Agreed. In addition, I think it’s important to note that, in the original
implementations of the sliding algorithm, semilandmarks were slid not along the
curve itself, but along tangents to the curve (= off the boundary outline). How
much distortion this induces is, of course, a function of how
I agree with Jim. However, this discussion does beg the question of what the
status of landmark, semilandmark, or indeed pixel brightness configurations
within multivariate spaces is? Very similar spaces have been used in the area
of theoretical morphology to conduct various sorts of
I can’t help you with PAST, but this reference will allow you to compute the
correct statistics for a standardized major axis (often erroneously called a
reduced major axis) regression.
Warton, D. I., et al., 2006, Bivariate line-fitting methods for allometry:
Biological Reviews, v. 81, no. 2,
