Fig. 3.

Iterative process with 2D space and 1D camera imaging plane. P₁, P₂, P₃ and P₄ are the object points; P₁ is selected as the control point (o = 1). (a) The process ${\mathbf{p}}^{\left(k\right)}\to {\mathbf{q}}^{\left(k+1\right)}\to {\mathbf{p}}^{\left(k+1\right)}\to \hspace{0.17em}\dots$ makes the estimation pose approach the correct solution; (b) the rotation related to p^(k+1) is worse than that related to p^(k), which means the process is approaching a local minima, which is a mirror-image form of the true object shape.