This command rebuilds a triangulation surface within a
perimeter. The perimeter is selected using a closed polyline. The
command embeds the perimeter polyline into the triangualtion using
the elevations of the triangulation. Then the triangles within the
perimeter are removed. Next the area within this area is
retriangulated using the elevations around the perimeter.
One application of this command is to discard a problem area of
the triangulation and rebuild this area using the good elevations
around the perimeter of this area.