[Gdal-dev] OCI-geometry recognition

[Frank Warmerdam]

Stephan Holl wrote:
> Exporting this as WKT it says it is LINESTRING(x, y, z).
> 
> So the mystery-value of 2147483650 seems strange. Is this a bug in OGR?
> 
> Same applies to point and geometry layers:
> WKB for points:   2147483649
> WKB fr lines:     2147483650
> WKB for polygons: 2147483651

Stephan,

This is the list of enumerated values for geometry types in OGR:

typedef enum
{
     wkbUnknown = 0,             /* non-standard */
     wkbPoint = 1,               /* rest are standard WKB type codes */
     wkbLineString = 2,
     wkbPolygon = 3,
     wkbMultiPoint = 4,
     wkbMultiLineString = 5,
     wkbMultiPolygon = 6,
     wkbGeometryCollection = 7,
     wkbNone = 100,              /* non-standard, for pure attribute records */
     wkbLinearRing = 101,        /* non-standard, just for createGeometry() */
     wkbPoint25D = 0x80000001,   /* 2.5D extensions as per 99-402 */
     wkbLineString25D = 0x80000002,
     wkbPolygon25D = 0x80000003,
     wkbMultiPoint25D = 0x80000004,
     wkbMultiLineString25D = 0x80000005,
     wkbMultiPolygon25D = 0x80000006,
     wkbGeometryCollection25D = 0x80000007
} OGRwkbGeometryType;

So, what you are seeing is the 2.5D (x,y,z) forms of the geometries.
For applications that don't care to differentiate, I normally use the
wkbFlatten() macro on the values to reduce them to the simple 2D versions.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org