Bill, We've looked at the VM solution as well. I agree that they are basically the same (the set we ran showed some variances around the outer limits of the set of points). However, I wouldn't say there are no flaws if it doesn't work with unprojected coordinates unless they document it as such.
Any way, it looks like the answer is to use a State Plane or UTM system for now. Thanks, Gary. Bill Thoen wrote: > > 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 -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 2464
