The fringe projection technique is an effective technique to measure 3D shape of objects, in which phase retrieval is an important procedure. In this paper, the phase extraction algorithm of random phase-shift, which can be used in the fluctuating light source and the non-uniform background intensity and modulation amplitude, is proposed. The proposed method can retain more details of reconstructed phase than Fourier transform profilometry. Compared with multi-frame phase-shifting method, the proposed method only needs two fringe patterns to extract the phase and phase shift of the object. Our method consists of two stages. Firstly, the method is built based upon Lissajous Ellipse Fitting technique that extracts the phase from only two phase-shifted fringes which may contain arbitrary and unknown phase shift in dynamic measurement experiment. Second, the non-uniform background intensity and modulation amplitude are removed. The simulation results demonstrate that the proposed method can effectively obtain the phase.
Structured light three-dimensional (3D) measurement techniques have obtained increasing popularity in the field of industrial automation, inverse engineering, and graphics. Recent literatures show that the imperfect of the imaging system in the structured light 3D metrology will cause the discontinuous-induced measurement artifact (DMA) in the area around the discontinuous edge. Existing DMA reduction methods need to detect the all edges accurately first. This procedure is hard to accomplish when the edges are defocused. Meanwhile, the corrected date in the error area relies heavily on the data in its nearest unaffected area, which makes the corrected data unreliable in some situations. In this work, a flexible deconvolution-based method is proposed to solve the above two problems in this paper. Simulation and experiment show that our proposed method can reduce the Root Mean Square phase/height error of DMA by up to 4 times.
KEYWORDS: Diffusers, Cameras, Calibration, 3D modeling, Data modeling, Light scattering, Scattering, Scattering media, 3D acquisition, 3D image processing
Wide-field depth-resolved imaging through scattering media has been a longstanding problem in recent years. In this paper, we proposed a reference-less compact imaging physical model, where the 3D light field data embedded in the volumetric speckle stack through a strong diffuser is explored and analyzed. By utilizing wave-optics and a coherent round-trip field estimation method, the scattering matrix of the diffuser is precisely calibrated as a priori knowledge. After then, the multi-slice targets are placed between the light source and the diffuser, and a set of defocused intensity pattern are recorded for recovering the scattered object field. The real object field is extracted from inverse diffracting of the field employing the conjugation of the calibrated scattering matrix. Wide-field imaging is verified experimentally by recording a resolution chart hidden behind a ground glass. The technique shows great potential in lens-less wave-front sensing and non-reference 3D imaging.
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