Jim, do you really think that they "need to slide" or is it better to
consider that as a possibility depending on what the study aim is?
I think that sliding is useful sometimes but problematic other times (as
shown in my 2019 paper on spurious modularity/integration). Assuming
semilandmarks are important to the specific study question, it's an
option, it's not compulsory, it does not change the qualitative
difference between semilandmarks and landmarks (despite statements in
the literature that sliding makes semilandmarks 'homologous' - ref. in
my 'tautology' paper).
Best wishes
Andrea
On 28/12/2021 22:05, [email protected] wrote:
I have just uploaded new versions of tpsRelw and tpsRegr to the
sbmorphometrics.org server. The changes to tpsRelw fix a problem noticed by
Diego Astúa when using Boas coordinates and sliding semilandmarks at the same
time (the sliding operation had lost the original centroid size of each
specimen). I have now added a new option to tpsRelw to specify which size to
use. Because the position of semilandmarks along a curve is somewhat arbitrary
(which is why they need to slide) they affect the computed centroid size. The
new option allows one to use the initial centroid size before sliding anyway or
to do a more complex correction: size is first computed using just the
non-sliding landmarks and then after sliding the specimen is scaled so the
centroid size for the non-sliding landmarks is the same as before. Then the new
centroid size using all points is computed. Often seems to make only very small
differences but the option was added to allow for unusual situations.
A change was also added to make some of the other windows more visible on high
resolution monitors. I also changed the scaling for the windows displaying the
estimated shape using the thin-plate spline. It seems that by including size
one sometimes need to display more extreme deformations. The windows should now
scale better.
Thanks again to Diego Astúa for alerting me to the problem.
F. James Rohlf
Distinguished Professor, Emeritus and Research Professor
Depts: Anthropology and Ecology & Evolution
Stony Brook University
--
Dr. Andrea Cardini
Researcher, Dipartimento di Scienze Chimiche e Geologiche, Università di
Modena e Reggio Emilia, Via Campi, 103 - 41125 Modena - Italy
tel. 0039 059 4223140
Adjunct Associate Professor, Centre for Forensic Anthropology, The
University of Western Australia, 35 Stirling Highway, Crawley WA 6009,
Australia
E-mail address: [email protected], [email protected]
WEBPAGE: https://sites.google.com/view/alcardini2/
or https://tinyurl.com/andreacardini
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