Dear Lawrence,

You can use geomorph's gpagen function for sliding semilandmarks during
Procrustes superimposition, by minimising bending energy or by minimising
Procrustes distance.

I would say that it is better to sample the curve in IDAV Landmark
Editorwith many semilandmarks, in order to avoid as many issues of
smoothing the curve of interest. Also, if you link two or more curves
together in IDAV Landmark Editor, then first use digit.curves function in
geomorph to resample the semilandmarks of those curves (since IDAV Landmark
Editor does not consider two curves sharing 1 landmark as linked and places
equally distant semis on each curve separately).

Details of geomorph below in my signature, including the extensive help
guide.

Emma

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Emma Sherratt, PhD.


Postdoctoral Researcher in the Keogh Lab
<http://biology-assets.anu.edu.au/hosted_sites/Scott/>
Division of Evolution, Ecology & Genetics
Research School of Biology
116 Daley Road
The Australian National University
Acton, ACT  2601
AUSTRALIA

email: [email protected]
office tel: +61 2612 54943
mob: +61 4234 19966
Twitter: @DrEmSherratt <https://twitter.com/DrEmSherratt>
co-author of geomorph R package: Software website
<http://geomorphr.github.io/geomorph/> | CRAN website
<https://cran.r-project.org/web/packages/geomorph/> | googlegroups
<https://groups.google.com/d/forum/geomorph-r-package>

Caecilians are legless amphibians...

*                      __
    (\   .-.   .-.   /_")
     \\_//^\\_//^\\_//
      `"`   `"`   `"`*

learn more about them here: www.emmasherratt.com/caecilians




On 7 December 2016 at 05:21, Lawrence Fatica <[email protected]>
wrote:

> Hi all,
>
> I am working on a project examining shape variation in the pelvis. I used
> IDAV Landmark to place four curves of five semilandmarks each (as well as
> several fixed landmarks) along the major contours of the pelvis. I plan on
> doing the analysis in R, but I am unsure what my options are for
> semilandmarks sliding along curves. I am particularly concerned that the
> semilandmarks will slide along their tangents and off the bone when using
> sliding protocols that do not include the 3D mesh itself.
>
> Is this something I should be worried about? Has anyone else had success
> using sliding semilandmarks along curves?
>
>
> Thanks in advance for any insight,
>
> Lawrence
>
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