C¹ analysis of 2D subdivision schemes refining point-normal pairs with the circle average

This article continues the investigation started in [9] on subdivision schemes refining 2D point-normal pairs, obtained by modifying linear subdivision schemes using the circle average. While in [9] the convergence of the Modified Lane-Riesenfeld algorithm and the Modified 4-Point schemes is proved, here we show that the curves generated by these two schemes are $C^1$.