HI Thomas, You can use morphologika to do this, but there is an extra step involved: First do the superimposition of the whole set of landmarks. Then you extract the superimposed coordinates from the output window and make a new input file. Run the new file and turn off the unwanted points. Then tick the 'no scale', 'no rotation' and 'no translation' boxes, and do the 'dummy Procrustes'. You will then be able to do the PCA and examine the variation in the way that you desire.
Regards, Nick Milne [EMAIL PROTECTED] -----Original Message----- From: morphmet [mailto:[EMAIL PROTECTED] Sent: 22 November 2006 2:47 AM To: [email protected] Subject: Working with a subset of Landmarks I am currently working with a set of 3D landmarks to analyze the shape of joint surface areas on bones. I want to be able to use landmarks to describe the shape of the bone, and thereby the orientation of the joint surfaces, when I conduct the Procrustes superimposition. After superimposition, I would like to be able to ignore the landmarks that that do not describe the joint surfaces. In this way, differences in joint facet orientation will be part of the shape differences, but I no longer want to consider shape differences for the rest of the bone. My problem is in getting a program to display shapes, with deformation grids, without having to conduct a new Procrustes analysis. I've been using Morphologika for this project, but Procrustes superimposition is a necessary step before PCA and Display grids are available. Re-doing the superimposition at this point would lose the orientation information. I can certainly do the PCA analysis independent of this program, but I want to be able to use the display options. Does anyone know of a program that would allow me to do the deformation grid display of 3D landmarks without having to go through the superimposition steps first? Once again, thanks for your help. *//**/Thomas M. Greiner, Ph.D./* Assistant Professor of Anatomy University of Wisconsin - La Crosse Department of Health Professions 4054 Health Science Center 1725 State Street La Crosse, WI 54601 Phone: (608) 785-8476 Email: [EMAIL PROTECTED] -- Replies will be sent to the list. For more information visit http://www.morphometrics.org -- Replies will be sent to the list. For more information visit http://www.morphometrics.org
