How can I make a plane from 3 midsagittal fiducials?


I’m trying to place fiducials and open curves on a juvenile skull’s fontanelle (the unfused place where there’s no bone), so it’s landmarking an open/negative space not on the actual model. To do that I want to create a mid-sagittal slice that’s based on 3 fiducials that I make along the midline of the skull.

So I’m wondering: How do I make a slice/cut-plane based on my own fiducials?

Does anyone know how to do that?

Create a blank MarkupsPlane node and copy and paste those three points from the MarkupFiducial into the Plane one (right click on the Control Points table)


You might also find ACPC Transform module useful, which can reorient an image to make the midsagittal plane exactly aligned with the sagittal view.

Short demo/tutorial video:


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Thank you so much for the quick reply, I’m checking with my supervisor to see if this is what she had in mind but it looked good when I tried it out.

Another quick question, on my adult skulls I resample my open-curves landmarks to the model surface so they’re evenly spaced. Since I’m moving points into the open space over the fontanelle to measure that curve I can’t resample (because they want to jump to the bone surface). Because they won’t be evenly spaced will that mess up my final comparison between adults and juveniles?

Thank you!

You can resample without snapping to surface.

If you compare curves (not control point positions) then it might not matter if control points are spaced equally.

I don’t know if it helps you, but in recent Slicer Preview Release you can choose not to snap points to visible surface when you are moving control points in a 3D view (initial placement is still done on the surface, but you can simply skip the fontanelle and then later insert points along the curve using Ctrl + Left-click).

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I forgot you could do that, thank you!

And I didn’t know about the shortcut for adding points that’s going to be really helpful.