As the author puts it [0], the issue is that if you expand or contract an ellipse by a fixed radius in every direction (e.g., if you create inner and outer wall

As the author puts it [0], the issue is that if you expand or contract an ellipse by a fixed radius in every direction (e.g., if you create inner and outer walls for an elliptical corridor of constant width), then the resulting curve is no longer an ellipse. In contrast, piecewise-circular arcs can be expanded or contracted and remain piecewise-circular, though the control points will shift around as you transform it. [0] https://medium.com/@brunopostle/hey-ovals-are-better-than-ellipses-for-buildings-e8de4a9ae7b4 https://medium.com/@brunopostle/hey-ovals-are-better-than-el...