-------- Original Message --------
Subject: Re: How to determine landmark density in patches and curves
for a specific area?
Date: Wed, 2 Nov 2011 06:59:56 -0400
From: andrea cardini <[email protected]>
To: [email protected]
Dear Helmi,
my guess is that the density depends on the complexity of the structure and
what you need to do. One could test the sensitivity of results to this
parameter (e.g., Sanfilippo P., Cardini A., Sigal I.A., Ruddle J., Chua B.,
Hewitt A., Mackey D.A, 2010 - Geometric Morphometric Assessment of the
Optic Cup in Glaucoma. Experimental Eye Research, 91: 405-414 - preprint
pdf in my webpage).
I would also carefully consider what those landmarks mean in terms of your
scientific hypotheses:
Klingenberg, C. P. 2008. Novelty and homology-free morphometrics:
Whats in a name? Evolutionary Biology 35:186190.
Oxnard and O'Higgins, 2009, Biology certainly needs Morphometrics. Does
Morphometrics need Biology? Biological Theory 4 (1): 84-97.
Good luck.
Cheers
Andrea
At 13:43 28/10/2011 -0400, you wrote:
-------- Original Message --------
Subject: How to determine landmark density in patches and curves for a
specific area?
Date: Thu, 27 Oct 2011 06:25:23 -0400
From: hmi hmi <[email protected]>
To: morphomet morphometrics.org <[email protected]>
Dear morphometricians,
How do you determine the amount of landmarks needed for patches and
curves for a specific area? Does over-landmarking generate meaningful
results? Landmarking a surface very sparse would result in under
representation. Is there some sort of golden rule to follow?
I've used resample.exe to resample down a 100-90+ landmarks to 20 of the
orbital shape of human skulls. I notice that some skulls have
supra-orbital notch, some don't. The resampled results show a circular
shape without the notch, though in morphoJ I could see the vector arrows
around the region of the notch, though that is only found on the 7th PC
(around 2.5%).
Another example would be using a patch function in the IDAV landmark
software. Lets say I place a patch on the temporal bone. Since this
region is quite smooth I am not sure how dense I have to make the patch.
It would be useful if there is some sort of virtual 3D scale/ruler which
could wrap around the surface of the object as the density could be
referenced to scale. However I am not sure if that kind of software exists.
Thank you
Helmi Pritam
[email protected]
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: [email protected], [email protected],
[email protected], [email protected]
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/
