And so it seems with the Voronoi polygons. However, using a projected set of points, I got the exact same set of polygons using Vertical Mapper's "Natural Neighbor / Create Regions" menu option. I'm now pretty sure that there are no flaws in MapInfo's version.
I was mistaken earlier. Voronoi polygons are not drawn by connecting the centers of Delaunay triangles, but are made by connecting lines that perpendicularly bisect the sides of the triangles. - Bill "Warren Vick, Europa Technologies Ltd." wrote: > > Hello Bill, > > There seems to be several instances in Pro (or MapInfo technology in > general) where true spherical geometry is not used. As previously discussed > on the list, buffers (even specially Spherical ones) are also not based on > true spherical geometry. > > Regards, > Warren Vick > Europa Technologies Ltd. > http://www.europa-tech.com > > -----Original Message----- > From: Bill Thoen [mailto:[EMAIL PROTECTED]] > Sent: Friday, August 09, 2002 4:17 PM > To: Gary Schwartz > Cc: MapInfo-L > Subject: Re: MI-L Voronoi in MIPro 7.0 > > After a second look, I think maybe you are right. There are still > some problems. Voronoi polygons are created by connecting the > centers of Delauney triangles, and it appears that this is not > happening with MapInfo's Voronoi function. I'm going to poke at this > a bit more... > > Gary Schwartz wrote: > > > > Has anyone taken a close look at the Voronoi polygons generated by MI > > Pro 7.0? It looks to me like they are incorrect. The line segments > > that comprise the polygons should perpendicularly bisect the lines > > connecting the nearest neighbor points. However, they clearly do not. > > Is MapInfo using cartesian geometry to create these instead of > > spherical? Any ideas? > > > > Thanks, > > Gary. > > > > -- > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Gary Schwartz > > Director of Software Development > > Mapping Analytics > > 2 Graham Road West > > Ithaca, NY 14850 > > (585) 271-6490 > > [EMAIL PROTECTED] > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > --------------------------------------------------------------------- > > List hosting provided by Directions Magazine | www.directionsmag.com | > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > Message number: 2440 > > -- > - Bill Thoen -- - Bill Thoen ------------------------------------------------------------ GISnet, 1401 Walnut St., Suite C, Boulder, CO 80302 tel: 303-786-9961, fax: 303-443-4856 mailto:[EMAIL PROTECTED], http://www.gisnet.com/ ------------------------------------------------------------ --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 2456
