morphmet
Mon, 16 Nov 2009 14:16:31 -0800
-------- Original Message -------- Subject: RE: centroid size and different distances from the object Date: Mon, 16 Nov 2009 19:03:50 GMT From: Cabo-Perez, Luis <lc...@mercyhurst.edu> To: morphmet@morphometrics.org <morphmet@morphometrics.org> References: <4b016462.2010...@morphometrics.org> Tina,If you are sure of the length of the skulls in the old photos you can photoshop a scale in them. Just draw a line between the two landmarks defining the length, rotate it until it is completely horizontal (use the gridlines), and free transform it reducing the length (x) by 100/length (for example, if you have a 5 cm length, and you want the scale to be 1 cm, just reduce it to 100/5=20%). Then take your new photos with an scale. You will have to digitize the old photos again, adding the two points for the scale at the end (if you are using tps), and they may be some noise added in the new photos depending on the placement of the scale (if you think that may be a factor, just measure them and rather photoshop the scale in the same way that you did with the old ones), but I think it is worth it if you can compare your old sample with the new one.
You may also be able to simply digitizing the old photos again, measuring the two length landmarks twice, the second time as the final two scale landmarks, and then enter in each specimen the measured length as the "scale length" in the scale dialog, but I never tried that (always had the same scale, so don't know if that would be a problem when putting all the files together in a single file)
Luis ________________________________ Luis Cabo Department of Applied Forensic Sciences, Mercyhurst Archaeological Institute, lc...@mercyhurst.edu -------- Original Message -------- Subject: centroid size and different distances from the object Date: Mon, 16 Nov 2009 11:06:26 GMT From: tina klenovsek <tina_klenov...@yahoo.com> To: morphmet@morphometrics.org Please help! I have a collection of photos of mammal skulls that I took for morphometric analysis. But now I got new specimens of the same species that I would like to include into the already mentioned analysis. The problem is, I can't photograph new specimens under the exact conditions I photographed the first. Especially the DISTANCE of the camera from the skull is the problem. I can't photo the old again because they have been borrowed from many different museums and have already been returned. What shall I do? I need to calculate CENTROID SIZE for all specimens. Is this possible? I also don't have any scale on the old photos, but I know the exact length and width of every skull, is this enough? Please help me. I don' want all my old photos to go to waste. Thank you in advance! Tina -- 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