RE: Semilandmarks

Wed, 21 Nov 2012 13:14:10 -0800


----- Forwarded message from "F. James Rohlf" -----

Date: Tue, 20 Nov 2012 14:22:23 -0500
From: "F. James Rohlf"
Reply-To: [email protected]
Subject: RE: Semilandmarks
To: [email protected]

The answer to this question is, perhaps, not fully resolved. Minimizing bending energy adjusts semilandmarks so the implied shape change is as smooth as possible. Fred Bookstein advocates this. I think minimizing Procrustes distance is more consistent with the overall GPA superimposition that minimizes Procrustes distances. Usually the result look pretty similar – although of course not exactly the same. I think the plot of the superimposed specimens after a GPA looks much more like what one would intuitively expect if one minimizes Procrustes distances (the among specimens scatter at each semilandmark are mostly perpendicular to the outline). That is not true when bending energy is minimized.  However, I don’t think anyone has done an extensive simulation to investigate the statistical properties of either method.

 

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F. James Rohlf, John S. Toll Professor, Stony Brook University

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From: [email protected] [mailto:[email protected]]
Sent: Sunday, November 18, 2012 11:49 PM
To: [email protected]
Subject: Semilandmarks

 


----- Forwarded message from Kalpana Das -----

Date: Sun, 18 Nov 2012 09:15:34 -0500
From: Kalpana Das
Reply-To: Kalpana Das
Subject: Semilandmarks
To: [email protected]

Hey all,
I am currently doing shape analysis of frog's snout shape using sliding semilandmarks method as there are very few landmarks.
As there are two different ways to slide semilandmarks ,I am a little confused which one to use.
I used both of them and they are generating different results.I need some insights into this problem.
It would be equally great if some of you have good literature on this topic and willing to share with me.

Thank you

Best,
Kalpana

--
Kalpana
Center for Ecological Sciences
Indian Institute of Science
Bangalore,India
Email- [email protected]
Mobile no-9620313751/8010255368

"Not everything that counts can be counted, and not everything that can be counted counts."




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