Hi Vladimir, I'm sorry but I'm still not understanding what to look for.

Are you seeing a difference in shape? In number of segments? I tried moving the curves on top of each other to look for variations in shape but all 3 versions seem to stack up exactly on top of each other.

Is it that the red curves are not detected as arcs in the last set? That's probably because they were arcs of very large radius values so they're very close to being lines.

- Michael