HI, Windows XP, Autocad2000 french. A 2D closed polyline with ~100 points give a surface of 542 sqm (m2). If we redraw this polyline directly on the first one, with approximatively the same contour but with 20 points, and if we move this surface beside the first one, the area of the second polyline becomes 900 sqm (m2) !!???. The perimeter is the same for the 2 lignes. Z=0 for all points. Thanks for help B.