[mapserver-dev] PostGIS "curvepolygon" support

[Astrid Emde]

Hello Paul,

thanks for your answer.

I would favorite the solution b) to make the functionality generally 
available.

But just a question - we always will have the process of stroking 
PostGIS curves which will be a performance leak. Am I right?

At the moment we preprocess our data and create the strokes in the 
database in a second geom_column. So we loose no performance as we 
access the preprocessed data in our mapfiles. Solution b) will still do 
the "stroke-processing" on-the-fly.

Frank offered to implement a solution in GDAL/OGR so this would be for 
CONNECTIONTYPE OGR and the solution you suggested would be for 
CONNECTIONTYPE POSTGIS. Is this right?

Astrid


Paul Ramsey schrieb:
> Astrid,
>
> It would make sense to generally handle the curvey types in the run,
> including the compoundcurve and circularstring as forms of mapserver
> LINE types. I think your thread suggestion is correct (perhaps?) in
> that it would be "simplest" to just paper over the curve types in the
> postgis driver. This is in fact what is happening (sort of) in the
> Oracle driver already.
>
> The papering-over could take two forms.
>
> (a) We could change the SQL being send to PostGIS to ensure that
> curves are stroked (turned into equivalent linestrings) on the
> database side.
> (b) Or we could extract the stroking routines that have already been
> written in the Oracle driver to a globally accessible area, genericize
> them a little, and use them to stroke PostGIS curves in the MapServer
> code.
>
> The advantage of (b) is that the stroking routines would then be
> generically available to any other driver that needs to stroke curves.
> It would be a little more work than hacking up the SQL generated by
> the PostGIS driver to get the server to do the work of stroking.
>
> Does anyone else have interest in this issue?
>
> Paul
>
> On Mon, Nov 8, 2010 at 11:06 PM, Astrid Emde <astrid.emde at wheregroup.com> wrote:
>   
>> Hello devs,
>>
>> there was a discussion going on about PostGIS "curvepolygon" support for
>> MapServer. At the moment polygons without curves are
>> drawn, the ones with curves not.
>>
>> Here is the discussion link:
>>
>> http://osgeo-org.1803224.n2.nabble.com/PostGIS-curvepolygon-support-tt5372049.html
>>
>> One of our customers would like to sponsor this implementation and would
>> like to know how much this enhancement would cost. It would be good if you
>> could handle polygons and curevepolygons in one MapServer layer from TYPE
>> POLYGON.
>>
>> In the thread there was also the discussion about a solution which is
>> implemented in the PostGIS driver ...
>>
>>     
>>>  Curiously could this mean adding to the PostGIS driver a means of
>>>  going from curve to shapeObj? As opposed to adding a curve shape
>>>  type within MapServer.
>>>       
>> Could you please discuss a possible solution and estimate the costs? Who
>> would be the contact person concerning this enhancement?
>>
>> Maybe there are other MapServer users interested in this enhancement and
>> would also sponsor the implementation.
>>
>> --
>>
>> Best regards
>> Astrid Emde
>>
>> ----------------------------------
>>
>> Aufwind durch Wissen!
>>
>> Qualifizierte OpenSource-Schulungen
>> bei der www.foss-academy.eu
>>
>> ----------------------------------
>>
>> Astrid Emde
>> WhereGroup GmbH & Co.KG
>> Siemensstraße 8
>> 53121 Bonn
>> Germany
>>
>> Fon: +49(0)228 90 90 38 - 19
>> Fax: +49(0)228 90 90 38 - 11
>>
>> astrid.emde at wheregroup.com
>> www.wheregroup.com
>>
>> Amtsgericht Bonn, HRA 6788
>> -------------------------------
>> Komplementärin:
>> WhereGroup Verwaltungs GmbH
>> vertreten durch:
>> Olaf Knopp, Peter Stamm
>> -------------------------------
>>
>> _______________________________________________
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>>
>>     


-- 

Mit freundlichen Grüßen

Astrid Emde

----------------------------------

Aufwind durch Wissen!

Qualifizierte OpenSource-Schulungen
bei der www.foss-academy.eu

----------------------------------

 Astrid Emde
 WhereGroup GmbH & Co.KG
 Siemensstraße 8
 53121 Bonn
 Germany

 Fon: +49(0)228 90 90 38 - 19
 Fax: +49(0)228 90 90 38 - 11

 astrid.emde at wheregroup.com
 www.wheregroup.com

Amtsgericht Bonn, HRA 6788
-------------------------------
Komplementärin:
WhereGroup Verwaltungs GmbH
vertreten durch:
Olaf Knopp, Peter Stamm
-------------------------------