Thanks for all the replies (and even a phone call). There were some good sites for reference provided:
http://www.efg2.com/Lab/Graphics/PolygonArea.htm http://www.pms.informatik.uni-muenchen.de/lehre/compgeometry/Gosper/TOC.html I ended up using the simplest algorythm based on the following: Area=(Sum(yi-yn+1)*(xn+xn+1))/2 Further research identified it as the algorythm that is used for planimeters, i think it is called the gauss-green formula. I tried it out on a few polygons of known size and it actually worked, and gave comparable results to mapinfo. As the application will only ever deal with simple polygons, I will go with it at present. For anyone that is interested in the code, I used the following VB function, which returns an area value after passing two arrays of x and y coordinates to it. Private Function fCalcArea(X, Y) As Single 'X and Y are arrays of x and y coordinates Dim i As Integer Dim rtn As Single fCalcArea = -999 rtn = 0 For i = 1 To UBound(X) - 1 rtn = rtn + (Y(i) - Y(i + 1)) * (X(i) + X(i + 1)) Next i rtn = rtn / 2 fCalcArea = rtn End Function Thanx u all Robert. ---------------------------- Robert Crossley Robert Crossley and Associates 9 Short Street NEW BRIGHTON NSW Australia 2384 P: 61-2-66801309 M:0419718642 ---------------------------- _______________________________________________________________________ List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, send e-mail to [EMAIL PROTECTED] and put "unsubscribe MapInfo-L" in the message body.
