# Clothoid

Clothoids (also called Euler spirals, spiros, Cornu spirals, or transition curves) are curves whose curvature changes linearly as a function of length.

A clothoid in FME is defined by start curvature, end curvature, clothoid length, start position, and start direction. To create a clothoid whose elevation is a linear function of length, start/end elevations may also be defined. If a transformation matrix is supplied for the clothoid, global start and end coordinates may also be defined by editing the custom XML in the Creator transformer.