-------- Original Message --------
Subject:        Re: PCA with VERY large number of landmarks?
Date:   Tue, 4 Oct 2011 21:11:26 -0400
From:   Carlos Fabian Morantes Ariza <[email protected]>
To:     [email protected]



Hi,

I think you should not use this huge amount of landmarks since you're going to lose sensitivity and you also can't ensure positional homology feasibility. I think you could find useful to treat your structure as a contour or (if they are 3D data) several soft patches. This will avoid the digitizing error. Another thing, you're not suppose to use more than N/2 landmarks (with N being sour sample size).

Hope this work



Carlos Fabian Morantes Ariza
Department of biology
Universidad Nacional de Colombia


2011/10/4 morphmet <[email protected] <mailto:[email protected]>>



   -------- Original Message --------
   Subject:     PCA with VERY large number of landmarks?
   Date:        Mon, 3 Oct 2011 21:48:03 -0400
   From:        Adam Douglas Yock <[email protected]>
   <mailto:[email protected]>
   To:  [email protected] <mailto:[email protected]>



   Hello,

   I am new to the field of morphometrics and have a (potentially very
   ignorant) question.

   I have images that contain a deformable body and a rigid body. The
   images are rigidly registered to align the rigid bodies. The
   deformable bodies are described by ~5,000 points which are matched
   across each image. I believe my data is then comprised of the 3D
   coordinates of the ~5,000 points of the deformable body depicted in
   each image.

   Can I treat these points as landmarks and perform a very
   high-dimensional (~15,000-D) PCA? Is there any "curse of
   dimensionality" with this method?

   I appreciate your help.
   Adam
   [email protected] <mailto:[email protected]>


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