Specular reflection compensation in homography fringe projection profilometry

Fringe projection profilometry (FPP) is widely used in the industrial 3D measurement. When measuring an object using FPP, inclined projection will cause problems of periodic inconsistency and light-intensity inhomogeneity to fringe patterns. This paper presents an improved homography fringe generation method to correct the fringes. In this paper, a homography transform is used not only for the coordinate transformation between the projection plane and the reference plane, but also for the modulation of the period and light intensity of the fringe. Based on this method, the captured fringe patterns have good periodicity and homogenized intensity, meanwhile, the impact of high reflection is evidently weakened in the recovery of 3D surface shape with specular component, thus effectively reducing the phase errors. Experiments show that the 3D rail shape is well recovered and the error is apparently decreased based on the proposed method.