I guess that you are right about the midlines between different zones. These midlines will follow the midline of the centroid, not the actual border.
Creating points for all nodes in each region could be a way of solving it. I'm not sure how good MapInfo will handle the creation of voronoi regions from points placed exactly in the same spot. This will be the case where to regions share a common line. If MapInfo doesn't handle this very well, you'll need to erase the points created from shared lines, so that the only nodes created are the ones where a paddock hasn't any heighbour. I guess this issue was discussed lately at MapInfo-L Peter Horsb�ll M�ller GIS Developer Geographical Information & IT COWI A/S Rug�rdsvej 55 DK-5000 Odense Denmark Tel +45 6313 5013 Direct +45 6313 5008 Mob +45 5156 1045 Fax +45 6313 5090 E-mail [EMAIL PROTECTED] http://www.cowi.dk COWI GIS konference afvikles i dagene d. 2.-3. september. Se yderligere oplysninger p� www.cowi.dk/Div04/Profiles/nyheder.asp > -----Original Message----- > From: Robert Crossley [mailto:[EMAIL PROTECTED] > Sent: Thursday, July 10, 2003 9:05 AM > To: Peter Horsb�ll M�ller > Cc: MapInfo List > Subject: Re: MI-L Making zones. > > > Thanks Peter, > > I'll try this, this should work,but am not sure if the edges > of the veroni > regions would follow the mid line between paddocks of > different zones, but > would follow the midline between their centroids. Be worth > seeing how it > looks. > > You have given me another idea though, maybe if I were to > create veroni > regions from a file that had points created from all the > nodes? Then merge > those on zones...... > > Big process, but possible. > > R > > On Thu, 10 Jul 2003 07:48:13 +0200, Peter Horsb�ll M�ller > <[EMAIL PROTECTED]> > wrote: > > > How about this solution: > > > > 1. Make a new table containing a copy of your paddocks table > > structure. Let's call it ZoneVoronoi 2. Open this this, add it to a > > map and make it editable 3. Now we need another copy of the > paddocks > > table, Let's call it ZonePoints > > 3. Now we have to convert the regions in ZonePoints to > points to be able > > to > > create voronoi regions using these: > > a. Open the MapBasic window and enter the line below followed by > > Enter > > Update ZonePoints set OBJ = CreatePoint(CentroidX(OBJ), > > CentroidY(OBJ)) > > 4. Now select all records in the ZonePoints table (this can be made > > easily > > by selecting a single record, pushing the Invert Selection and then > > reselecting the single record again while holding down the Shift key > > 5. Now we want to create voronoi regions using these points > and insert > > these > > regions into the ZoneVoronoi > > 6. Now we have to delete those parts of these voronoi > regions that are > > within an existing paddock: > > -Select all the voronoi regions > > -Set these to target objects > > -Select all existing paddocks > > -Use the menu item Objects > Erase to erase overlapping areas > > 7. Now we have to insert the existing paddocks in the > ZoneVoronoi. Select > > all paddocks, Use the keys CTRL+C to copy and CTRL+V to insert into > > ZoneVoronoi. > > 8. And finally we want to combine the paddocks that have > the same zone id > > into a new table called Zones > > -Choose Table Combine Objects using column > > -Choose ZoneVoronoi as input table, your zone id column > as column > > and choose the insert the result into a new table > > -Make sure this new table at least holds the column for > the zone id > > and tell MapInfo to read this value from the column holding > this value > > in > > the ZoneVoronoi table. > > > > Et voila ! > > > > HTH, > > > > Peter Horsb�ll M�ller > > GIS Developer > > Geographical Information & IT > > COWI A/S > > Rug�rdsvej 55 > > DK-5000 Odense > > Denmark > > Tel +45 6313 5013 > > Direct +45 6313 5008 > > Mob +45 5156 1045 > > Fax +45 6313 5090 > > E-mail [EMAIL PROTECTED] > > http://www.cowi.dk > > COWI GIS konference afvikles i dagene d. 2.-3. september. > > Se yderligere oplysninger p� www.cowi.dk/Div04/Profiles/nyheder.asp > > > > > > > >> -----Original Message----- > >> From: Robert Crossley [mailto:[EMAIL PROTECTED] Sent: Thursday, > >> July > >> 10, 2003 2:49 AM > >> To: MapInfo List > >> Subject: MI-L Making zones. > >> > >> > >> Hi all, > >> > >> I have a file with about 1500 farms composed of about > 60000 paddocks, > >> usually separated spatially. These are grouped into 47 > reporting zones. > >> > >> Is there a function or program that can create a map of > those zones. > >> I > >> want to create a table that has spatial representations of > those zones, > >> with the spatial objects contiguous - and would prefer not > to have to > >> digitise those boundaries. > >> > >> When I simply do a merge using column, I get the same separate > >> paddock > >> outlines (except those where the paddocks touch), with 47 complex > >> objects, and a 4MB file. > >> > >> Convex Hull makes overlapping regions. > >> > >> Veroni ignores the extent of the paddocks when creating > its objects. > >> > >> Buffering takes forever, and overlaps neighbouring zones anyway. > >> > >> What I really want is veroni polygons that are created > using regions > >> rather than points. > >> > >> TIA > >> > >> R > >> > >> -- > >> > >> Robert Crossley Agtrix P/L > >> 9 Short St > >> New Brighton 2483 > >> Far Southern Queensland > >> AUSTRALIA > >> > >> P: 02 6680 1309 > >> F: New Connection > >> M: 0419 718 642 > >> E: [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: 7568 > >> > > > > > > -- > > Robert Crossley Agtrix P/L > 9 Short St > New Brighton 2483 > Far Southern Queensland > AUSTRALIA > > P: 02 6680 1309 > F: New Connection > M: 0419 718 642 > E: [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: 7575
