“…The authors of [9] showed elegantly that odd rational support functions correspond to those rational surfaces which can be equipped with a linear field of normal vectors (LN surfaces), and then that their offsets are rational constant width surfaces. The planar version can also be deduced from [22], where it is noted that any rationally parameterized curve is Pythagorean-hodograph, and thus, it has a rational offset. For this reason and by Remark 1, we can focus without loss of generality on discussing what a support function of a rational projective hedgehog must be.…”