-------- Original Message --------
Subject: Re: right/left looking photos for human face shape
Date: Thu, 3 Nov 2011 09:52:07 -0400
From: Dean Adams <dcad...@iastate.edu>
To: morphmet@morphometrics.org <morphmet@morphometrics.org>
Mark,
I played around with this issue (parallax) years ago, and agree that the
orthogonal projection approach off PC1 by Gharaibeh is often a useful
solution. As mentioned by Andrea, regression residuals may also do the
trick. However, I found that the best solution is often data-dependent.
Thus I recommend exploring both possibilities with your data to
determine whether the lack of standardization of face position generates
a predictable pattern (see Fig 1 in Gharaibeh).
That said, I would caution against eliminating the uniform component
from the analysis. While this may improve the fit in some circumstances,
it will also of course eliminate all uniform shape variation, which can
be considerable in some datasets. Additionally, it turns out that the
shape distortions generated by non-standardized specimens in front of
the digitizing plane are often highly non-linear, such that most of this
variation will not be embedded in the uniform shape components. In which
case, eliminating the uniform component will remove actual uniform shape
variation, but not variation due to lack of positional standardization.
Dean
--
Dr. Dean C. Adams
Associate Professor
Department of Ecology, Evolution, and Organismal Biology
Department of Statistics
Iowa State University
Ames, Iowa
50011
www.public.iastate.edu/~dcadams/
phone: 515-294-3834
On 11/2/2011 5:17 PM, morphmet wrote:
-------- Original Message --------
Subject: Re: right/left looking photos for human face shape
Date: Wed, 2 Nov 2011 06:14:49 -0400
From: andrea cardini<alcard...@interfree.it>
To: morphmet@morphometrics.org
Dear Mark,
years ago, on a small dataset with the same individual photographed under
two different angles, I managed to control for the angle by simply using
residuals of a regression of shape onto the angle. By excluding the uniform
component of variation from the regression, the accuracy of the model was
improved. Likely a large amount of differences between the two pictures
were approximately uniform.
Possibly you may be able to do something similar, validate the regression
model on subjects for which you have two pictures and then apply it to
those for which you have only one picture.
If you manage to get a pdf of the chapter mentioned by Dennis, I'd greatly
appreciate if you could send me a copy. Thanks in advance.
Cheers
Andrea
At 14:33 01/11/2011 -0400, you wrote:
-------- Original Message --------
Subject: right/left looking photos for human face shape
Date: Tue, 1 Nov 2011 00:10:00 +0000
From: Mark Belk<mark_b...@byu.edu>
To: morphmet_modera...@morphometrics.org
<morphmet_modera...@morphometrics.org>
Does anyone have a suggestion for how to correct for right/left lookers
in human face shape. A colleague has a series of historical photos of
people with known pedigrees, but many of the subjects are turned a few
degrees to the right or left. Any suggestions on how to adjust for this
rotation in the landmarks?
Thanks,
Mark
Mark C. Belk
Professor of Biology
Editor, /Western North American Naturalist/
Brigham Young University
801-422-4154
Dr. Andrea Cardini
Researcher in Animal Biology
Dipartimento di Biologia, Universitá di Modena e Reggio Emilia, via Campi
213, 41100, Modena, Italy
tel: 0039 059 2055017 ; fax: 0039 059 2055548
Honorary Fellow
Functional Morphology and Evolution Unit, Hull York Medical School
University of Hull, Cottingham Road, Hull, HU6 7RX, UK
University of York, Heslington, York YO10 5DD, UK
Adjunct Associate Professor
Centre for Forensic Science , The University of Western Australia
35 Stirling Highway, Crawley WA 6009, Australia
E-mail address: alcard...@interfree.it, andrea.card...@unimore.it,
andrea.card...@hyms.ac.uk, andrea.card...@uwa.edu.au
Webpage: http://sites.google.com/site/hymsfme/drandreacardini
Datasets:
http://ads.ahds.ac.uk/catalogue/archive/cerco_lt_2007/overview.cfm#metadata
Editorial board for:
Zoomorphology:
http://www.springer.com/life+sciences/animal+sciences/journal/435
Journal of Zoological Systematics and Evolutionary Research:
http://www.wiley.com/bw/journal.asp?ref=0947-5745&site=1
Hystrix, the Italian Journal of Mammalogy:
http://www.italian-journal-of-mammalogy.it/
