Brendan,
I see two ways of doing this in MapInfo without writting any MapBasic code.
1. Convex Hull will put a "rubberband" around your points and convert this "rubberband" into a region.
"The resulting region object(s) are based on the nodes from the input object. The Convex Hull
operation can be thought of as an operator that places a rubber band around all of the points. It
consists of a minimal set of points such that all other points lie on or inside the polygon. Since the
polygon is convex, no interior angles are greater than 180 degrees." from the MapInfo User Guide
2. Voronoi will convert each point to an area that will cover the area closer to this point than any other point.
"The Voronoi polygon is a partition of space into cells. Voronoi takes points and produces regions
(cells) as output where each cell contains exactly one point. Each cell is an area in which the
contained points are closer to the enclosed site than to any others. Use Voronoi to generate these
polygons from a designated set of points. It is useful for dividing areas of responsibilities for field
offices or possibly postal zones. It ultimately gives you the areas that are closest to your point of
interest." from the MapInfo User Guide
If you use the second, you will afterwards have to combine the objects with the same common attribute into one region.
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 Brendan Tagg
Sent: Thursday, July 06, 2006 7:38 AM
To: [email protected]
Subject: [MI-L] Points to Regions
Hi list,
I have bunches of points that need to be grouped together by an common attribute and then each group converted into seperate region. Does anybody know of a way to convert the "foot print" or a set of points make into a polygon / region. I have tried to query for one type and then buffer the objects (with the create "single object" option) but this creates a too course an object with excessive overlap because a circle shape is used.
EG for 1 particular group of points 'x' the output should be
From x x x /----x-- x- x\
x / x\_____
xx xxxxxxx Should become |xx xxxxxxx|
x xxx x xxx \x xxx x xxx-----/
x x x x \-x-------x-x-x----/
I am happy to write something in Mapbasic if I could figure out the algorithm (but a ready made tool would be better)
Hope this makes sense - any and all help is appreciated.
Brendan Tagg
Coles Myer Ltd.
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