Figure 13.

Sequence of views. Blue and red arrows indicate local minima and maxima respectively, of the sequence $\mathcal{B}=\left\{b_i\right\}$ of the semi-minor axis. If the sequence $\mathcal{B}$ is increasing at instant i, then $\theta >0$. This means (for this direction of rotation) that the part below the fruit center in the view is higher than the part above the center.