AutoCAD Map 3D General

Distinguished Contributor
Posts: 110
Registered: ‎10-03-2008
Message 1 of 2 (154 Views)

Calculation with complex polygons

154 Views, 1 Replies
03-20-2009 12:01 PM
I created a complex polygon (two unconnected squares as one entry) in my shape file, then I added a simple calculation to give me area in acres. But for the complex polygon it returns a negative number. Anyone know of any problem with complex polygons and area calculations?
Active Member
Posts: 10
Registered: ‎09-02-2004
Message 2 of 2 (154 Views)

Re: Calculation with complex polygons

06-08-2009 06:50 AM in reply to: cstringer80
I've had this problem for years with Map (currently using Map 2008), with both simple and complex polygons. I make closed polygons (property boundaries) with LWPOLYLINES, populate them with object data, then use MapPolylineToPolygon to convert them to mpolys. Map randomly creates mpolys with negative areas; doesn't matter if the original lwpolyline was drafted clockwise or counterclockwise, has internal islands or not. The only workaround I've found is to open the negative-area mpolys with MPedit and rebalance. It's a real pain if I have several hundred mpolys in a file; I've had more than half of them with negative areas, and had to do the MPedit thing with every individual mpoly to get positive areas. About to switch to Map 2010 and hoping this problem is solved.

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