[Shapelib] Creating an Arc

Scott Ferguson scott at teamblue22.com
Mon Jul 27 20:26:51 PDT 2009


Thanks Frank!

I could make better sense of it if I could see the includes too, or at least
see the OGRLineString class.

Would it be possible for you to post them, or you could email them directly
to me if that is preferred?

Thanks again for your help

Regards, 


-----Original Message-----
From: shapelib-bounces at lists.maptools.org
[mailto:shapelib-bounces at lists.maptools.org] On Behalf Of Frank Warmerdam
Sent: Tuesday, July 28, 2009 2:36 PM
To: Shapelib Development
Subject: Re: [Shapelib] Creating an Arc

Sling Blade wrote:
> 
> You are correct that shapefiles cannot store curved arcs.  The normal
> technique is to approximate them as polylines.
> 
> 
> What would be great would be to learn how to approximate an Arc with
> Polylines. Do you have any code showing how this is done?
> 
> Regards

Sling,

There is some example code for converting arcs to polylines in:

  http://svn.osgeo.org/gdal/trunk/gdal/ogr/ogrsf_frmts/oci/ogrocistroke.cpp

A lot depends on how your arcs are defined.

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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