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Illustration of the ellipse parameters curvature (C), arc length (Δs) and turning angle (Δφ). C max and C min represent points of local maximum and minimum curvature. The arc length between two of these local extrema is Δs e. The dashed lines mark the points halfway the local extrema, hence the arc length between these points is also Δs e. Tangent lines are drawn at these places. The turning angles between two subsequent tangent lines are represented by Δφ 1 and Δφ 2, respectively
