CC Visualization fix

[ClePol]

This PR fixed a small bug that would affect visualization of corpus callosum thickness estimates. Interpolation of thickness values could fail when the interpolated point and the original closest point would be equal, causing nan values in the results.

The fix is to take the value of the equal point directly, instead of weighting by distance.

[Copilot]

Pull request overview

This PR fixes NaN thickness values in corpus callosum thickness visualization by handling the zero-distance interpolation case explicitly (when an interpolated point coincides with an existing contour point).

Changes:

• Update insert_point_with_thickness() to detect existing points (within a tolerance) and return the existing index instead of inserting a duplicate point.
• Extend insert_point_with_thickness() return (when return_index=True) with an inserted: bool flag and adjust endpoint index bookkeeping accordingly.
• Guard fill_thickness_values() against divide-by-zero by directly using the thickness value(s) of zero-distance neighbor(s).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
CorpusCallosum/shape/thickness.py	Avoids duplicate-point insertion and propagates an inserted flag to prevent incorrect endpoint index shifts.
CorpusCallosum/shape/contour.py	Prevents NaNs during thickness interpolation when closest-distance is effectively zero.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.