[geos-devel] WkbReader and Z-geometries
mtnclimb at telus.net
Wed Aug 3 20:24:32 EDT 2011
The EWKB that JTS and GEOS implement is based on the PostGIS EWKB
specification (which predates the SQL/MM spec, I think.)
I don't have a good reference for the PostGIS spec - it would be nice if
there was one online somewhere (hint, hint).
It might be nice if JTS/GEOS supported the SQL/MM spec as well. Do you
have a reference available for the spec?
On 8/3/2011 4:19 AM, Oyvind Idland wrote:
> i am trying to read WKB chunks based on the iso SQL/MM part3 spec.
> However, this doesn't seem to work.
> From the WkbReader source code doc:
> "This implementation supports the extended WKB standard for
> representing 3-dimensional coordinates. The presence of 3D coordinates
> is signified by setting the high bit of the wkbType word."
> Which extended WKB standard is being refered to here ?
> For example, In the SQL/MM spec, various point types are defined as
> the following unsigned values (not hex):
> <wkbpoint> 1
> <wkbpointz> 3000001
> <wkbpointzm> 2000001
> <wkbpointm> 4000001
> However, in the WkbReader.cpp the following logic is used:
> int typeInt = dis.readInt();
> int geometryType = typeInt & 0xff;
> bool hasZ = ((typeInt & 0x80000000) != 0);
> if (hasZ) inputDimension = 3;
> else inputDimension = 2; // doesn't handle M currently
> Is there any plans to implement support for SQL/MM ? (I can volunteer
> for a patch, if desired)
> -- Oyvind
> geos-devel mailing list
> geos-devel at lists.osgeo.org
> No virus found in this message.
> Checked by AVG - www.avg.com <http://www.avg.com>
> Version: 10.0.1390 / Virus Database: 1518/3807 - Release Date: 08/03/11
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the geos-devel