Double three-step phase-shifting algorithm

Huang, Peisen S.; Hu, Qingying; Chiang, Fu‐Pen

doi:10.1364/ao.41.004503

Cited by 124 publications

(56 citation statements)

References 11 publications

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“…Our solution was to shoot two images of each fringe projection with different exposure values, resulting in a high dynamic range. Therefore we employed the double three-step fringe projection method [18], where the second projection sequence had a different exposure setting. The capture of one scene currently takes around a minute, depending on the settings.…”

Section: Softwarementioning

confidence: 99%

Simultaneous capture of the color and topography of paintings using fringe encoded stereo vision

et al. 2014

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Introduction: Paintings are versatile near-planar objects with material characteristics that vary widely. The fact that paint has a material presence is often overlooked, mostly due to the fact that we encounter many of these artworks through two dimensional reproductions. The capture of paintings in the third dimension is not only interesting for study, restoration and conservation, but it also facilitates making three dimensional reproductions through novel 3-D printing methods. No single imaging method is ideally suited to capture the painting's color and topography and each of them have specific drawbacks. We have therefore designed an efficient hybrid imaging system dedicated to capturing paintings in both color and topography with a high resolution. Results: A hybrid solution between fringe projection and stereo imaging is proposed involving two cameras and a projector. Fringe projection is aided by sparse stereo matching to serve as an image encoder. These encoded images processed by the stereo cameras then help solve the correspondence problem in stereo matching, leading to a dense and accurate topographical map, while simultaneously capturing its color. Through high-end cameras, special lenses and filters we capture a surface area of 170 square centimeter with an in-plane effective resolution of 50 micron and a depth precision of 9 micron. Semi-automated positioning of the system and data stitching consequently allows for the capture of larger surfaces. The capture of the 2 square meter big Jewish Bride by Rembrandt yielded 1 billion 3-D points. Conclusion:The reproductive properties of the imaging system are conform the digitization guidelines for cultural heritage. The data has enabled us to make high resolution 3-D prints of the works by Rembrandt and Van Gogh we have captured, and confirms that the system performs well in capturing both the color and depth information.

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Section: Softwarementioning

confidence: 99%

Simultaneous capture of the color and topography of paintings using fringe encoded stereo vision

et al. 2014

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“…In general though, accuracy depends on the projector characteristics as a whole, as discussed in [14]. It has been demonstrated [7] that these errors can be somewhat alleviated by using a larger number of fringe patterns, however for dynamic applications requiring fast reconstruction (such as FTP and 3-step or 4-step profilometry [15,16]) the non-sinusoidal phase error is considered as the dominant error source. As a matter of fact, non-linearity of the video projector is mainly due to gamma correction for image enhancement which inevitably decreases the accuracy and resolution of the measurement.…”

Section: Related Workmentioning

confidence: 99%

Stable and fast techniques for unambiguous compound phase coding

Torsello

Albarelli

Rodolà

2013

Image and Vision Computing

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a b s t r a c t a r t i c l e i n f oPhase shift methods have proven to be very robust and accurate for photometric 3D reconstruction. One problem of these approaches is the existence of ambiguities arising from the periodicity of the fringe patterns. While several techniques for disambiguation exist, all of them require the projection of a significant number of additional patterns. For instance, a global Gray coding sequence or supplemental sinusoidal patterns of different periods are commonly used to complement the basic phase shift technique. In this paper we propose four new coding strategies that encode the index of the projected column using several phases and that mix the resulting phases into a controllable number of projected patterns from which the position can be recovered with subpixel precision. One notable characteristic of the proposed approaches is that we can allocate the additional number of patterns specifically to improve precision or provide higher robustness to noise. The proposed approaches are analyzed and compared with the state of the art, showing their ability to be tuned towards high precision in low noise conditions or robustness with respect to noise.

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“…Huang et al proposed a double three-step phase-shifting algorithm and the error level has been reduced to less than half. 7 Pan et al presented an iterative method and simplified phase error to one order. 8 Guo et al have proposed a gamma-correction technique on the basis of statistical analysis of the fringe images.…”

Section: Introductionmentioning

confidence: 99%

Phase error elimination considering gamma nonlinearity, system vibration, and noise for fringe projection profilometry

et al. 2014

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Abstract. Fringe projection profilometry (FPP) using a digital video projector is widely used for three-dimensional shape measurement. However, the gamma nonlinearity, system vibration, and noise cause the captured fringe patterns to be nonsinusoidal waveforms and have a grayscale deflection from their true value. This leads to an additional phase measurement error for a general phase-shifting algorithm. Based on the theoretical analysis, we propose a method to eliminate the phase error considering two factors. In this method, four-step phaseshifting is done four times with an initial phase offset of 22.5 deg and the average of these four phase maps precisely results in the real phase. As a result, phase error caused by gamma nonlinearity can be effectively suppressed. In addition, every image in phase shifting is replaced by the average of 20 fringe images continuously captured at the same state to avoid the phase error caused by system vibration and noise. Experimental results show that this method is effective in eliminating the phase error in practical phase-shifting FPP. In general, more than 90% of the phase error can be reduced.

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Double three-step phase-shifting algorithm

Cited by 124 publications

References 11 publications

Simultaneous capture of the color and topography of paintings using fringe encoded stereo vision

Simultaneous capture of the color and topography of paintings using fringe encoded stereo vision

Stable and fast techniques for unambiguous compound phase coding

Phase error elimination considering gamma nonlinearity, system vibration, and noise for fringe projection profilometry

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