Error analysis about CCD sampling in Fourier transform profilometry

Chen, Wenjing; Li, Manhai; Su, Xin

doi:10.1016/j.ijleo.2008.02.012

Cited by 11 publications

(7 citation statements)

References 5 publications

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“…3(a), so it contains 9.8462 pixels in each period, and it can satisfy the conditions of sampling. [15,16] When the Fourier transform is applied to these deformed fringes, we can obtain the spectrum distribution of fringes along the x axis as shown in Fig. 3(b), and it can be seen clearly that there are overlapping phenomena between the first-order spectrum component and the adjacent periodic higher-order spectrum components due to the nonlinearity of the CCD under the actual conditions.…”

Section: Methodsmentioning

confidence: 99%

“…There are two kinds of spectrum overlap, one is produced by each order of spectrum situated in the same period, the other is produced by a "frequency island" caused by a lacking sample. [15,16] However, the latter can satisfy the conditions of the sample by using a CCD with higher resolving power to acquire a deformed fringe, namely, the number of samples in one period must exceed 4. [15,16] Because the object height information is contained in the first-order spectra, we may only discuss the spectrum overlapping between the first-order spectrum component f 1 and other components under the first condition.…”

Section: Influence Of Spatial Carrier Frequency Of Projection Gratingmentioning

confidence: 99%

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Effect of the nonlinearity of the CCD in Fourier transform profilometry on spectrum overlapping and measurement accuracy

Qiao¹,

Zou²

2013

Chinese Phys. B

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In Fourier transform profilometry (FTP), we must restrain spectrum overlapping caused by the nonlinearity of the charge coupled device (CCD) and increase the measurement accuracy of the object shape. Firstly, the causes of producing higher-order spectrum components and inducing spectrum overlapping are analysed theoretically, and a simple physical explanation and analytical deduction are given. Secondly, aiming to suppress spectrum overlapping and improve measurement accuracy, the influence of spatial carrier frequency of projection grating on them is analysed. A method of increasing the spatial carrier frequency of projection grating to restrain or reduce the spectrum overlapping significantly is proposed. We then analyze the mechanism of how the spectrum overlapping is reduced. Finally, the simulation results and experimental measurements verify the correction of the proposed theory and method.

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Section: Methodsmentioning

confidence: 99%

Section: Influence Of Spatial Carrier Frequency Of Projection Gratingmentioning

confidence: 99%

Effect of the nonlinearity of the CCD in Fourier transform profilometry on spectrum overlapping and measurement accuracy

Qiao¹,

Zou²

2013

Chinese Phys. B

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“…Real world digital imaging sensors consist of finite-area sensor elements, and the sampling performed by such devices is inherently an area sampling, with light being integrated over the sensor element convolved with the point spread function of the optics (Chen et al, 2009). While the actual sampling kernel of a real imaging device does not have a crisp edge or a rectangular shape, it is certainly much closer to an area sampling than to a point sampling.…”

Section: Overcoming the Constraints Of A Binary Imagementioning

confidence: 99%

Anti-aliased Euclidean distance transform

Gustavson

Strand

2011

Pattern Recognition Letters

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a b s t r a c tWe present a modified distance measure for use with distance transforms of anti-aliased, area sampled grayscale images of arbitrary binary contours. The modified measure can be used in any vector-propagation Euclidean distance transform. Our test implementation in the traditional SSED8 algorithm shows a considerable improvement in accuracy and homogeneity of the distance field compared to a traditional binary image transform. At the expense of a 10Â slowdown for a particular image resolution, we achieve an accuracy comparable to a binary transform on a supersampled image with 16 Â 16 higher resolution, which would require 256 times more computations and memory.

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“…Truncated Fourier series was used in [9] to represent and control shapes; This idea was generalized in [10] in the form of parameterized regression shape features. The classical Hu moments method [11] was extended in [12] to the case of visual contours by replacing the region integral with a curvilinear integral, which results in a reduced computation cost. Note that this promising approach has not yet been used in shape servoing.…”

Section: Introductionmentioning

confidence: 99%

Contour Moments Based Manipulation of Composite Rigid-Deformable Objects with Finite Time Model Estimation and Shape/Position Control

Qi¹,

Ma²,

Zhu³

et al. 2021

Preprint

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The robotic manipulation of composite rigiddeformable objects (i.e. those with mixed non-homogeneous stiffness properties) is a challenging problem with clear practical applications that, despite the recent progress in the field, it has not been sufficiently studied in the literature. To deal with this issue, in this paper we propose a new visual servoing method that has the capability to manipulate this broad class of objects (which varies from soft to rigid) with the same adaptive strategy. To quantify the object's infinite-dimensional configuration, our new approach computes a compact feedback vector of 2D contour moments features. A sliding mode control scheme is then designed to simultaneously ensure the finite-time convergence of both the feedback shape error and the model estimation error. The stability of the proposed framework (including the boundedness of all the signals) is rigorously proved with Lyapunov theory. Detailed simulations and experiments are presented to validate the effectiveness of the proposed approach. To the best of the author's knowledge, this is the first time that contour moments along with finite-time control have been used to solve this difficult manipulation problem.

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Error analysis about CCD sampling in Fourier transform profilometry

Cited by 11 publications

References 5 publications

Effect of the nonlinearity of the CCD in Fourier transform profilometry on spectrum overlapping and measurement accuracy

Effect of the nonlinearity of the CCD in Fourier transform profilometry on spectrum overlapping and measurement accuracy

Anti-aliased Euclidean distance transform

Contour Moments Based Manipulation of Composite Rigid-Deformable Objects with Finite Time Model Estimation and Shape/Position Control

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