Paul, I would recommend that you use the Distance Calculator tool. With this tool you can find the nearest object in one table to each object in another table. You would need MapInfo 8.0 to be able to do this though.
If you don't have MapInfo 8.0, I have nmade a tool called NearestObject that can be found on Directionsmag.com under Tools. Both tools will give you a result table containing an id from both table and a line showing the "distance". The Distance Calculator also updates a column with the distance. HTH, Peter Horsbøll Møller GIS Developer, MTM Geographical Information & IT COWI A/S Odensevej 95 DK-5260 Odense S. Denmark Tel +45 6311 4900 Direct +45 6311 4908 Mob +45 5156 1045 Fax +45 6311 4949 E-mail [EMAIL PROTECTED] http://www.cowi.dk/gis -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Spencer Simpson Sent: Friday, April 28, 2006 2:51 PM To: [EMAIL PROTECTED]; 'Paul Donnelly' Cc: mapinfo-l@lists.directionsmag.com Subject: RE: [MI-L] Updating column with number of objects nearest apolyline... Line-based Voronoi polygons would be nice, wouldn't they? There's a way to approximate them by generating intermediate points but I'm not sure the cure isn't worse than the disease... Spencer ________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Lars I. Nielsen (GisPro) Sent: Thursday, April 27, 2006 4:48 PM To: Paul Donnelly Cc: mapinfo-l@lists.directionsmag.com Subject: Re: [MI-L] Updating column with number of objects nearest apolyline... Hi Poul, Would a feasible way not be to "explode" your polylines to node point objects, and generate voronoi polygons around these points ? Preserving some sort of "polyline ID" for each polygon. That way you could find the points closest to any node, and sum the counts using the "polyline ID" as aggregator. Unless your polyline are really weird, it ought to give you a reasonable result, or at least one that only counts single incident points once. Best regards / Med venlig hilsen Lars I. Nielsen GisPro Paul Donnelly wrote: Hello all! Was wondering if anyone can help me out with a little problem I need help in solving? Basically, I have two MapInfo tables - One table containing polylines representing road networks, and a second table containing point objects representing the locations of road accidents. I need a method of calculating the sum of accidents per road link. Previously I had buffered the polylines and then simply used the 'update column' function to sum up the number of objects within the buffer. The problem with this though was that where two polylines meet at a junction there was an overlap with the buffers and so when an accident point falls in this overlap it is double counted within both overlapping buffers. With small sections of road networks I simply edited the buffers to remove the overlap and then used the update column method. The problem now is that I have a lot of road newtork data and if I were to go round and remove each overlap for each individual section I'd still be here this time next year! So, ideally I need a method of assigning accident points to a single road link which is nearest. Then I need to update a column within the link table to count the number of accidents assigned to each particular road section. Any help solving this problem would much appreciated! Thanks in advance, Paul Donnelly Email: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> ********************************************************************** This message contains information which is confidential and may also be privileged. It is for the exclusive use of the intended recipient(s). If you are not the intended recipient(s) please note that any form of distribution, copying or use of this communication or the information in it is strictly prohibited and may be unlawful. If you have received this communication in error please return it to the sender and then delete the email and destroy any copies of it. Thank you. Hyder cannot guarantee that this message or any attachment is virus-free or has not been intercepted or changed. Any opinions or other information in this message that do not relate to the official business of the Company are neither given nor endorsed by it. ********************************************************************** ________________________________ _______________________________________________ MapInfo-L mailing list MapInfo-L@lists.directionsmag.com http://www.directionsmag.com/mailman/listinfo/mapinfo-l _______________________________________________ MapInfo-L mailing list MapInfo-L@lists.directionsmag.com http://www.directionsmag.com/mailman/listinfo/mapinfo-l _______________________________________________ MapInfo-L mailing list MapInfo-L@lists.directionsmag.com http://www.directionsmag.com/mailman/listinfo/mapinfo-l
