Looks to be free for non-commerical use. http://www.cs.man.ac.uk/~toby/gpc/
On Wed, May 2, 2012 at 2:56 PM, Judd Taylor <[email protected]>wrote: > I have an interface to the GPC polygon clipping library for PDL. > Unfortunately, GPU isn't GPL. We've had to buy a commercial license to use > it, so it's not really a candidate for the PDL core... > > -Judd > ____________________________ > Judd Taylor > Software Engineer > > Orbital Systems, Ltd. > 3807 Carbon Rd. > Irving, TX 75038-3415 > > [email protected] > (972) 915-3669 x127 > > ________________________________________ > From: Chris Marshall [[email protected]] > Sent: Wednesday, May 02, 2012 1:55 PM > To: Steven Lembark > Cc: [email protected] > Subject: Re: [Perldl] Geometry, anyone? > > PDL-2.4.10 and later include a pnpoly routine which may > be of use: > > pdldoc pnpoly > Module PDL::Image2D > pnpoly > 'points in a polygon' selection from a 2-D piddle > > $mask = pnpoly($x, $y, $px, $py); > > For a closed polygon determined by the sequence of points in {$py,$py} > the output of pnpoly is a mask corresponding to whether or not each > coordinate (x,y) in the set of test points, {$x,$y}, is in the interior > of the polygon. This is the 'points in a polygon' algorithm from > <http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html > > > and vectorized for PDL by Karl Glazebrook. > > # define a 3-sided polygon (a triangle) > $px = pdl( 3, 20, 34 ); > $py = pdl( 3, 20, 3 ); > > $img = zeros(40, 40); # create test image > $x = $img->xvals; # get x pixel coords > $y = $img->yvals; # get y pixel coords > > # $tri is 0 everywhere except for points in polygon interior > $tri = pnpoly($x,$y,$px,$py); > > As for more, PDL has a lot of tools to make such > computations work (implementable and with good > performance). The PDL home page is a good place > to start for more information: http://pdl.perl.org > > --Chris > > > On Wed, May 2, 2012 at 2:49 PM, Craig DeForest > <[email protected]> wrote: > > There is a very nice algorithm in Preparata and Shamos ("Computational > Geometry"). I, for one, would love to have a PDL::PlanarGeometry package > built, to treat 2xN PDLs as collections of points on the plane. Nice > algorithms to start with would include: > > > > - area > > - hull > > - Voronoi > > - delaunay > > - polygon union > > - polygon intersection > > - polygon clean > > > > > > > > On May 2, 2012, at 12:33 PM, Steven Lembark wrote: > > > >> > >> The nice people at Oracle implement all of their OpenGIS > >> "contained within" geometry operators using bounding boxes > >> only. This makes it impossible to select non-rectangular > >> areas from a map. > >> > >> Google has gotten me nowhere looking for a PDL geometric > >> operator library that (ideally) works on OpenGIS format > >> data (WKB, WKT) or at least implements a "contains" > >> operator suitable for a point and polygon. > >> > >> I am not trying to plot anything, just get a boolean > >> outcome for, say, which state contains a given lat+long > >> or which hospital is closesest to a given point. > >> > >> Checking CPAN for PDL+GIS gives me PDL::GIS::Proj, which > >> isn't about GIS and is also pretty much dead. > >> > >> Q: Any suggestions for an implemention for selecting > >> which of a (largeish) list of polygons contain a > >> given point? > >> > >> thanks > >> > >> -- > >> Steven Lembark 3646 Flora Pl > >> Workhorse Computing St Louis, MO 63110 > >> [email protected] +1 888 359 > 3508 > >> > >> _______________________________________________ > >> Perldl mailing list > >> [email protected] > >> http://mailman.jach.hawaii.edu/mailman/listinfo/perldl > >> > > > > > > _______________________________________________ > > Perldl mailing list > > [email protected] > > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl > > _______________________________________________ > Perldl mailing list > [email protected] > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl > > _______________________________________________ > Perldl mailing list > [email protected] > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl >
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