DanA> Thanks for the links. The angle used to normalize what I call the map-of-France is exactly what I proposed: Divide the unnormalized set by 2 + exp(2pi*i/6). What I asked is whether there are other ways of doing it as well. I am extremely familiar with the definition of Hausdorff measure (and dimension). What I don't know is how to compute it for even slightly complicated actual examples like the map-of-France. --Dan Dan, look at http://www.mathcurve.com/fractals/gosper/gosper-pavage3.gif Each subFrance shares 1/6th of its boundary with each neighbor, leaving 6/2 = 3 to comprise the outer boundary, which must be sqrt 7 times bigger than a subFrance boundary by area consideration. So scaling the boundary stuff by sqrt 7 gets you three times as much. This was in the original Gardner article. Or is this the way you were doing it? --rwg Also I forgot to mention that the rotating gridflo<http://gosper.org/gridrot.gif>is slightly different from the first one I mentioned <http://gosper.org/gridflo.png>, but they both mess with your eyes the same way. Actually, it's probably a simple optical effect rather than a hairy perceptual illusion. We should be able to simulate astigmatism with a simple anisotropic blurring filter.