3D semi-landmark analysis

[morphmet]

---------- Forwarded message ----------
From: *Erik Otarola-Castillo* <eotar...@iastate.edu
<mailto:eotar...@iastate.edu>>
Date: Wed, Dec 30, 2009 at 12:34 PM
Subject: Re: 3D semi-landmark analysis
To: morphmet@morphometrics.org <mailto:morphmet@morphometrics.org>


Francois,

Yes, if you are interested in quantifying and comparing
three-dimensional semi-landmarks, you would need to let the 3D
semilandmarks slide along their tangent directions (either along curves
or surfaces) during the GPA procedure to obtain correct estimates of
shape. The procedure is outlined in Gunz et al. 2005 (Semilandmarks in
three dimensions).

I believe Green and Bookstein’s Edgewarp software allows one to do this,
and it is freely available.

Dean Adams and I have recently developed an R routine for a general GPA
that allows superimposition of 2D or 3D landmark data. The landmarks can
represent locations of anatomical points, semilandmarks on curves, and
semilandmarks on surfaces. We are currently testing and packaging our
routine, and should have it available by February 1^st 2010.


Cheers,

Erik


On Thu, Dec 17, 2009 at 3:51 PM, morphmet
<morphmet_modera...@morphometrics.org
<mailto:morphmet_modera...@morphometrics.org>> wrote:



    -------- Original Message --------
    Subject: 3D semi-landmark analysis
    Date: Thu, 17 Dec 2009 17:16:02 GMT
    From: Francois Gould <fgou...@jhmi.edu <mailto:fgou...@jhmi.edu>>
    To: morphmet <morphmet@morphometrics.org
    <mailto:morphmet@morphometrics.org>>

    Dear list,
    I'm trying to figure out how to analyze 3D semilandmarks on a surface
    (specifically, a semi-landmark digitization of articular surfaces). 
If I
    understand things correctly, it is best to include a sliding algorithm
    in the Procrustes fitting stage (when all the semilandmark
    configurations are being translated, rotated and scaled). Am I correct
    in thinking this? And does anyone know of any software that 
incorporates
    sliding in a plane for 3D semilandmarks?
    Thank you.
    Yours,

    Francois Gould MSc
    Graduate Student
    Center for Functional anatomy and Evolution,
    Johns Hopkins, Baltimore




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--

_____________________________________________

Erik Otárola-Castillo
Ecology and Evolutionary Biology Graduate Program
253 Bessey Hall
Iowa State University
Ames, IA 50011-1050
Phone 631-796-7331
http://www.public.iastate.edu/~eotarola/homepage.html
______________________________________________




--

_____________________________________________

Erik Otárola-Castillo
Ecology and Evolutionary Biology Graduate Program
253 Bessey Hall
Iowa State University
Ames, IA 50011-1050
Phone 631-796-7331
http://www.public.iastate.edu/~eotarola/homepage.html
______________________________________________


--
Replies will be sent to the list.
For more information visit http://www.morphometrics.org