# ALPACA module alignment help - shapes too different?

**URL:** <https://discourse.slicer.org/t/alpaca-module-alignment-help-shapes-too-different/15455>\
**Category:** Support\
**Tags:** registration\
**Created:** [January 11, 2021, 2:50pm UTC](https://discourse.slicer.org/t/alpaca-module-alignment-help-shapes-too-different/15455 "2021-01-11T14:50:07Z")\
**Posts on this page:** 4\
**Page:** 2

<div class="post-metadata">

**Author:** ![bobkallal](https://avatars.discourse-cdn.com/v4/letter/b/838e76/32.png) [@bobkallal](https://discourse.slicer.org/u/bobkallal)\
**Post date:** [January 20, 2021, 8:52pm UTC](https://discourse.slicer.org/t/alpaca-module-alignment-help-shapes-too-different/15455/21 "2021-01-20T20:52:38Z")

</div>

Thank you. You put more eloquently the fragments of the thoughts I’m having myself. Luckily my issue now involves a single sclerite that is self-contained and not touching another sclerite (that is, has no subdivisions like a skull), but it doesn’t seem like that will save me. I suppose even a 2D analysis using elliptical Fourier transform would need at least one homologous point too.

---

<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:** [January 20, 2021, 9:06pm UTC](https://discourse.slicer.org/t/alpaca-module-alignment-help-shapes-too-different/15455/22 "2021-01-20T21:06:49Z")

</div>

@bobkallal sorry don’t know the first thing about arthropods, so take everything with a good grain of salt.

I think you should experiment some and see how it works. It is part of the exploring the data. The point I am trying to make is be always aware of the issues and be critical of results. A combination of using your expert knowledge and some automated process might actually work. Perhaps at some point we might consider taking a set of landmarks as constrains on the mesh alignment in ALPACA (@agporto), but at this point it is not possible.

---

<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [January 20, 2021, 10:41pm UTC](https://discourse.slicer.org/t/alpaca-module-alignment-help-shapes-too-different/15455/23 "2021-01-20T22:41:30Z")

</div>

> [@muratmaga](#):
>
> we might consider taking a set of landmarks as constrains on the mesh alignment

Some of the SlicerSALT tools support this. For example, we rely on landmarks for shape analysis of heart valve leaflets (which all look like slightly bent somewhat circular disks).

---

<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:** [January 20, 2021, 10:53pm UTC](https://discourse.slicer.org/t/alpaca-module-alignment-help-shapes-too-different/15455/24 "2021-01-20T22:53:44Z")

</div>

> [@lassoan](#):
>
> Some of the SlicerSALT tools support this.

Thanks Andras. We might get some clues from there. @agporto @smrolfe

[Previous page](https://discourse.slicer.org/t/alpaca-module-alignment-help-shapes-too-different/15455.md?page=1)