MIGRATION_GUIDE.TXT

MIGRATION GUIDE FROM GDAL 3.6 to GDAL 3.7
-----------------------------------------

- Following RFC 87, PIXELTYPE=SIGNEDBYTE in IMAGE_STRUCTURE metadata domain is
  no longer reported by drivers that used to do it. The new GDT_Int8 data type
  is now reported.
  On writing, the PIXELTYPE=SIGNEDBYTE creation option is preserved in drivers
  that used to support it, but is deprecated and external code should rather use
  the GDT_Int8 data type.

- The VSILFILE* type is no longer aliased to FILE* in builds without the DEBUG
  define (that is production builds). External code that used FILE* with
  GDAL VSI*L API has to be changed to use VSILFILE*.
  This aliasing dates back to old times where both types were indifferently
  used in the code base. In the mean time, this was cleaned up. But there was a
  drawback of having VSILFILE* being either a dedicated type oor an alias of
  FILE* depending whether DEBUG is defined, especially with the C++ API, for
  people building their plugins with DEBUG and running them against a non-DEBUG
  GDAL build, or the reverse.

MIGRATION GUIDE FROM GDAL 3.5 to GDAL 3.6
-----------------------------------------

- Out-of-tree vector drivers:
  * GDALDataset::IBuildOverviews(): parameters panOverviewList and panBandList
    are now of type 'const int*' (previously 'int*')
    Added a CSLConstList papszOptions member.
  * GDALRasterBand::BuildOverviews(): parameter panOverviewList is now of
    type 'const int*' (previously 'int*')
    Added a CSLConstList papszOptions member.
  * Compatibility layers of GDAL 3.0 _GetProjectionRef(), _GetGCPProjectionRef(),
    _SetProjection(), _SetGCPs() have been removed

MIGRATION GUIDE FROM GDAL 3.4 to GDAL 3.5
-----------------------------------------

- GDAL drivers may now return raster bands with the new data types GDT_Int64 or
  GDT_UInt64.
- Make GDALProxyRasterBand::RefUnderlyingRasterBand() / UnrefUnderlyingRasterBand() const. May affect out-of-tree drivers

MIGRATION GUIDE FROM GDAL 3.3 to GDAL 3.4
-----------------------------------------

- Out-of-tree vector drivers:
    * OGRFeatureDefn protected member variables have been changed.
        - (nFieldCount, papoFieldDefn)        ==> std::vector<std::unique_ptr<OGRFieldDefn>> apoFieldDefn{};
        - (nGeomFieldCount, paoGeomFieldDefn) ==> std::vector<std::unique_ptr<OGRGeomFieldDefn>> apoGeomFieldDefn{};
    * OGRFeatureDefn::AddGeomFieldDefn( OGRGeomFieldDefn *, bCopy = FALSE ) is
      replaced by AddGeomFieldDefn( std::unique_ptr<OGRGeomFieldDefn>&& )
    * GDALDataset::FlushCache() and GDALRasterBand::FlushCache() now takes a bool bAtClosing argument.
      That argument is set to true when FlushCache() is called from the dataset/band destructor.
      This can be used as a hint, for example to avoid doing extra work if the dataset is marked
      for deletion at closing. Driver implementing that method should propagate the argument to the
      base implementation when calling it.

MIGRATION GUIDE FROM GDAL 3.2 to GDAL 3.3
-----------------------------------------

- Python bindings:
  * Python 2 is no longer supported per RFC 77. Python 3.6 or later required
  * "osgeo.utils" was replaced by "osgeo_utils" (more details: see RFC78)
  * The following undocumented, untested utility scripts are no longer installed as system scripts and were moved
    from "gdal/swig/python/gdal-utils" to: "gdal/swig/python/gdal-utils/samples":
    - epsg_tr.py
    - esri2wkt.py
    - gcps2vec.py
    - gcps2wld.py
    - gdal_auth.py
    - gdalchksum.py
    - gdalident.py
    - gdalimport.py
    - mkgraticule.py
    In order to import sample script X (i.e. `epsg_tr`) as a module, use: `from osgeo_utils.samples import X`.
    In order to run it as a script run: `python -m osgeo_utils.samples.X`.
  * packaging:
    - "gdal/swig/python/samples" moved to: "gdal/swig/python/gdal-utils/osgeo_utils/samples"
    - "gdal/swig/python/scripts" moved to: "gdal/swig/python/gdal-utils/scripts"
- gdaldem TRI: default algorithm has been changed to use Riley et al. 1999. Use -alg Wilson to select the algorithm used previously
- Disable by default raster drivers DODS, JPEG2000(Jasper), JPEGLS, MG4LIDAR, FUJIBAS, IDA, INGR, ZMAP and vector driver ARCGEN, ArcObjects, CLOUDANT, COUCHDB, DB2, DODS, FME, GEOMEDIA, GTM, INGRES, MONGODB, REC, WALK at runtime, unless the GDAL_ENABLE_DEPRECATED_DRIVER_{drivername} configuration option is set to YES. Those drivers are planned for complete removal in GDAL 3.5
- Perl bindings are deprecated. Removal planned for GDAL 3.5. Use Geo::GDAL::FFI instead
- Removal of BNA, AeronavFAA, HTF, OpenAir, SEGUKOOA, SEGY, SUA, XPlane, BPG, E00GRID, EPSILON, IGNFHeightASCIIGrid, NTV1 drivers. Moved to (unsupported) https://github.com/OSGeo/gdal-extra-drivers repository.

MIGRATION GUIDE FROM GDAL 3.1 to GDAL 3.2
-----------------------------------------

- Python bindings: old-style, deprecated for many years, import method of
  importing the gdal module through "import gdal" is no longer available.
  "from osgeo import gdal" must now be used. This holds true for the ogr, osr,
  gdalconst and gdalnumeric modules.


MIGRATION GUIDE FROM GDAL 3.0 to GDAL 3.1
-----------------------------------------

- OGR SQL: the 'LIKE' operator is now case sensitive by default. ILIKE (supported
  in previous versions) must be used for case insensitive comparison. The
  OGR_SQL_LIKE_AS_ILIKE configuration option can be set to YES to make LIKE behave
  in a case insensitive way as in previous versions.

MIGRATION GUIDE FROM GDAL 2.4 to GDAL 3.0
-----------------------------------------

- Unix Build: ./configure arguments --without-bsb, --without-grib,
  and --without-mrf have been renamed to --disable-driver-bsb,
  --disable-driver-grib and --disable-driver-mrf
 - Unix build: Arguments of --with-pg changed to yes/no only.
- Substantial changes, sometimes backward incompatible, in coordinate reference
  system and coordinate transformations have been introduced per
  https://trac.osgeo.org/gdal/wiki/rfc73_proj6_wkt2_srsbarn
    * OSRImportFromEPSG() takes into account official axis order.
      Traditional GIS-friendly axis order can be restored with
      OGRSpatialReference::SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
    * Same for SetWellKnownGeogCS("WGS84") / SetFromUserInput("WGS84")
    * removal of OPTGetProjectionMethods(), OPTGetParameterList() and OPTGetParameterInfo()
      No equivalent.
    * removal of OSRFixup() and OSRFixupOrdering(): no longer needed since objects
      constructed are always valid
    * removal of OSRStripCTParms(). Use OSRExportToWktEx() instead with the
      FORMAT=SQSQL option
    * exportToWkt() outputs AXIS nodes
    * OSRIsSame(): now takes into account data axis to CRS axis mapping, unless
      IGNORE_DATA_AXIS_TO_SRS_AXIS_MAPPING=YES is set as an option to OSRIsSameEx()
    * ogr_srs_api.h: SRS_WKT_WGS84 macro is no longer declared by default since
      WKT without AXIS is too ambiguous. Preferred remediation: use SRS_WKT_WGS84_LAT_LONG.
      Or #define USE_DEPRECATED_SRS_WKT_WGS84 before including ogr_srs_api.h

Out-of-tree drivers:
* GDALDataset::GetProjectionRef() made non-virtual.
  Replaced by GetSpatialRef() virtual method.
  Compatibility emulation possible by defining:
    const char* _GetProjectionRef() override; // note leading underscore
    const OGRSpatialReference* GetSpatialRef() const override {
        return GetSpatialRefFromOldGetProjectionRef();
    }

* GDALDataset::SetProjection() made non-virtual.
  Replaced by SetSpatialRef() virtual method.
  Compatibility emulation possible by defining:
    CPLErr _SetProjection(const char*) override; // note leading underscore
    CPLErr SetSpatialRef(const OGRSpatialReference* poSRS) override {
        return OldSetProjectionFromSetSpatialRef(poSRS);
    }

* GDALDataset::GetGCPProjection() made non-virtual.
  Replaced by GetGCPSpatialRef() virtual method.
  Compatibility emulation possible by defining:
    const char* _GetGCPProjectionRef() override; // note leading underscore
    const OGRSpatialReference* GetGCPSpatialRef() const override {
        return GetGCPSpatialRefFromOldGetGCPProjection();
    }

* GDALDataset::SetGCPs(..., const char* pszWKT) made non-virtual.
  Replaced by SetGCPs(..., const OGRSpatialReference* poSRS) virtual mode.
    CPLErr _SetGCPs( int nGCPCount, const GDAL_GCP *pasGCPList,
                    const char *pszGCPProjection ) override; // note leading underscore
    CPLErr SetGCPs( int nGCPCountIn, const GDAL_GCP *pasGCPListIn,
                    const OGRSpatialReference* poSRS ) override {
        return OldSetGCPsFromNew(nGCPCountIn, pasGCPListIn, poSRS);
    }

MIGRATION GUIDE FROM GDAL 2.3 to GDAL 2.4
-----------------------------------------

1) Out-of-tree drivers: RawRasterBand() constructor changes

RawRasterBand now only accepts a VSILFILE* file. Consequently the void* fpRaw
argument has become a VSILFILE* one. And the bIsVSIL = FALSE argument has
been removed. The int bOwnsFP = FALSE has seen its default value suppressed,
and has seen its type changed to the RawRasterBand::OwnFP::YES/NO enumeration,
to detect places where your code must be changed.

Caution: code like RawRasterBand(..., bNativeOrder, TRUE) must be changed to
RawRasterBand(..., bNativeOrder, RawRasterBand::OwnFP::NO, the TRUE value
being the bIsVSIL value, and the default argument being bOwnsFP == FALSE.

MIGRATION GUIDE FROM GDAL 2.2 to GDAL 2.3
-----------------------------------------

1) RFC 70: Guessing output format from output file name extension for utilities

Link: https://trac.osgeo.org/gdal/wiki/rfc70_output_format_guess

Before GDAL 2.3, if not specifying the output format to utilities, GeoTIFF or
Shapefile were assumed for most utilities. Now, the output format will be
guessed from the output filename extension. This might break usages where
non-standard extensions are used for GeoTIFF or Shapefile output when -f/-of is
not specified (but warnings were already emitted in such situations).

2) RFC 68: C++11 Compilation requirement

Link: https://trac.osgeo.org/gdal/wiki/rfc68_cplusplus11

GDAL now requires a C++11 compatible compiler. External code using GDAL C++ API
will also need to enable at least C++11 compilation mode, if the compiler
defaults to C++98/C++03.

3) Stricter const-ness in OGRGeomFieldDefn, OGRFeatureDefn and OGRFeature
   classes, impacting out-of-tree drivers that subclass them.

   The following methods are now const qualified:

     OGRGeomFieldDefn class:
        virtual OGRSpatialReference* GetSpatialRef() const

     OGRFeatureDefn class:
        virtual const char* GetName() const
        virtual int GetFieldCount() const
        virtual int GetFieldIndex(const char*) const
        virtual int GetGeomFieldCount() const
        virtual int GetGeomFieldIndex(const char*) const
        virtual OGRwkbGeometryType GetGeomType() const
        virtual OGRFeatureDefn* Clone() const
        virtual int IsGeometryIgnored() const
        virtual int IsSame(const OGRFeatureDefn*) const // argument is const now too

     OGRFeature class:
        virtual OGRBoolean Equal(const OGRFeature*) const // argument is const now too
        virtual const char* GetStyleString() const
        virtual OGRStyleTable* GetStyleTable() const

    The following virtual methods, offering const alternatives to their
    non-const equivalent methods, should be overloaded if the non-const
    method is overloaded.

     OGRFeatureDefn class:
        virtual const OGRFieldDefn* GetFieldDefn(int) const
        virtual const OGRGeomFieldDefn* GetGeomFieldDefn(int) const


MIGRATION GUIDE FROM GDAL 2.1 to GDAL 2.2
-----------------------------------------

A) RFC 64: Triangle, Polyhedral surface and TIN

Link: https://trac.osgeo.org/gdal/wiki/rfc64_triangle_polyhedralsurface_tin

Vector drivers can now return geometries of type wkbPolyhedralSurface, wkbTIN
and wkbTriangle; and their Z, M and ZM variants (as well as for the type of
geometry fields). Client code, as well as out-of-tree drivers that support
writing geometries, must be ready to deal with them.

B) RFC 67: Null values in OGR

Link: https://trac.osgeo.org/gdal/wiki/rfc67_nullfieldvalues

Previously, the "unset" state of a field was used both for a unset state
(ie no information for the field of the feature) or the NULL state of the
field. Now there is OGR_F_IsFieldSet() / OGRFeature::IsFieldSet() for the
unset state, and a new OGR_F_IsFieldNull() / OGRFeature::IsFieldNull() for the
new NULL state. Code that used OGR_F_IsFieldSet() / OGRFeature::IsFieldSet()
should also test the NULL state, otherwise empty strings or 0 numeric values
will be returned. A convenient way of migrating is to replace the use of
OGR_F_IsFieldSet() / OGRFeature::IsFieldSet() by OGR_F_IsFieldSetAndNotNull() /
OGRFeature::IsFieldSetAndNotNull() if there is no need to distinguish both
states.
On the writing side, a few drivers will now distinguish between the unset
and null state, namely GeoJSON, CouchDB, Cloudant, MongoDB, ElasticSearch and
GML. For example, for the GeoJSON driver, in GDAL 2.1 or before, a unset field
was written as field_name: null. Starting with GDAL 2.2, only fields explicitly
set as null with OGR_F_SetFieldNull() will be written with a null value.
Unset fields of a feature will not be present in the corresponding JSon feature
element.

MIGRATION GUIDE FROM GDAL 2.0 to GDAL 2.1
------------------------------------------

A) RFC 61: Support for measured geometries

Link: https://trac.osgeo.org/gdal/wiki/rfc61_support_for_measured_geometries

The OGRwkbGeometryType enumeration has been extended with new values for the
M and ZM variants of the geometry types. Client code may have to be upgraded
to take into account those new values. Note that the wkbPolyhedralSurface, wkbTIN
and wkbTriangle types and their Z, M and ZM variants, have also been introduced
as a provision for a potential support in a future version (they are unused in
OGR core and drivers for now).

Previously the ESRI Shapefile driver read XYM data as XYZ. Now it is read
as XYM.

MIGRATION GUIDE FROM GDAL 1.11 to GDAL 2.0
------------------------------------------

This file documents backwards incompatible changes. You are strongly encouraged
to read the relevant RFCs for details and rationale for those changes.

Changes to the Perl bindings API are listed in swig/perl/Changes-in-the-API-in-2.0.

A) RFC 46: Unification of GDAL and OGR driver models

Link: http://trac.osgeo.org/gdal/wiki/rfc46_gdal_ogr_unification

C++ API:

  * OGRSFDriverRegistrar and OGRSFDriver are now deprecated. Use GDALDriverManager
    and GDALDriver instead.

  * The following methods from OGRSFDriverRegistrar are removed : Open(),
    OpenShared(), ReleaseDataSource(), DeregisterDriver(), AutoLoadDrivers()
    GetDriver() and GetDriverByName() now return a GDALDriver* instance.

  * OGRDataSource::CreateLayer() specialized implementations should be renamed
    as ICreateLayer() to benefit from layer creation options validation.

  * OGRLayer::GetInfo() has been removed.

  * All methods of OGRDataSource have been transferred to GDALDataset, except
    SyncToDisk() that should now be implemented as FlushCache() in drivers.

  * GDALOpenInfo::papszSiblingFiles member is now private. Use the new
    GetSiblingFiles() method instead.

  * GDALOpenInfo::fp member is replaced by fpL member of type VSILFILE*.

  * OGRSFDriver::CopyDataSource() has been removed.

  * GDALDriverManager::GetHome() and SetHome() have been removed.

Out-of-tree drivers :

  * Read RFC 46 for the needed changes. Changes in GDALOpenInfo will impact GDAL
    drivers. GDAL drivers should also declare SetMetadataItem( GDAL_DCAP_RASTER, "YES" ).
    OGRDataSource::CreateLayer() and SyncToDisk() changes will affect OGR drivers.

Behavior changes :

  * GDALDriverManager::GetDriverCount() and GetDriver() return both raster and
    vector drivers. The nature of a driver can be tested with the GDAL_DCAP_RASTER
    and GDAL_DCAP_VECTOR driver metadata item.

  * GetRefCount() starts at 1 for OGRDataSource instead of 0.

B) RFC 49: Curve geometries

Link: http://trac.osgeo.org/gdal/wiki/rfc49_curve_geometries

C/C++ API :

  * Use of wkb25DBit macro is strongly discouraged, as not compatible with new
    geometry types. Use wkbFlatten(), wkbHasZ(), wkbSetZ() instead
  * OGRwkbGeometryType enumeration has new values.

Behavior changes :

  * GML, NAS, WFS, PostGIS, VRT, GeoPackage and CSV drivers can return non-linear geometries.
    Applications that do not wish to get such geometries can call
    OGRSetNonLinearGeometriesEnabledFlag(FALSE)

Out-of-tree drivers :

  * Read RFC 49 for the needed changes. CreateFeature() and SetFeature() virtual
    methods must be renamed ICreateFeature() and ISetFeature().

C) RFC 51: RasterIO() improvements : resampling and progress callback

Link: http://trac.osgeo.org/gdal/wiki/rfc51_rasterio_resampling_progress

Out-of-tree drivers :

  * Read RFC 51 for the needed changes. GDALRasterBand and GDALDataset::IRasterIO()
    take a new GDALRasterIOExtraArg* psExtraArg argument.
    GDALRasterBand and GDALDataset::RasterIO() take a new
    GDALRasterIOExtraArg* psExtraArg argument

D) RFC 31: OGR 64bit Integer Fields and FIDs

Link:http://trac.osgeo.org/gdal/wiki/rfc31_ogr_64

C++ API:
  * OGRLayer::GetFeature(), OGRLayer::DeleteFeature(), OGRLayer::SetNextByIndex() take a GIntBig instead of a long
  * OGRFeature::GetFID() and OGRLayer::GetFeatureCount() now returns a GIntBig

C API:
  * OGR_L_GetFeature(), OGR_L_DeleteFeature(), OGR_L_SetNextByIndex() take a GIntBig instead of a long
  * OGR_F_GetFID() and OGR_L_GetFeatureCount() now returns a GIntBig

Behavior changes :
  * OFTInteger64 and OFTIntegerList64 can be returned whereas OGRFieldType is returned.

Out-of-tree drivers :
  * Virtual method signature change: OGRLayer::GetFeature(), OGRLayer::DeleteFeature(),
    OGRLayer::SetNextByIndex() take a GIntBig argument instead of a long
  * Virtual method signature change: OGRLayer::GetFeatureCount() now returns a GIntBig
  * OGRFeature::GetFID() returns a GIntBig

E) RFC 52: Strict OGR SQL quoting

Link: http://trac.osgeo.org/gdal/wiki/rfc52_strict_sql_quoting

No API changes

Behavior changes:
  * Identifiers, i.e column names or table names, can no longer be quoted with
    single quote characters, but must use double quote characters if quoting is
    needed, conforming with SQL 92 syntax. Failure to do the change will not
    necessarily need to verbose errors at runtime since an expression like
    WHERE 'a_column_name' = 'a_value' will now always evaluate to FALSE whereas
    it would have been interpreted as WHERE "a_column_name" = 'a_value" if
    a_column_name was indeed a column name.

F) RFC 53: OGR not-null constraints and default values

Link: http://trac.osgeo.org/gdal/wiki/rfc53_ogr_notnull_default

API changes:
    * OGRFieldDefn::SetDefault() now takes a const char* as argument.
      OGRFieldDefn::GetDefaultRef() removed and replaced by GetDefault() that
      returns a const char*

G) RFC 54: Dataset transactions

Link: http://trac.osgeo.org/gdal/wiki/rfc54_dataset_transactions

Only API additions.

Behavior changes:
  * As described in the RFC, subtle behavior changes can be observed with the PG driver,
    related to implicit transactions that were flushed before and are no longer now,
    but this should hopefully be restricted to non-typical use cases. So some cases that "worked" before might
    no longer work, but the new behavior should hopefully be more understandable.

  * The PG and SQLite drivers could accept apparently nested calls to StartTransaction()
    (at the layer level). This is no longer possible since they are now redirected
    to dataset transactions, that explicitly do not support it.

H) RFC 55: Refined SetFeature() and DeleteFeature() semantics

Link: http://trac.osgeo.org/gdal/wiki/rfc55_refined_setfeature_deletefeature_semantics

Behavior changes:
    * Drivers will now return OGRERR_NON_EXISTING_FEATURE when calling SetFeature()
      or DeleteFeature() with a feature id that does not exist.

I) RFC 56:

Link: https://trac.osgeo.org/gdal/wiki/rfc56_millisecond_precision

API/ABI changes:

  * OGRField.Date structure has now a Reserved field that must be set to 0 when
    using the OGRFeature::SetField( int i, OGRField * puValue ) method.
    The "GByte Second" field is now a "float Second".

  * OGRFeature::SetField( int i, int nYear, int nMonth, int nDay,
                          int nHour=0, int nMinute=0, float fSecond=0.f,
                          int nTZFlag = 0 )
    and the variant that take a const char* as first argument now accept a
    floating-point number for seconds.

API additions :

    * OGRFeature::GetFieldAsDateTime( int i,
                                     int *pnYear, int *pnMonth, int *pnDay,
                                     int *pnHour, int *pnMinute, float *pfSecond,
                                     int *pnTZFlag );

    * OGR_F_GetFieldAsDateTimeEx() and OGR_F_SetFieldDateTimeEx() are added.

Driver related changes:

    * The following functions, mainly used by driver implementations, have
      seen their signature change :

        int CPL_DLL OGRParseXMLDateTime( const char* pszXMLDateTime,
                                        OGRField* psField );
        int CPL_DLL OGRParseRFC822DateTime( const char* pszRFC822DateTime,
                                            OGRField* psField );
        char CPL_DLL * OGRGetRFC822DateTime(const OGRField* psField);
        char CPL_DLL * OGRGetXMLDateTime(const OGRField* psField);

Behavior changes:

    * OGRFeature::GetFieldAsString() will now output milliseconds if a DateTime/Time
      field has such precision.
    * Drivers will now output milliseconds if a DateTime/Time field has such precision.

J) RFC 57: 64-bit bucket count for histograms

Link: https://trac.osgeo.org/gdal/wiki/rfc57_histogram_64bit_count

C++ API:
  * GDALRasterBand::GetHistogram() and GDALRasterBand::SetDefaultHistogram() take a GUIntBig* instead of a int* for bucket counts.
  * GDALRasterBand::GetDefaultHistogram() takes a GUIntBig** instead of a int** for bucket counts.
  * GDALRasterBand::GetRasterSampleOverview() takes a GUIntBig instead of int.

C API:
  * GDALGetRasterHistogramEx(), GDALGetDefaultHistogramEx() and GDALSetDefaultHistogramEx() are added
    and deprecate the old interfaces.
  * GDALGetRasterSampleOverviewEx() is added.

Out-of-tree drivers :
  * See the virtual method API changes mentioned above in the C++ API paragraph.

MIGRATION GUIDE FROM GDAL 1.10 to GDAL 1.11
-------------------------------------------

This file documents backwards incompatible changes.

C++ API:

  * GDALRasterAttributeTable is now an abstract class.
    See http://trac.osgeo.org/gdal/wiki/rfc40_enhanced_rat_support
    The functionality of GDAL 1.X GDALRasterAttributeTable is now in
    GDALDefaultRasterAttributeTable.

OGR drivers :

  * Due to RFC 41, if a OGR driver calls SetGeomType(wkbNone) on a layer,
    it will be impossible to affect geometries to features of that layer.
    This worked before, although it was inconsistent, but it does no longer now.
    In the development of RFC 41, the CSV and VRT drivers have been upgraded
    to fix such errors.

Changes that should likely not impact anybody :

   * OGRGeometry::exportToGEOS() and OGRGeometryFactory::createFromGEOS() now
     take a GEOSContextHandle_t argument ( GEOS >= 3.1.0 )

   * OGRGeometryFactory::getGEOSGeometryFactory() has been removed.
     This method returned NULL since 2006
     ( http://trac.osgeo.org/gdal/changeset/9899/trunk/ogr/ogrgeometryfactory.cpp )