-------- Original Message --------
Subject: Outlines in tpsDig
Date: Thu, 23 Oct 2008 11:39:20 -0700 (PDT)
From: Sarah Degroot <[EMAIL PROTECTED]>
To: <[email protected]>
I am trying to make my tps files multitask-- I have black & white images
and want to digitize outlines such that I can use the points in both EFA
and a sliding landmark analysis. However, some of the specimens are
fairly complex, such that I need at least 220 points to capture the
outline adequately. I don't want to place 220 points by hand,
especially since my preliminary analysis involves over 570 specimens. I
tried drawing a curve with tpsdig, but that took 28 points (minimally),
and it captured the outline poorly (even though I resampled the curve
with more points). I'm also not eager to place even 28 points on each
of 570+ specimens--there has to be a faster way.
It seems the easiest thing to do would be to use the outline tool in
tpsdig, but this tool appears to be inconsistent about where it places
the starting point. I click just to the right of where I want the
starting point, but when I look at the tps file, the starting point is
clearly somewhere else around the outline, and usually nowhere near
where I clicked. This is the case for both tpsdig 2.09 and 1.40 (1.40
has given me a few other outline anomalies, too, such as negative
coordinates).
I need the starting position of the x-y coordinates for the outline to
be in the same place on all specimens because (1) I am not correcting
for starting position in EFA because I do not want the outline rotated
(they are all oriented the same way, but the long axis is not
necessarily the same), and (2) I want one fixed "landmark" as a
reference point for the sliding landmark analysis.
I'd like something similar to Perez et al.'s (2006; J. Anat. 208:
769-784) placement of semilandmarks around molars, although I'm not
quite sure how they did it. I can't imagine they placed all 80 points
by hand (p. 772).
Suggestions are appreciated.
Sarah
sarah.degroot at cgu.edu
Graduate Student
Rancho Santa Ana Botanic Garden / Claremont Graduate University
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