Fig. 8

Sections I-V driven by order 4 harmonic

Section VI driven by order 5 harmonic

Sections VII-XV driven by order 6 harmonic

Driving harmonic: the harmonic (Fourier coefficient) with the largest magnitude; it?s order marks the related closest polygon see in Heuristic Adequacy of Fourier Descriptors: Methodologic aspect and applications in Morphology. Pesce Delfino V., Lettini T., Vacca E. In: Fourier Descriptors and their Applications in Biology, P. E. Lestrel Ed., Cambridge Univ. Press, 1997.

A final question for the interested reader:

The considered Escher’s strip was a “morphological transformation series” but did M.C. Escher actually draw up a so subtle morphological transition at section VI (a discontinuity driven by order 5 harmonic placed between a previous continuous series driven by order 4 harmonic and a next one driven by order 6 harmonic) to be revealed by S.A.M. numerical description or was it a merely fortuitous finding?