Exporting outlines of segmented objects

I have set of previously segmented knee bones from MRI. In each slice, the segmented area is filled. I’d like to export the outline (external curve) of each segment for each slice in a specific plane, ideally as a list of 3D points.

I can export the solid models and work backwards from these to get the outlines, but was hoping that there was a quicker way to do this within Slicer?

Thanks,
Scott

You can use the hollow effect to get the surface. Then if you want the coordinates of the points you can export to labelmap and use numpy.where.

https://discourse.slicer.org/t/new-segment-editor-effect-for-creating-hollow-objects/2464