On a technical point, one does not transform landmarks into
semilandmarks. They either are landmarks or semilandmarks. The fact that
they are semilandmarks is sometimes ignored, and they are treated as
landmarks if the ambiguity in positioning on one direction is deemed
sufficiently small or they can be allowed to slide to take out
variability in that direction. So, semilandmarks are semilandmarks, but
they can be "transformed" into sliding landmarks.
-ds
On 5/6/15 7:29 AM, Nico Posnien wrote:
Dear all,
I have a question concerning the analysis of landmark and semilandmark
data in fly heads. So far I placed landmarks on 2D images. Some of these
actually represent semilandmarks. I used tps Util ("Make Sliders File";
see attched picture) to generate a sliders file. In the attached
picture, 1 and 8 are landmarks and 2-7 in between them are supposed to
be semilandmarks.
My first question is: Is this the right way to transform landmarks into
semilandmarks?
My second question is: What is the best (most accepted,
straight-forward) way to further analyze this data? I am mainly
interested in shape differences between different groups (2 species +
hybrids, males and females). Which programs should be used? I saw that
geomorph can handle this kind of data. Any UI software? Are there any
suggestions for good tutorials?
Thanks a lot for any recommendation and help!
Cheers,
Nico
--
Nico Posnien
Georg-August-University Göttingen
Johann-Friedrich-Blumenbach Institute for Zoology and Anthropology
Department of Developmental Biology
Ernst-Caspari-Haus (GZMB)
Justus-von-Liebig-Weg 11
37077 Göttingen
Germany
Phone: +49 (0) 55139 20817
E-mail: [email protected]
web: http://www.evolution.uni-goettingen.de/posnienlab/index.html
web: http://www.uni-goettingen.de/en/44993.html
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