-------- Original Message -------- Subject: Re: Image rotation data loss Date: Sun, 29 Jun 2014 03:38:32 -0400 From: Dennis E. Slice <dsl...@morphometrics.org> To: morphmet@morphometrics.org First guess would be your landmarks are out of order on one or more specimens. You can check this by creating a set of links in tpsUtil and plotting the data showing the links. And/or, in tps, plot the data showing points and vectors. -ds On 6/29/14, 12:27 AM, morphmet_modera...@morphometrics.org wrote:
Hello all, I'm trying to digitize photos in tpsDig for a geometric morphometrics study on Notropis fishes. In order to test for digitization error I've copied the first fish photo I took 10 times and digitized each one onto the same TPS file (made in tpsUtil). I then performed a relative warps analysis in tpsRelw and performed a Procruste's superimposition in R (package geomorph) to glance and see if any landmarks varied significantly. My results show very drastic variation in landmark placement, with dots all over the place in the GPA plot. I know my landmark placement isn't that bad, so I think it might have something to do with data loss. When I photographed the specimen the fish was flipped, so I had to rotate and flip it to turn it rightside up before digitization. Is it possible that rotating the photo resulted in data loss and therefore digitization error? The TPS file had the landmark coordinates for each specimen pretty close together (about normal landmark placement error), but the GPA and relative warps plots showed drastic variance. I've attached the GPA plot to show what I mean. The landmarks are supposed to go around the entire fish. Also let me know if you have any other ideas for why there might be crazy variance. Best, Connor connorfre...@utexas.edu <mailto:connorfre...@utexas.edu> ----- End forwarded message ----- ----- End forwarded message ----- ----- End forwarded message -----
