Calculate the area of a polygon and its boundary direction.
areapoly(poly)
matrix containing the x,y-coordinates of the vertices of the polygon boundary.
x,y
positive numeric, the area of the polygon.
integer, 1 if the polygon orientation is anticlockwise, -1 otherwise.
copy of the passed argument poly.
poly
Joseph O'Rourke, Computational Geometry in C (2nd Edition), Cambridge University Press, 2000 edition.
metre, risk.colors
metre
risk.colors