Using the toe and heel points found in "Method 2: Curvature", a triangle is fitted to the foot. The ankle point is the third vertex of the triangle. The ankle point is assumed to be the foci of an ellipse fitted to the calf. The other foci of the calf ellipse is used as the foci of the ellipse fitted to the thigh. Below are several images with the triangle and ellipses fitted to the legs.