Two-wavelength polarization-encoded structured light technique for fast 3D reconstruction of high-reflective objects

Fringe projection profilometry (FPP) is one of the most popular 3D sensing techniques and is widely used due to its flexibility, high resolution and high speed. However, the conventional FPP has errors in absolute phase and 3D reconstruction results when measuring the surfaces of high-reflective objects because the fringe images contain some overexposed areas. To solve this problem, a two-wavelength polarization-encoded structured light method is proposed in this paper, which takes advantages of the properties of commercial liquid crystal display (LCD) projector to modulate the intensity and polarization state of the projected light simultaneously, and use two mutually perpendicular polarization states to project two fringe patterns with different frequencies. The polarization camera can capture them in separate polarization channels to achieve the desired phase unwrapping. The proposed method enhances the stability of the fringes, reduces the required fringe pattern by half, and increases the measurement speed. Experimental results show that the proposed method can suppress the phase error in the highlighted region when reconstructing high-reflective surfaces, obtain accurate absolute phase and reliably perform 3D reconstruction.