# ALPACA module doesn't correctly register models of different size

**URL:** <https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208>\
**Category:** Support\
**Tags:** slicermorph\
**Created:** [August 28, 2020, 3:31am UTC](https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208 "2020-08-28T03:31:44Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![Dave\_Matthews](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/dave_matthews/32/7731_2.png) [@Dave\_Matthews](https://discourse.slicer.org/u/Dave_Matthews)\
**Post date:** [August 28, 2020, 3:31am UTC](https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208/1 "2020-08-28T03:31:44Z")

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I’ve segmented out the premaxilla of several guppies that I CT scanned. I place landmarks on one of the models and am trying to use ALPACA to transfer these landmarks to other models. This works well when I use two models that are very similar, but does not work to transfer landmarks between males and females (females are about twice as big as males).  
I have tried changing the alpha and beta values but this doesn’t fix the problem.

I’m wondering if ALPACA is able to deal with similar structures that are different sizes? Does either registration step account for size or do they only account for position and local shape change?

Thanks for any help!

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**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:** [August 28, 2020, 3:35am UTC](https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208/2 "2020-08-28T03:35:51Z")

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@Dave_Matthews @smrolfe and @agporto are working on that. It should be fixed in the next couple days…

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**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:** [August 28, 2020, 3:37am UTC](https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208/3 "2020-08-28T03:37:24Z")

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We’re just testing now, and will be updated shortly!

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**Author:** ![Dave\_Matthews](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/dave_matthews/32/7731_2.png) [@Dave\_Matthews](https://discourse.slicer.org/u/Dave_Matthews)\
**Post date:** [August 28, 2020, 4:56am UTC](https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208/4 "2020-08-28T04:56:46Z")

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Thanks very much for the quick reply!

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**Author:** ![Chuan](https://avatars.discourse-cdn.com/v4/letter/c/4da419/32.png) [@Chuan](https://discourse.slicer.org/u/Chuan)\
**Post date:** [November 16, 2023, 8:38am UTC](https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208/5 "2023-11-16T08:38:54Z")

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Hi Smrolfe,

Recently I also meet the similar problem, do you have an answer now?

Best regards,  
Chuan

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**Author:** ![Chuan](https://avatars.discourse-cdn.com/v4/letter/c/4da419/32.png) [@Chuan](https://discourse.slicer.org/u/Chuan)\
**Post date:** [November 16, 2023, 8:40am UTC](https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208/6 "2023-11-16T08:40:40Z")

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Hi Muratmaga,

Do you have any suggestion now? Or is there any similar post about transfer landamrks in Slicer?

Best regards,  
Chuan

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**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:** [November 16, 2023, 3:50pm UTC](https://discourse.slicer.org/t/alpaca-module-doesnt-correctly-register-models-of-different-size/13208/7 "2023-11-16T15:50:45Z")

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That has been fixed sometime ago, and there is now a scaling option built-in (you can disable it by choosing skip scaling).

If it is still not working right for you, please share the two models and the LMs you want to transfer.