BiarcTangents

The direction of the Catmull-Rom spline through the points, with knot spacing |Δp|^alpha: 0.0 is uniform, 0.5 centripetal and 1.0 chordal. At the ends of an open polyline the tangent is that of the next point mirrored in the end edge, so the end edges are single arcs. Usually loops less than Circle on scattered points.

The direction of the circle through the point and its neighbours. Points on a circle give that circle, but at sharp corners the direction can point back against the next edge, which gives large loops.