[gdal-dev] Ogr2ogr -dim and Oracle

[Ivan Lucena]

Hi,


a) If you look at this code here [1] from the raster driver, there are two function, FIND_GEOG_CRS and FIND_PROJ_CRS, that uses the WKT string to find matches with inside SRS.


That runs independently from Authority code and returns a list of possible matches SRIDs. The driver takes the first one automatically.


Looking back on that code, there is a lot of property-name strings that need to be adjusted, adding or removing some "_" or uppercase here and there.


b) I believe that EPSG codes are supported since version 11.


c) The -lco SRID is still useful. The way the OCI driver code works now "-a_srs EPSG:4326" will be translated to SRID 8078 (or something like that).


That is how the driver was originally developed, when EPSG was not supported yet. By using -lco SRID 4326 users can overwrite that.



I am kind of thinking about merging the two Oracle driver into one "raster/vector" driver. Any advice on that will be gladly accepted.



Regards,

Ivan


[1] - https://trac.osgeo.org/gdal/browser/trunk/gdal/frmts/georaster/georaster_dataset.cpp#L1673


________________________________
From: Rahkonen Jukka (MML) <jukka.rahkonen at maanmittauslaitos.fi>
Sent: Thursday, November 17, 2016 9:18:43 AM
To: Even Rouault; Ivan Lucena
Cc: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] Ogr2ogr -dim and Oracle

Hi,

Probably SDO_COORD_REF_SYS is what to use nowadays even I guess that it points to MDSYS tables. Looks like something has changed with Oracle 10.2 and I believe that it is very hard to use so old Oracle version without paying much extra.
https://docs.oracle.com/database/121/SPATL/GUID-7DEF5C91-777C-4023-AE2E-E2E29F5213D2.htm#SPATL652

-Jukka Rahkonen-


Even Rouault wrote:

Le jeudi 17 novembre 2016 14:19:10, Ivan Lucena a écrit :
> Hi Even,
>
>> Did you try your change?

>Yes

>>
> There has been a lot of changes in both sides over the years that are
> not reflected on the OCI driver code.
>
> That hard coded SRID conversion should be deleted since EPSG is fully
> supported now.

Do you know which since which version of OCI this "now" apply ?

With 11.2.0, I see things like :

OGRFeature(select * from MDSYS.CS_SRS):6
  CS_NAME (String) = NAD83(CSRS98) / UTM zone 17N
  SRID (Integer64) = 2150
  AUTH_SRID (Integer64) = 2150
  AUTH_NAME (String) = Geomatics Canada.
  WKTEXT (String) = PROJCS["NAD83(CSRS98) / UTM zone 17N", GEOGCS [ "NAD83(CSRS98)", DATUM ["NAD83 Canadian Spatial Reference System (EPSG ID 6140)", SPHEROID ["GRS 1980 (EPSG ID 7019)", 6378137.0, 298.257222101]], PRIMEM [ "Greenwich", 0.000000 ], UNIT ["degree minute second hemisphere", 0.0174532925199433]], PROJECTION ["Transverse Mercator"], PARAMETER ["Latitude_Of_Origin", 0.0], PARAMETER ["Central_Meridian", -81.0], PARAMETER ["Scale_Factor", 0.9996], PARAMETER ["False_Easting", 500000.0], PARAMETER ["False_Northing", 0.0], UNIT ["Meter", 1.0]]
  WKTEXT3D (String) = PROJCS[
  "NAD83(CSRS98) / UTM zone 17N",
  GEOGCS["NAD83(CSRS98)",
    DATUM["NAD83 Canadian Spatial Reference System",
      SPHEROID[
        "GRS 1980",
        6378137.0,
        298.257222101,
        AUTHORITY["EPSG", "7019"]],
      TOWGS84[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
      AUTHORITY["EPSG", "6140"]],
    PRIMEM["Greenwich", 0.000000, AUTHORITY["EPSG","8901"]],
    UNIT["degree minute second hemisphere", 0.0174532925199433, AUTHORITY["EPSG", "9108"]],
    AXIS["Lat", NORTH],
    AXIS["Long", EAST],
    AUTHORITY["EPSG", "4140"]],
  PROJECTION ["Transverse Mercator"],
  PARAMETER ["Latitude_Of_Origin", 0.0],
  PARAMETER ["Central_Meridian", -81.0],
  PARAMETER ["Scale_Factor", 0.9996],
  PARAMETER ["False_Easting", 500000.0],
  PARAMETER ["False_Northing", 0.0],
  UNIT["metre", 1.0, AUTHORITY["EPSG", "9001"]],
  AXIS["E", EAST],
  AXIS["N", NORTH],
  AUTHORITY["EPSG", "2150"]]

What surprises me is the AUTH_NAME which is not EPSG (for other codes it is null). So it is not entirely clear how you would find the SRID if you can't search by AUTH_NAME = 'EPSG' AND AUTH_SRID = epsg_code. Skimming through the list, it seems that SRID = AUTH_SRID for EPSG codes however.

>
> He georaster driver uses some PLSQL functions to try to match WKT to
> possible SRIDs. That could be added to the OCI. I think.

OK. Good to know

Even

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