# Landmarking Surface Model - File Formats

**URL:** <https://discourse.slicer.org/t/landmarking-surface-model-file-formats/15722>\
**Category:** Community\
**Tags:** slicermorph\
**Created:** [January 28, 2021, 6:43pm UTC](https://discourse.slicer.org/t/landmarking-surface-model-file-formats/15722 "2021-01-28T18:43:05Z")\
**Posts on this page:** 1\
**Showing post:** 4

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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:** [January 28, 2021, 7:20pm UTC](https://discourse.slicer.org/t/landmarking-surface-model-file-formats/15722/4 "2021-01-28T19:20:54Z")

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> [@EGlynne](#):
>
> I first have placed all my fiducial markups (fixed landmark). I then try to add an open curve markup to the mouth of the individual. I run into two questions here, first, when I go to resample the curve, if I constrain points to the surface of my model, it creates an odd shape.

Most people use Slicer for volumetric data. Meshes generated from volumetric scans have two surfaces (an internal and external surface). We implemented a projection option to make sure that we are finding the external surface to move the points on. This is irrelevant for surfaces that are derived from stereophotogrammetry. If you expand the Advanced section in Resample Curve option, you should be able to turn that off (or minimize it), and points will be on the surface like this:

![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/f/3/f323c428cdd3fe8c70ff28b357ec3bd2d10473d8.jpeg)

I suspect same problem is happening for the `PseudoLMGenerator` module, which also has a similarly named setting ‘Maximum projection factor’. Try setting it to zero (or low).

@smrolfe perhaps we might consider a toggle switch for surface vs volumetric meshes?

But more importantly, I think the scale of your input data is wrong. There has been long discussion why [STL is a poor format choice](https://discourse.slicer.org/t/beware-of-the-stl-file-format/7642/7) on the forum. As I measured, the skull is reported to be 0.1mm long. I suspect that’s not the case. If you can, try exporting the data from your original software in a format that will preserve the scale correctly, such as PLY.

> [@EGlynne](#):
>
> if I could use my prior fiducial points as the landmarks for the curve I want.

Yes, you can. Create blank curves node (red higlight), then copy and paste your existing anatomical fiducials (blue highlight).

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/7/e7f32138742d7d81230578c76ecb05447e35f28c.png)

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