On Tue, 2004-07-06 at 08:41, [EMAIL PROTECTED] wrote: > Hi, > > I too am just beginning, and have a large high rez image with many > skulls on it. I used Adobe Photoshop to cut out each image and save > them in separate files. I am now reading up on whether landmark > analysis requires that each file size (ie dimensions, and given that > each of my images is exactly a 1:1 ratio) be the same (ie whether the > landmarks refer to a reference point that is not part of the study > indiviudal such as a corner).
Not sure quite what to make of this question, so I will answer in general terms. The machinery of landmark-based morphometrics, such as Generalized Procrustes Analysis (GPA), does not require that the raw data be scaled identically. There is a step that factors out scale differences regardless of where they come from. If you wish to use physical size in your analysis, though, the data, i.e., coordinates, must be recorded to the same scale (e.g., mm) , but that scaling can be different for each picture - one might be 10 pixels/cm, another might be 7pix/cm, another 13pix/cm. Another factor to consider when recording multiple specimens in a single image is distortion. Ideally, you would want the rays forming the image to be travelling parallel to one another so there was no foreshortening due to the lens. The next best thing is to use the longest focal length available to record the desired image. Putting more than one specimen in an image, while economical with respect to time and storage, sacrifices resolution and could introduce distortion, especially for peripheral specimens. -dslice > > Kyle > __________________________________________________ > Dr Kyle Armstrong > JSPS Postdoctoral Fellow > Kyoto University Museum > Yoshida Honmachi, Sakyo-ku > Kyoto, Japan 606-8501 > TEL +81 75 753 7731 (shared) > FAX +81 75 753 3276 > email [EMAIL PROTECTED] > > $B%+%$%k!&%"!<%`%9%H%m%s%0!"(BPhD > $BF|K\3X=Q?66=2q309q?MFCJL8&5f0w(B > $B")(B606-8501 > $B5~ET;T:85~6h5HEDK\D.5~ETBg3XAm9gGnJ*4[(B > ___________________________________________________ > > > > ----- Original Message ----- > From: <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Thursday, July 01, 2004 10:12 PM > Subject: query > > > > Hello! > > I'm just starting with leave's morphometrics and I would really > > appreciate your advice on which programs to use to acquire data from > > scanned images in JPEG. In each file I have 25 leaves. I have been > using > > sigma scan to measure them, but I don't know how to get landmarks from > > many leaves in one image from this program. And of course later I'll > > need advice on how to analyzed data. > > > > Thank you in advance > > > > Lic. Cintia P. Souto > > Lab. Ecotono > > Univ. Nac.del Comahue > > Centro Regional Bariloche > > Quintral 1250 > > (8400) Bariloche > > R=EDo Negro > > Argentina > > Tel. ++54 2944 428505 int. 508 > > > > == > > Replies will be sent to list. > > For more information see > http://life.bio.sunysb.edu/morph/morphmet.html. > > > == > Replies will be sent to list. > For more information see http://life.bio.sunysb.edu/morph/morphmet.html. -- Dennis E. Slice, Ph.D. Department of Biomedical Engineering Division of Radiologic Sciences Wake Forest University School of Medicine Winston-Salem, North Carolina, USA 27157-1022 Phone: 336-716-5384 Fax: 336-716-5491 == Replies will be sent to list. For more information see http://life.bio.sunysb.edu/morph/morphmet.html.
