Phase error correction method for fringe projection profilometry systems while considering random noises and objects' reflectivity

Measuring objects with drastic texture variation is a big challenge for fringe projection profilometry (FPP) systems. In this paper, the reasons why textures on measured objects' surface influence the measurement accuracy are thoroughly analyzed and an effective phase error compensation method is proposed. Due to the existence of various random noises, the reconstruction accuracy will be negatively affected by the textures with different reflectivity. As an intrinsic feature of digital cameras, random noises be hardly removed by mathematical solutions. In this paper, it is mathematically proved that image pixels with the same fringe modulation have the same noise variance and the same phase error variance. With the aid of fringe orientations calculated in the phase map, pixels which satisfy the following two conditions are picked out as a group: 1. They should have the same phase. 2. They have almost the equivalent modulation values. Then the phase values of this group of pixels are averaged and this mean phase is the compensated phase value. Experiments demonstrate that the proposed method can effectively reduce phase errors caused by random noises and textures with small reflectivity.