[gdal-dev] Ring orientation in polygons

Tim Mitchell t.mitchell at aranz.com
Sun Mar 30 20:54:09 EDT 2008


Hi,

I know the OpenGIS standard says the the exterior linear ring of a 
polygon is oriented clockwise and the interior rings are 
counterclockwise.  I also know that no all data does this.

I was just wondering if I can rely on an OGRPolygon object adhering to 
the OpenGIS standard even if the underlying data doesn't, or if I need 
to check the isClockwise() value on each ring I obtain from a polygon?

Thanks for a great library.

Kind Regards,
Tim

-- 
Tim Mitchell
Software Engineer
Applied Research Associates (NZ) Ltd. (www.aranz.com)
Ph: +64 (3) 374-6120 ext: 203
Fax: +64 (3) 374-6130
Skype: tim-mitchell



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