> Your visual system can actually see those discontinuities. Because it's also the biggest difference of curvature (actually the radius of curvature, the inver

> Your visual system can actually see those discontinuities. Because it's also the biggest difference of curvature (actually the radius of curvature, the inverse of the curvature value, which is what is geometrically significant, "what we see") possible, the one between infinity (a line is a circle with an infinite radius) and a "normal" (finite) value.