Hello Mike, I believe MapInfo uses an odd/even rule. Here's a link to a reasonable explanation:
http://www.daimi.au.dk/~beta/doc/bifrost-ref/bifrost-ref-12.html The annoying thing with MapInfo data (whether TAB or MIF/MID) is that the polygons can be in any order. Polygon 1 might be a "hole". I would suggest you normalise your polygons before export to MID/MIF so that your on-going processing can make assumptions. I always normalise so that the first polygon is the "positive" and subsequent polygons are the holes. If you need more than one disjoint positive polygon, use multiple records. This simple normal form doesn't handle positive areas within holes within positives etc., but these can often be avoided. Regards, Warren Vick Europa Technologies Ltd. http://www.europa-tech.com -----Original Message----- From: Mike Kennett [mailto:[EMAIL PROTECTED]] Sent: Tuesday, January 07, 2003 5:06 PM To: '[EMAIL PROTECTED]' Subject: MI-L MIF format Hi there I'm using a cellular radio planning tool which outputs MIF files, which I need to manipulate outside MapInfo. I have a MIF/MID format document from the MapInfo website but it doesn't tell me how MapInfo knows whether or not to fill overlapping regions. Can anyone help? For example, if region A completely encloses region B then region B is unfilled. But if region C intersects (but does not completely enclose) region D then region C and region D are both filled. If I then add a region E which completely encloses both C and D then C and D are holes, except for the C/D overlap which is filled. It seems like changing the order of regions in the MIF has no effect. I've included a short MIF below to illustrate the problem. This can be imported into MapInfo and viewed. Change the display settings in Layer Control to see which regions are filled. What I'd really like is a set of rules and/or an algorithm which would determine which regions or parts of regions are filled. Many thanks -Mike Kennett Horsham, UK ~~~~~~~~~ Version 300 Charset "WindowsLatin1" Delimiter "," CoordSys Earth Projection 8, 79, "m", -2, 49, 0.9996012717, 400000, -100000 Bounds (-7845061.1011, -15524202.1641) (8645061.1011, 4470074.53373) Columns 1 Sector_Name Char(32) Data Region 5 5 200000 400000 200000 410000 210000 410000 210000 400000 200000 400000 5 203000 403000 203000 407000 207000 407000 207000 403000 203000 403000 5 202000 402000 202000 404000 204000 404000 204000 402000 202000 402000 5 209000 403000 209000 407000 213000 407000 213000 403000 209000 403000 5 203100 403100 203100 403500 203500 403500 203500 403100 203100 403100 Pen (1,2,0) Brush (2,16777215,16777215) Center 201500 405000 ~~~~~~~~~~~~~ --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 4793 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 4795
