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Flowchart of color random binary encoding scheme. (a)-(c) Three random binary patterns that are embedded into RGB channels (d)-(f) of one CRBEP (g).
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Acquiring the three-dimensional (3-D) surface geometry of objects with a full-frame resolution is of great concern in many applications. This paper reports a 3-D measurement scheme based on single-frame pattern projection in the combination of random binary encoding and color encoding. Three random binary encoding patterns generated by a computer e...
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... color channels of one color image only serve as the encoding carrier that is not involved in the searching behavior of homogeneous points. Figures 1(a)-1(c) show three random binary patterns. The smallest white (255) or black (0) square dot represents a pixel. ...
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... that is not involved in the searching behavior of homogeneous points. Figures 1(a)-1(c) show three random binary patterns. The smallest white (255) or black (0) square dot represents a pixel. By, respectively, encoding the three random binary patterns into the RGB channels shown in the second row of Figs. 1(d)-1(f), one CRBEP is created, as shown Fig. 1(g). This process can be formulated in Eq. (1). A digital projector receives the CRBEP and projects it onto the surface of the tested object, and two synchronized color cameras simultaneously capture the illuminated scene. Finally, the captured images are delivered to the computer for analysis and 3-D reconstruction E Q -T A R G E T ; t e ...
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... is different from each other in distribution, which is created using the MATLAB random binary encoding function. Details can be found in Figs. 1(a)-1(c) by close observation. ...
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... a moving palm with spatially discontinuous surface and different material properties from the mask is tested to illustrate the performance of our system for dynamic scenes. Since the color correction procedure of the object in Fig. 10(c)], indicating that the proposed encoding method and the reconstruction framework can achieve an acceptable accuracy for such a measurement task. It may be applied in fields like medical cosmetology and human motion analysis where the measurement time is ...
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Citations
... The addition of color information allows simultaneous threestep phase shifting (Tarini et al., 2005;Castillo et al., 2013;Flores et al., 2015;Trumper et al., 2016), multi-frequency display , or direction separation by color Wu et al., 2016;Ma et al., 2018;Xie et al., 2019), including simple multifrequency coding for easier unwrapping. Even discrete codes have been explored for use with colors (Xu et al., 2016;Zhou et al., 2017), and a combination of color and direction coding has been presented as well (Poirier-Herbeck et al., 2021). Color techniques of course work best on mirrors and glass, i.e., surfaces or media with no color of their own; but even then, one has to deal with the cross-talk ...
Deflectometry as a technique to assess reflective surfaces has now existed for some 40 years. Its different aspects and variations have been studied in multiple theses and research articles; reviews are available for certain subtopics. Still a field of active development with many unsolved problems, deflectometry now encompasses a large variety of application domains, hardware setup types, and processing workflows for different purposes, and spans a range from qualitative defect inspection of large vehicles to precision measurements of microscopic optics. Over these years, many exciting developments have accumulated in the underlying theory, in the systems design, and in the implementation specifics. This diversity of topics is difficult to grasp for experts and non-experts alike and may present an obstacle to a wider acceptance of deflectometry as a useful tool for research and industrial applications. This paper presents an attempt to summarize the status of deflectometry and to map relations between its notable branches. Its aim is to provide a communication basis for experienced practitioners and also to offer a convenient entry point for those interested in learning about the method. The list of references introduces some prominent trends and established research groups in order to facilitate further self-directed exploration.
... e folds of clothing are decorated for the ripples of the fabric, and the appearance has a strong sense of threedimensionality and simulation. Because folds are a diversified means of change, they can increase the aesthetics of clothing and show different styles of clothing [1,2,3]. In this way, for pleated fabric, the mutual conversion between the two-dimensional plane and three-dimensional is realized. ...
With the improvement of people's living standards, people's pursuit of clothing is becoming more and more diverse. As the main way to shape the external curve of the human body and reflect the texture of clothing materials, pleating technology is widely used in clothing. Different wrinkle expression techniques can often be seen in garment production and press conferences. Many designers are inseparable from the use of folding technology in their creation. The decoration of clothing is also constantly enriched. Diversified and multitype fabrics will bring great differences and influence to clothing and even affect the trend. Based on the computer animation technology, through the analysis of the principle of three-dimensional folds, this paper explores the formation of geometric patterns from two-dimensional plane fabric laying to three-dimensional, mainly through the techniques of pleating, kneading, lattice pleating, and pleating, so as to knead, stack or stack the fabrics orderly or randomly and naturally. The folded intersection area and nonfolded area are formed to form the basis of three-dimensional geometric folds. The simulation results show that the computer animation technology can effectively support the three-dimensional fold garment pattern design, select different materials for regional folding, present obvious three-dimensional geometric pattern folds, understand the expression forms of folds, and explain the application of folds in garment design, so as to provide some reference for fold garment design.
... The addition of color information allows simultaneous three-step phase shifting [352,[505][506][507], multi-frequency display [508], or direction separation by color [470,474,495,509], including simple multi-frequency coding for easier unwrapping. Even discrete codes have been explored for use with colors [430,510], and a combination of color and direction coding has been presented as well [511]. Color techniques of course work best on mirrors and glass, i.e. surfaces or media with no color of their own; but even then, one has to deal with the cross-talk between channels and the spectral dependence of the photon conversion efficiency. ...
Deflectometry as a technical approach to assessing reflective surfaces has now existed for almost 40 years. Different aspects and variations of the method have been studied in multiple theses and research articles, and reviews are also becoming available for certain subtopics. Still a field of active development with many unsolved problems, deflectometry now encompasses a large variety of application domains, hardware setup types, and processing workflows designed for different purposes, and spans a range from qualitative defect inspection of large vehicles to precision measurements of microscopic optics. Over these years, many exciting developments have accumulated in the underlying theory, in the systems design, and in the implementation specifics. This diversity of topics is difficult to grasp for experts and non-experts alike and may present an obstacle to a wider acceptance of deflectometry as a useful tool in other research fields and in the industry. This paper presents an attempt to summarize the status of deflectometry, and to map relations between its notable "spin-off" branches. The intention of the paper is to provide a common communication basis for practitioners and at the same time to offer a convenient entry point for those interested in learning and using the method. The list of references is extensive but definitely not exhaustive, introducing some prominent trends and established research groups in order to facilitate further self-directed exploration by the reader.
... With the release of some hit consumer electronics, i.e., Apple iPhone X, Microsoft Kinect V1, and Intel RealSence F200, laser speckle projection is becoming a popular single-shot method for 3D sensing. Compared with the projection system using a digital light projector (DLP), 4,5 (1) the laser speckle projection system can be more compact and miniaturized; (2) there is no defocusing issue in the laser speckle projection system; and (3) the speckle patterns generated by the laser are spatially more coherent and their brightness can be adjusted in a much larger range. 6,7 Laser speckles from these consumer electronics are invisible and are generated when an infrared (IR) laser beam passes through a specifically designed diffractive optical element (DOE). ...
Laser speckle is becoming popular for encoding objects for 3D profile reconstructions. However, the measurement accuracy of laser speckles based stereophotogrammetry is often not high due to the subjective speckles formed on the sensor plane of the camera. In this letter, we propose a method to enhance the measurement accuracy by encoding the surface of the object using red, green, and blue (RGB) laser speckles which are generated when a combined RGB laser beam passes through a ground glass diffuser. A 3CCD color camera is utilized to capture the object from two different perspectives. Interestingly, there is no crosstalk between different channels. Hence, the proposed system is practically equivalent to three synchronized monochrome vision systems having separate red, green, and blue laser speckle projections. Correspondences
located by the RGB speckle image correlation are more accurate, because the structured information in the color image is three times that in the monochrome image. Experimental results validate the higher accuracy of the proposed method against the conventional method using monochrome laser speckles. Moreover, the motion robustness of the proposed method is verified on the measurement of the moving objects.
... Although multi-shot RSP can improve the accuracy [8], [9], [20], they are not suitable for dynamic measurement. Recently, 3D shape measurement methods by a single-shot CRSP have been reported [41], [42]. A single-shot CRSP has the advantages of both single-shot RSP and multi-shot RSP. ...
Single-shot three-dimensional (3D) shape measurement techniques have attracted extensive researches, as they are suitable for dynamic measurement. In this study, a cost-effective single-shot structured light system (CES-SLS) is proposed for 3D shape measurement by using a color camera and a normal projector. With the aid of two planar mirrors and an isosceles right-angle mirror, a single color camera functions as a binocular vision. A single-shot color random speckle pattern (CRSP) is used to encode the object by a normal projector. The dense corresponding points (DCP) are derived by the spatial-temporal correlation of RGB image subsets instead of the spatial correlation of gray image subsets in the conventional method. Inverse compositional Gaussian Newton (IC-GN) iteration method with second-order shape function is then introduced to find the sub-pixel corresponding points (CP). Moreover, a geometrical 3D recovery method is presented to calculate the 3D point by minimizing the re-projection error. Experimental results demonstrate the comparative advantages of the proposed CES-SLS against the system using a single-shot random speckle pattern (RSP) and the curve fitting sub-pixel method in the aspects of measurement accuracy and noise robustness. In addition, the re-projection error of each 3D point from the geometrical method is smaller than that of the conventional mid-point.
... They are complicated and almost irreversible for the samples, and the microparticles may have a certain influence on 3D measurements. A method of projecting digital speckle patterns by means of a projector can conveniently create random features on the surface without affecting the samples, and has been applied to many macroscopic fields to achieve 3D measurements of simple shapes [34], human face [35], a Venus model [36], human body [37], a shape-complex mask [38], and different types of surfaces [39,40]. Whereas, this speckle projection method is rarely used in the field of microscopy. ...
Three-dimensional (3D) measurement of microstructures has become increasingly important, and many microscopic measurement methods have been developed. For the dimension in several millimeters together with the accuracy at sub-pixel or sub-micron level, there is almost no effective measurement method now. Here we present a method combining the microscopic stereo measurement with the digital speckle projection. A microscopy experimental setup mainly composed of two telecentric cameras and an industrial projection module is established and a telecentric binocular stereo reconstruction procedure is carried out. The measurement accuracy has firstly been verified by performing 3D measurements of grid arrays at different locations and cylinder arrays with different height differences. Then two Mitutoyo step masters have been used for further verification. The experimental results show that the proposed method can obtain 3D information of the microstructure with a sub-pixel and even sub-micron measuring accuracy in millimeter scale.
... Note that BWBSP is imaged by two 3060P gray cameras and its remaining physical parameters are the same with the color camera 3060CP. In order to ensure the accuracy of calibration when using 3060P gray and 3060CP color cameras, a mechanical mounting bracket with the same positioning holes are provided that enable them have the same baseline B. Besides, with the calibration method introduced in [36], 9 and 20 calibration images are respectively used that ensure their having similar calibration accuracy. Three patterns (1) CBSP shown in Fig. 2(d), (2) three BWBSPs (TBWBSP) shown in Figs. ...
... In the presence of colorful objects the measurement effect could be discounted since the physical property will override the projected color encoding pattern. Nevertheless, we have confirmed that only the R/G/B images separated from the captured CBSP image are not in saturation, different responses and color crosstalk amongst them have almost no influence on the result in measuring the same object whether or not color correction is used [36]. In this regard, it differs from [37] that a rigorous color correction is necessary. ...
This paper proposes a novel 3-D surface profile measurement scheme by only a single-shot color binary speckle pattern (CBSP) and a temporal–spatial correlation matching algorithm, which can be applied to measurements of dynamic and static objects. R/G/B channels of CBSP are coupled with three carefully designed black and white binary speckle patterns (BWBSPs), whose physical features are associated with the system configuration parameters. We mathematically deduce the concrete details of how to design such a pattern and its relationship with the system parameters selected in the experiment. During 3-D reconstruction, we develop an extended temporal-spatial correlation framework to determine the correspondence between two stereo images sequences that are composed of R/G/B images separated from a captured color stereo image pair. Comparative experiments and analysis are implemented to assess the measurement accuracy using standard workpieces (dumbbell and optical flat). The results indicate that the proposed approach enjoys better performance than the conventional BWBSP-based method in terms of spatial resolution, accuracy, and efficient reconstructed points. An experiment of applying CBSP to measuring a moving A4 paper is also presented, demonstrating the success of our computational framework. Finally discussions concerning the limitations of this method are implemented.
Industrial photogrammetry systems commonly require multiple coded targets to establish a global coordinate frame for relatively large objects. However, there are many industrial products that do not allow coded targets to be placed on their surfaces. We propose an accurate and dense point cloud generation approach for measuring large-sized, untextured objects. Unlike most existing industrial measurement methods, our photogrammetry approach is free of coded targets. We have three core contributions. First, a Rotation-Free Digital Image Correlation (RFDIC) method is proposed to improve the multi-view stereopsis matching precision. Second, based on the technique of structure from motion (SfM), a coarse-to-fine strategy is utilized to construct the multi-view geometry and accurately optimize camera poses. Third, the devices used are consumer-friendly and commonly available, i.e., only a digital projector and a camera are needed to obtain the dense points on the measured object surface. The experimental results show that the error of reconstructed length for a scale bar is less than 0.01 mm/m. Compared to the state-of-the-art commercial measurement system, the average error of point cloud reconstruction is about 0.055 mm, which meets the accuracy demand for industrial applications.
In this paper the design and construction of a low-cost 3D reconstruction and monitoring system using digital fringe projection (DFP) is proposed, which can perform small and large-scale measurements in different environments and can be applied to various applications such as intelligent monitoring, 3D online inspection, obstacle detection for vehicle guidance, etc. The contribution of this paper is threefold: a) development of a comprehensive 3D measuring system that performs sensors handling, coordinate acquisition, reconstruction, and display process simultaneously and quickly; b) proposal of new filters to improve quality and efficiency of the system; and c) development of a real-time virtual 3D measurement system to calibrate and analyze the proposed methodologies. Optical and simulation measurement results are presented to verify the feasibility and performance of the developed systems. The observed RMS difference was found to be less than 0.021 mm in the optical measurement. From measured results, it can be concluded that the proposed systems and adopted methodology are effective in obtaining 3D surface profiles.
