIT ["Meter", 1.000000000000]]

[warmerdam]

I see the DATUM also has a bunch of unlabelled numeric parameters
were are presumably TOWGS84 values.  It would be nice to handle them properly
too. 

[warmerdam]

More fun mateusz...

[Mateusz Łoskot]

File with the Oracle WKT making problems

[Mateusz Łoskot]

Python script reading the Oracle WKT using importFromWkt() method

[Mateusz Łoskot]

Frank,

This issue is not clear to me and I'd need more details.

What does it mean that OGR does not handle the WKT properly? Does OGR crash or can't read this WKT?

I attached test.py script with very simple test of how the reported WKT is parsed and here is what I get:

mloskot:~/dev/gdal/bugs/1183$ ./test.py
Type      : projected
PROJCS    : GK Zone 4 (DHDN)
GEOGCS    : 
DATUM     : 
SPHEROID  : Bessel 1841
PRIMEM    : Greenwich
PROJECTION: Transverse Mercator

The space in PROJECTION name seems to be parsed correctly, isn't it?

[warmerdam]

Matuesz,

OGR expects "Transverse_Mercator" as the PROJECTION[] name for Transverse Mercator projections. The above will note validate, nor be successfully interchanged with anything else.

I think we need to review the contents of the WKT for Oracle for a few different versions. I've heard things improved to be more OGC compatible in 10g, though I don't know that for sure. Ultimately it seems likely we will need something like the morphToESRI(), morphFromESRI() methods used for the ESRI variant of WKT.

[warmerdam]

BTW, I suspect this is too complex an issue to fix for in the 1.4 branch, so I'm setting this to 1.5.0 milestone. If it turns out there are some simple things we can do to improve function in 1.4 branch, then that's great too.

[warmerdam]

OCI issues deferred to 1.5.1.

[Mateusz Łoskot]

Frank,

I'd like to take this ticket up. Could you give some update for your comments, about how to solve properly? Should I just look at other morphers and catch WKT differences specific for Oracle, and implement morphTo/FromOracle ?

[warmerdam]

Mateusz,

Yes, please proceed with a morphToOracle() / morphFromOracle().

I would appreciate it if you could write up some description of the issues with Oracle WKT - perhaps as a trac wiki topic for now.

It might make sense to just do this morph work in trunk rather than trying to address 1.5 branch.

[Mateusz Łoskot]

On the MetaCRS list, we (Frank) ​asked for comments and experiences on dealing with Oracle WKT CS definitions. Norm Olsen gave us ​very helpful notes.

Source code of ​CS-Map project is going to be public soon. As Norm confirmed, it already includes mapping tables of Oracle WKT specifics to OGC format, etc.

So we have decided to defer work on this ticket for a few weeks and wait for CS-Map sources.

[hobu]

CS-Map is now public, but no one has had time to work on this effort. Is it likely that it would be part of a larger effort to include CS-Map as an alternative coordinate system description engine?

Anyway, kicking forward to 1.7, but I expect it will be after that...

[warmerdam]

I don't anticipate action on this soon.

[Jukka Rahkonen]

Oracle has a support for standard EPSG-codes since long beginning from version 10g. I believe and hope that there is no need for any WKT based morphToOracle any more and we can close this ticket as won't fix. I will wait a week or two for feedback.

[Jukka Rahkonen]

Seven weeks passed without feedback, closing.