Spline

A 3D spline is a mapping from a 1D parameter to 3D points \((z, y, x)\):

\[ \boldsymbol{C}(u) \in \mathbb{R}^3 \quad (0\le u \le 1) \]

Splines are used to represent filamentous structures in the tomograms. In cylindra, several useful methods are provided to make the most of splines.

• Clip and Invert Splines
• Spline Configurations
• Annotate Segments on Splines
• Spline 3D interactivity

How to fit splines to structures is described here.