Better title: Strains from CAT scans
This is the first time I've forwarded a
letter from one mailing list to another,
so I hope it's ethical and proper. My
access to structural geology for some
years has been only this list, where
I've not seen mention of medical imaging
techniques.
Though it's difficult to imagine they
haven't been used, the image of a fossil
(of fixed shape) and the
three-dimensional image of its deformed
species should allow a strain tensor at
its center to easily be approximated, to
within a multiplicative constant. (Only
five pairs, I believe, are needed to
calculate the projective transformation
between two sprays of points.) Three
sections, of course, should provide the
same information.
Because traffic here is slow, I thought
this might provide some interest. (J, by
the way, is a dialect of the APL
programming language. The responses
sought from the J programmers are
lesser-known algorithms from image
analysis, a subject well-studied by
many.)
Bruce Bathurst
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