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Fangxiaoyu Feng

Bio: Fangxiaoyu Feng is an academic researcher from Nanjing University of Science and Technology. The author has contributed to research in topics: Structured-light 3D scanner & Spatial frequency. The author has an hindex of 6, co-authored 6 publications receiving 551 citations.

Papers
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Journal ArticleDOI
TL;DR: A high-speed three-dimensional shape measurement technique for dynamic scenes by using bi-frequency tripolar pulse-width-modulation (TPWM) fringe projection to generate ideal fringe patterns with slight defocus is introduced.

302 citations

Journal ArticleDOI
TL;DR: An easy-to-implement three-dimensional (3-D) real-time shape measurement technique using the authors' newly developed high-speed 3-D vision system that employs only four projection fringes to realize full-field phase unwrapping in the presence of discontinuous or isolated objects.
Abstract: This paper describes an easy-to-implement three-dimensional (3-D) real-time shape measurement technique using our newly developed high-speed 3-D vision system. It employs only four projection fringes to realize full-field phase unwrapping in the presence of discontinuous or isolated objects. With our self-designed pattern generation hardware and a modified low-cost DLP projector, the four designed patterns can be generated and projected at a switching speed of 360 Hz. Using a properly synchronized high-speed camera, the high-speed fringe patterns distorted by measured objects can be acquired and processed in real-time. The resulting system can capture and display high-quality textured 3-D data at a speed of 120 frames per second, with the resolution of 640 × 480 points. The speed can be trebled if a camera with a higher frame rate is employed. We detail our shape measurement technique, including the four-pattern decoding algorithm as well as the hardware design. Some evaluation experiments have been carried out to demonstrate the validity and practicability of the proposed technique.

194 citations

Journal ArticleDOI
TL;DR: This work finds that by properly optimizing SPWM patterns according to some criteria, and combining SPWM technique with four-step phase-shifting algorithm, the dominant undesired harmonics will have no impact on the phase obtained.
Abstract: Three-dimensional profilometry by sinusoidal fringe projection using phase-shifting algorithms is usually distorted by the nonlinear intensity response of commercial video projectors. To overcome this problem, several methods including sinusoidal pulse width modulation (SPWM) were proposed to generate sinusoidal fringe patterns with binary ones by defocusing the project to some certain extent. However, the residual errors are usually nonnegligible for highly accurate measurement fields, especially when the defocusing level is insufficient. In this work, we propose two novel methods to further improve the defocusing technique. We find that by properly optimizing SPWM patterns according to some criteria, and combining SPWM technique with four-step phase-shifting algorithm, the dominant undesired harmonics will have no impact on the phase obtained. We also propose a new sinusoidal fringe generation technique called tripolar SPWM, which can generate ideal sinusoidal fringe patterns with a very small degree of defocusing. Simulations and experiments are presented to verify the performance of these two proposed techniques.

114 citations

Journal ArticleDOI
TL;DR: This work presents a novel approach for identifying those invalid pixels affected by such an error by carefully examining the captured fringe pattern, comparing two modulation maps, utilizing the phase relationship between two neighboring pixels, and employing a Gaussian filter to detect the protruding points.
Abstract: Phase-shifting profilometry combining with the two-frequency temporal phase unwrapping is widely used for high-speed, real-time acquisition of three-dimensional shapes. However, when the object is not motionless during the acquisition process, some unreliable results may emerge, especially around the contours of the measured object. The main reason for this is that the same point in the projected pattern sequence can map to different points within the camera images resulting from depth changes over time. We present a novel approach for identifying those invalid pixels affected by such an error. By carefully examining the captured fringe pattern, comparing two modulation maps, utilizing the phase relationship between two neighboring pixels, and employing a Gaussian filter to detect the protruding points, the bad measurement pixels can be detected and filtered out effectively. The whole procedure is of low computational complexity because of the introduced lookup table-based fast data processing method. Some experimental results are presented to verify the validity of our method. © 2013 Society of Photo-Optical

40 citations

Patent
06 Feb 2013
TL;DR: In this article, a method for constructing a sinusoidal grating during three-dimensional optical measurement on the basis of three-grayscale spatial pulse width modulation is described. But the method is not suitable for high-dimensional measurements.
Abstract: The invention discloses a method for constructing a sinusoidal grating during three-dimensional optical measurement on the basis of three-grayscale spatial pulse width modulation. The method comprises the following steps of: grating coding: a grating coding stripe image is generated through a computer; grating projecting: digital projection equipment is used to project the rating coding stripe image; and projection equipment defocusing: the projection equipment is slightly defocused finally. The projection equipment does not need complicated nonlinear calibration, additional grating strips or a late compensation algorithm is also not needed, hardware facility is not required to be additionally arranged, but the grating stripe image with standard sinusoidal light distribution can be obtained, so that the method is simple and practicable and has a good application prospect.

7 citations


Cited by
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Journal ArticleDOI
TL;DR: An overview of state-of-the-art phase shifting algorithms for implementing 3D surface profilometry is presented to provide a useful guide to the selection of the most appropriate phase shifting technique for a particular application.

611 citations

Journal ArticleDOI
TL;DR: The results show that the multi-frequency temporal phase unwrapping provides the best unwrapped reliability, while the multi -wavelength approach is the most susceptible to noise-induced unwrappers errors.

598 citations

Journal ArticleDOI
Song Zhang1
TL;DR: The fundamental principles behind the primary state-of-the-art 3D shape measurement techniques based on structured light methods will be elucidated, experimental results will be presented to demonstrate capabilities and/or limitations for those popular techniques, and perspectives on those remaining challenges to be conquered to make advanced 3Dshape measurement techniques ubiquitous are presented.

514 citations

Journal ArticleDOI
TL;DR: A high-speed three-dimensional shape measurement technique for dynamic scenes by using bi-frequency tripolar pulse-width-modulation (TPWM) fringe projection to generate ideal fringe patterns with slight defocus is introduced.

302 citations

Journal ArticleDOI
TL;DR: The current state-of-the-art in structured light profilometry systems is described, as well as the main advancements in hardware technology and coding strategy that have led to their successful development.

286 citations