# Reflect markups (landmarks)

**URL:** <https://discourse.slicer.org/t/reflect-markups-landmarks/20301>\
**Category:** Support\
**Tags:** markups-fiducials, slicermorph\
**Created:** [October 22, 2021, 2:29pm UTC](https://discourse.slicer.org/t/reflect-markups-landmarks/20301 "2021-10-22T14:29:56Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ale](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ale/32/67086_2.png) [@Ale](https://discourse.slicer.org/u/Ale)\
**Post date:** [October 22, 2021, 2:29pm UTC](https://discourse.slicer.org/t/reflect-markups-landmarks/20301/1 "2021-10-22T14:29:56Z")

</div>

Dear list, I’m placing markups (landmarks) to carry out a geometric morphometric analysis in some mammals skulls. I have some cases where one of the zygomatic archs is missing (screen capture below). Is there a way to reflect one side markups based on a defined plane to estimate landmarks of the missing structure (in this case the right zygomatic arch).  
Kind regards,  
Alej

![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/8/c/8cdc462baa87494b37aade3ed2f2eaf27c71c077.jpeg)

---

<div class="post-metadata">

**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [October 22, 2021, 3:08pm UTC](https://discourse.slicer.org/t/reflect-markups-landmarks/20301/2 "2021-10-22T15:08:30Z")

</div>

Currently there is no automated (or UI driven) way of doing it. You will have to define the symmetry plane (Markups-\>Plane tool) and then the position of the LM can be reflected using that particular plane.  
@smrolfe

---

<div class="post-metadata">

**Author:** ![smrolfe](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/smrolfe/32/3659_2.png) [@smrolfe](https://discourse.slicer.org/u/smrolfe)\
**Post date:** [October 22, 2021, 3:20pm UTC](https://discourse.slicer.org/t/reflect-markups-landmarks/20301/3 "2021-10-22T15:20:44Z")

</div>

I wrote a function that does this in Python [here](https://github.com/SlicerMorph/SlicerMorph/blob/7cc50a5042a12692fb0624875f204a7c8ede64ad/PseudoLMGenerator/PseudoLMGenerator.py#L710). It does a few extra things (merges points that are very close to the symmetry plane, creates a left, right and merged landmark set) so it would need to be altered a little bit. The plane needs to be defined or calculated before using this function, as @muratmaga noted.