Thanks to Steve, Uff, Spencer for having answered me. I combined the chopped up cells as suggested by Uffe and came up with the right area. Which led me to imagine that there were duplicates and there were indeed there. The problem came from a previous operation (my apologies to AreaOverlap) in which I selected cells from the grid that intersected the region. For some reason (unknown because I forgot exactly what I did) cells that intersected several polygons of the region were duplicated, maybe because I had not merged all the polygons in one region before.
With a proper selection I am getting 606 objects instead of the 651 before. That was the cause of the discrepancy. I will never learned apparently that MB statements are pretty reliable; I forgot to think about myself as the real culprit Sorry about that misconstrued question Jacques Paris -----Original Message----- From: Jacques Paris [mailto:[EMAIL PROTECTED] Sent: Monday, September 15, 2003 11:05 AM To: MIL Subject: MI-L question about areaoverlap I have a region (measures 497.8 sq km) over which I apply a 1 km square cell grid. I save only cells intersected by region (651). Then I update a column of the cell table by the "overlap" of obj with o = selection.obj of region. The sum of those "overlapped" areas gives me 518.8 sq km which seems to me to be an unacceptable result.. That the total area is calculated in spherical or cartesian does not change much. Particular condition: the region is formed of 32 polygons (some are islands) and there are some holes (lakes, rivers) I am working with 6.5 Are there any known-to-you-but-not-to-me problems with that function under such circumstances? Thanks for any clue Jacques Paris e-mail [EMAIL PROTECTED] MapBasic-MapInfo support http://www.paris-pc-gis.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: 8391 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 8399
