Hi. How about GEOS available at.
http://geos.refractions.net/ GEOS supports hole for clipping. I could build it in MiGW. However I've only executed demo codes. ----- Original Message ----- From: "Ross Ihaka" <[EMAIL PROTECTED]> To: "Jens Oehlschlägel" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Friday, October 24, 2003 6:13 AM Subject: Re: [R] GIS re-mapping / polygon overlap > Jens Oehlschlägel wrote: > > - is there an efficient R function that can determine the amount of area > > overlap between two general polygons (beyond gpclib) > > > > I am willing to share developed code for this problem (that's why I would > > prefer gpl code over gpclib, which is not really free) > > There is pretty cool polygon intersection algorithm available at: > > http://davis.wpi.edu/~matt/courses/clipping/4th.html > > with the code at: > > http://davis.wpi.edu/~matt/courses/clipping/code.html > > You can pick up the paper the code is based on from kai hormann's home > page (currently): > > http://vcg.isti.cnr.it/~hormann/ > > The only problem with the algorithm is that it doesn't handle holes, but > for area computations you could just join the holes to the boundary. > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help