Example Technical Committee Proposal...

Frank Warmerdam fwarmerdam at GMAIL.COM
Wed Jul 13 15:08:52 EDT 2005

On 7/13/05, Daniel Morissette <dmorissette at dmsolutions.ca> wrote:
> > Instead of writing a new WKT parser I would provide access to underlying GEOS functionality to do this and leverage the Geometry  shapeObj wrapper code that is already available.
> >
> I believe OGR is also able to ingest WKT, and mapogr.cpp has code to
> convert OGR features to shapeObj. Should we conpare the value of using
> GEOS vs OGR for this task? Frank may be in the best position to comment
> on that. This comment is mostly driven by the fact that I have not seen
> a real need for using GEOS yet (but I'm sure that will change in the
> future), and since GDAL/OGR is used by over 90% of users, OGR may be an
> easier dependency to require than adding GEOS for those who want this
> feature.


I would suggest we have an msShapeFromWKT() function that will use
either OGR's WKT converter or GEOS's depending on which is built in.
If both are available, I don't have any strong opinion on which gets used.

I haven't gone through the proposal in great detail, but I would also like
to see:
 o  the proposal include the definition of key new API functions (ie.

 o Inclusion of the reverse, an msShapeToWKT() function so that we can
    easily get the WKT representation of a shapeObj geometry.

 o There are a variety of mismatches between the WKT simple features geometry
    model and the shapeObj.  Ideally I would like to see how the mismatches will
    be handled.  I know that the OGR-WKT <-> shapeObj code has gone through
    evolution over the years for "border cases".  For instance, what does a 
    geometrycollection get changed into as a shapeObj? 

Generally speaking I am strongly in favor of the proposal, but would like
to see another revision of the proposal before approving it.   

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    | Geospatial Programmer for Rent

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