# Thread: Build a Clothoid segment

1. ## Build a Clothoid segment

Hi,

I am trying to create a graphical interface which the user can use to build course tracks, i.e. roads. And for that I have to use clothoid segments (just like for normal highway constructions), but I don't really understand the math behind it.

For the graphically created course the user has to get back as data the start and end curvature and the curve length. I know that the curvature could be calculated using the radius, i.e. curvature = 1/R. But how can I calculate it when no radius is given? Can the tangents to the start and the end points of the segment influence the curvature? If so, how?

Hope you can help me.

2. ## Re: Build a Clothoid segment

Originally Posted by schmimona
Hi,

I am trying to create a graphical interface which the user can use to build course tracks, i.e. roads. And for that I have to use clothoid segments (just like for normal highway constructions), but I don't really understand the math behind it. <-- then you definitely have a problem!

For the graphically created course the user has to get back as data the start and end curvature and the curve length. I know that the curvature could be calculated using the radius, i.e. curvature = 1/R. But how can I calculate it when no radius is given? Can the tangents to the start and the end points of the segment influence the curvature? If so, how?

Hope you can help me.
Maybe this is of some help: Euler spiral - Wikipedia, the free encyclopedia