301967.fig.004a
(a) Level 1
301967.fig.004b
(b) Level 2
301967.fig.004c
(c) Level 3
Figure 4: It shows the comparison at 1st, 2nd, and 3rd level of binary, ternary, and quaternary 4-point approximating schemes. Dotted lines indicate initial control polygons, whereas dashed, thin solid, and bold solid continuous curves are generated by binary, ternary, and quaternary schemes, respectively.