Three-dimensional shape measurement of non-full-field reflective surfaces (original) (raw)

A structured lighting for 3D shape measurement of glass surface

2009

This paper describes an optical technique that enables 3D measurement of a shiny surface by reflection of a regular pattern. The technique called “deflectometry” has already been used to detect curvature defects. We have developed a calibration procedure in order to quantify the gathered information and enable a 3D reconstruction of the surface. We give a detailed description of the setup as well as the calibration procedure. Then we present the results of a metrology study that allows an assessment of the global uncertainty of the measurements. Applications in the car industry are then presented. Introduction – The 3D measurement of shiny surfaces Optical techniques that enable quick and global 3D measurement of surfaces are more and more accepted and used in industry, in particular because of a better knowledge of their metrological characteristics. Structured lighting is an optical technology based on fringes projection that allows quick 3D digitization of manufactured parts. The...

A new phase extraction algorithm for phase profilometry

Machine Vision and Applications, 1997

This paper describes a new phase extraction algorithm for 3D optical profilometry based on the projection of a periodic light pattern and phase measurement (phase profilometry). The algorithm uses a square wave to demodulate phase and moving averages and comb-shaped filters to extract the phase information from low frequency. The proposed algorithm is compared with the two major profilometry techniques, namely Fourier domain profilometry and signal domain profilometry based on FIR low-pass filtering. Comparison is focused on adaptiveness to changes of the pattern frequency, ability to deal with nonuniform surfaces and computational complexity. Adaptiveness analysis is carried out by means of simulations. The issue of nonuniform surfaces is discussed on the basis of experimental results obtained from application of phase profilometry to on-line 3D printed circuit board inspection. With regard to complexity, theoretical estimates are verified by means of actual computation time measurements.

Review of phase measuring deflectometry

As a low cost, full-field three-dimensional shape measurement technique with high dynamic range, Phase Measuring Deflectometry (PMD) has been studied and improved to be a simple and effective manner to inspect specular reflecting surfaces. In this review, the fundamental principle and the basic concepts of PMD technique are introduced and followed by a brief overview of its key developments since it was first proposed. In addition, the similarities and differences compared with other related techniques are discussed to highlight the distinguishing features of the PMD technique. Furthermore, we will address the major challenges, the existing solutions and the remaining limitations in this technique to provide some suggestions for potential future investigations.

Comparison of Camera Calibration and Measurement Accuracy Techniques for Phase Measuring Deflectometry

Applied Sciences, 2021

Phase measuring deflectometry (PMD) is a competitive method for specular surface measurement that offers the advantages of a high dynamic range, non-contact process, and full field measurement; furthermore, it can also achieve high accuracy. Camera calibration is a crucial step for PMD. As a result, a method based on the calibration of the entrance pupil center is introduced in this paper. Then, our proposed approach is compared with the most popular photogrammetric method based on Zhang’s technique (PM) and Huang’s modal phase measuring deflectometry (MPMD). The calibration procedures of these three methods are described, and the measurement errors introduced by the perturbations of degrees of freedom in the PMD system are analyzed using a ray tracing technique. In the experiment, a planar window glass and an optical planar element are separately measured, and the measurement results of the use of the three methods are compared. The experimental results for the optical planar eleme...

A novel phase measuring deflectometry for aspheric mirror test

Optics Express, 2009

A method based on fringe reflection is presented to measure the aspheric mirror with higher precise. This method measures the absolute height of the aspheric mirror with dummy paraboloid, while the camera is located beside the optical axis of the test surface. It can be used to measure the aspheric mirror with high deviation. And for locating the camera beside the optical axis, this method doesn't have occlusion problem and can do the measurement more flexibility. Furthermore, compared with the traditional PMD, this method measures the tested surface with dummy paraboloid instead of the intersection of two straight lines, so it doesn't need to calibrate the image projection vectors. And the errors of the calibration influence this method less than the traditional method. Therefore, this method can measure the high deviation aspheric mirror with higher precise even if the calibration precise isn't very high. Computer simulations and preliminary experiment validate the feasibility of this method.

Technique for Phase Measurement and Surface Reconstruction by Use of Colored Structured Light

Applied Optics, 2002

We present a new method for improving the measurement of three-dimensional ͑3-D͒ shapes by using color information of the measured scene as an additional parameter. The widest used algorithms for 3-D surface measurement by use of structured fringe patterns are phase stepping and Fourier fringe analysis. There are a number of problems and limitations inherent in these algorithms that include: that the phase maps produced are wrapped modulo 2, that in some cases the acquired fringe pattern does not fill the field of view, that there may be spatially isolated areas, and that there is often invalid and͞or noisy data. The new method presented to our knowledge for the first time here uses multiple colored fringe patterns, which are projected at different angles onto the measured scene. These patterns are analyzed with a specially adapted multicolor version of the standard Fourier fringe analysis method. In this way a number of the standard difficulties outlined above are addressed.

A New Calibration Procedure for 3-D Shape Measurement System Based on Phase-Shifting Projected Fringe Profilometry

IEEE Transactions on Instrumentation and Measurement, 2000

An original procedure is presented for the calibration of fringe-projection-based 3-D vision systems. The proposed approach estimates both the phase-to-depth and transverse relationships by directly measuring the phase maps for only three planes placed within the calibration volume and then estimating the phase maps for a number of other "virtual planes." Experimental tests conducted on a fringe projection system show the effectiveness of the proposed procedure.

Three-dimensional inspection of printed circuit boards using phase profilometry

1996

Reconstruction of 3D shape of the solder paste printed on SMT component pads is a major inspection task in the PCB manufacturing process. The paper reports on the use of phase pro lometry for this inspection task. In phase pro lometry a structured light pattern is projected onto the object and viewed by a camera. Since the imaged pattern is phase-modulated according to the topography of the object, the extraction of phase information from the image enables reconstructing the 3D shape. In this paper two phase-extraction methods, Fourier Transform Pro lometry and Signal Domain Prolometry, are compared by means of simulations and experiments. Results show that the Fourier method performs better, yielding neat detection of the elevation with respect to PCB surface associated with solder paste.

A 3D vision system based on one-shot projection and phase demodulation for fast profilometry

Measurement Science & Technology, 2005

We present a 3D vision system based on the projection of a single fringe pattern of incoherent light and on robust phase coding. A novel projection scheme is exploited: two sinusoidal gratings at different frequencies are combined into a single pattern, and phase demodulated in the natural domain of the signal. The method yields the determination of two phase maps, whose sensitivity to height variations is proportional to the frequencies of the two grating components. Robust phase unwrapping is implemented, where the phase ambiguity of the fine grating component is naturally compensated for by the phase values evaluated by using the coarse one. As a result, both a high measurement resolution and an extended height range are obtained. The method requires the projection of a static pattern. Hence, even a low-cost slide projector can be used as the projection device. Moreover, the system turns out to be suitable for dynamic and real-time measurement applications. In addition, it may be fruitfully used as the acquisition sensor in full-optical reverse engineering applications. In this paper, the measurement principle and the design issues of the instrument are presented. The measurement performances are discussed, in relation to both the input-output characteristic of the instrument and the acquisition of free-form shapes.