[fdo-internals] Parsing WKT geoemtry with measure/dimensionality

Orest Halustchak orest.halustchak at autodesk.com
Tue Feb 26 08:21:24 EST 2008


Frank is correct that the FGF format was defined prior to the OGC working on the updated spec for wkb and wkt to support Z and M. I agree that FDO should be enhanced to support the new OGC spec. I'll add an entry to the FDO Futures wiki page for it and hopefully at some point someone will put together an RFC for it.

What other systems do we know about that have added support for the updated Simple Features Spec?


-----Original Message-----
From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Frank Warmerdam (External)
Sent: Monday, February 25, 2008 4:27 PM
To: FDO Internals Mail List
Subject: Re: [fdo-internals] Parsing WKT geoemtry with measure/dimensionality

Simon Pelicon wrote:
> Hi!
> I have a problem parsing WKT geometry with M or Z dimension.
> For example in WKT documentation specification, point with M is defined
> as in the example below:
> Point M (10 10 40)
> But parsing this to geometry in FDO returns this error:
> m_cause = 0x01693a30 {m_message=0x01693a80
> "(.\Src\Geometry\Parse\ParseFgft.cpp: 88) String is not a valid FGF
> string. "
> Fdo documentation says that: The Autodesk extension to WKT, referred to
> as FGF Text, is a superset of WKT
> (that is, you can enter WKT as valid FGF Text strings). Dimensionality
> is optional. It can be XY, XYM, XYZ, or XYZM.
> I am confused about dimensionality specification now.
> WKT specification puts only M or ZM ,but FDO requires XY in front of M
> or ZM.


I think the problem is that you are looking at the "new" Simple Features
geometry specification, while FDO's FGF parser was written to the old
one.  The new specification was only released within the last year I

It certainly would be desirable (in my mind) for the FDO geometry parser
to support both variations to the extent possible.

BTW, the old simple features geometry specification did not include
Z or M dimensions though there were some common approaches to supporting
them in use in the wild.

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

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