[postgis-devel] WKT and Wikipedia

[Paul Ramsey]

Yes, handling POINT M, POINT Z, and POINT ZM is a good thing for 1.4.
That's an addition to the parser (I can put my new lex/yacc book to
use :). The hard question is what to *emit* in response to an
ST_AsText() :)

P.

PS - those are the ISO wkt forms too.

On Fri, Jun 27, 2008 at 4:42 PM, Kevin Neufeld <kneufeld at refractions.net> wrote:
> So, the 1.2 OGC specs require that the WKT of Z, M, and ZM be:
> POINT <point text>
> POINT Z <point z text>
> POINT M <point m text>
> POINT ZM <point zm text>
>
> PostGIS has:
> POINT <point text> | <point z text>
> POINTM <point m text> | <point zm text>
>
> To me, this means PostGIS is not entirely OGC compliant. (ie. PostGIS can't
> parse an OGC compliant WKT string)
>
> postgis=# SELECT 'POINT ZM(0 0 0 0)'::geometry;
> ERROR:  parse error - invalid geometry
>
> Same goes for the textual representation of other geometries.
> ie. LINESTRING ZM (...)
>
> Should we add this to the TODO list for 1.4?  Or is there a specs gray area
> ... that we're compliant enough.
>
> -- Kevin
>
> Martin Davis wrote:
>>
>> Actually the latest SFS 1.2 spec does include a spec for 2D measured, 3D &
>> 3D measured WKT.  See here:
>>
>> http://www.opengeospatial.org/standards/sfa
>>
>> (This is also referenced on the wiki page)
>>
>>
>>
>> Kevin Neufeld wrote:
>>>
>>> I just came across this page:
>>> http://en.wikipedia.org/wiki/Well-known_text
>>>
>>> I think this page is incorrect, misleading, and contains typos.  It is my
>>> understanding that the OGC specs on WKT does *not* include 3D and 4D
>>> definitions.  It is a PostGIS extension to use Z, M, or ZM. Or am I off on
>>> this?
>>> (http://portal.opengeospatial.org/files/?artifact_id=829) (section
>>> 3.2.5.2)
>>>
>>> I don't have an account to correct this.  Does any here have one?  Do we
>>> care?
>>>
>>> Should the new PostGIS docs reference such pages, or point to only the
>>> OGC specs?
>>>
>>> -- Kevin
>>> _______________________________________________
>>> postgis-devel mailing list
>>> postgis-devel at postgis.refractions.net
>>> http://postgis.refractions.net/mailman/listinfo/postgis-devel
>>>
>>
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