creating mirror reflection of one-side landmarks

[Christy Hipsley]

Dear Geomorphers,

I'm working with a 2D landmark data set of vertebrae in anterior view in which one side (right) has been landmarked, with 5 landmarks along the midplane axis for a total of 12 landmarks. 

I would like to generate a mirror reflection of the paired landmarks, and wonder if there is an easy way to do this in geomorph or another program. I naively tried multiplying the x coordinate dimensions *-1 and keeping y the same, but since the midplane x coordinates are not at 0 this obviously doesn't work.

Any advice or code would be greatly appreciated!

Thanks,

Christy

[Antigoni Kaliontzopoulou]

Hi Christy,

I do not know that there is any standard routine to do that, but it should be fairly easy to write one in R. I guess one would need to find the actual reflection plane through e.g. an RMA regression of the points of the midline, set that as x = 0 and then mirror the coordinates as you were doing.

Hope this helps

Antigoni

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Antigoni Kaliontzopoulou 

Assistant Researcher
CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos
University of Porto
Campus Agrário de Vairão, 4485-661 Vairão
PORTUGAL

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http://antigonik.wix.com/akaliontzopoulou
http://www.seh-herpetology.org/

[Javier Santos]

Hello Christy,

In Claude's book [Claude - Morphometrics With R - 2008] you can find some script on which to base yourself upon to make the mirror reflection.

You should be able to find the .pdf online.

Best wishes,

Javier Santos-Santos

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From: geomorph-...@googlegroups.com <geomorph-...@googlegroups.com> on behalf of Antigoni Kaliontzopoulou <anti...@cibio.up.pt>
Sent: Friday, August 24, 2018 8:55:46 AM
To: geomorph-...@googlegroups.com
Subject: Re: [geomorph-r-package] creating mirror reflection of one-side landmarks

 

To view this discussion on the web, visit https://groups.google.com/d/msgid/geomorph-r-package/3c284766-81bf-d270-2501-44e23484d058%40cibio.up.pt.