| To transform our geometric data to GRASS I am looking for an algorithm to
| find a point for an area polygon which is definitely inside the polygon.
| It's a kind of point-in-polygon question, but I have the polygon not the
| point.
I have an algorithm, coded in Fortran, that finds such a point. First it
calculates a "centroid" from the mean of the x and y values. If that point
is found to be outside the polygon, it locates the closest line segment to
the "centroid". From there, a sequence of points are tested along the
perpendicular to that line segment, until an inside point is found. If you
are interested, I will be happy to e-mail you the source code.
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Peter Strong
National Park Service
@cerl.cecer.army.mil:nps\!peter