Geometric Stratification for Singular Configurations of the P3P Problem via Local Dual Space

This paper investigates singular configurations of the P3P problem. Using local dual space, a systematic algebraic-computational framework is proposed to give a complete geometric stratification for the P3P singular configurations with respect to the multiplicity $\mu$ of the camera center $O$: for $\mu \ge 2$, $O$ lies on the ``danger cylinder’', for $\mu \ge 3$, $O$ lies on one of three generatrices of the danger cylinder associated with the first Morley triangle or the circumcircle, and for $\mu \ge 4$, $O$ lies on the circumcircle which indeed corresponds to infinite P3P solutions. Furthermore, a geometric stratification for the complementary configuration $O^{\mathrm{\prime }}$ associated with a singular configuration $O$ is studied as well: for $\mu \ge 2$, $O^{\mathrm{\prime }}$ lies on a deltoidal surface associated with the danger cylinder, and for $\mu \ge 3$, $O^{\mathrm{\prime }}$ lies on one of three cuspidal curves of the deltoidal surface.