Three-dimensional profile measurement of steep object by optical fiber frequency mixing fringe projection technology

2007 ◽  
Author(s):  
Xiaoyan Lin ◽  
Libo Yuan
Keyword(s):  
Optical Fiber ◽  
Three Dimensional ◽  
Fringe Projection ◽  
Profile Measurement ◽  
Frequency Mixing

scholarly journals Fringe projection profilometry for recovering 2.5D shape of ancient coins

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 142
Author(s):  
Giuseppe Schirripa Spagnolo ◽  
Lorenzo Cozzella ◽  
Fabio Leccese
Keyword(s):  
Cultural Heritage ◽  
Good Accuracy ◽  
Three Dimensional ◽  
Surface Profile ◽  
Fringe Projection ◽  
Profile Measurement ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Cultural Heritage Objects ◽  
Physical Access

<p class="Abstract">The relief of form is undoubtedly one of the most topical topics in the field of cultural heritage. Physical access to historic and artistic manufactures can be limited by a lot of factors. For example, the access to the collection of the ancient coins is difficult, especially for students. Indeed, for coins digital archive of high-quality three-dimensional model and remote fruition is of great interest. The use of projected fringes for the measurement of surface profile is a well-developed technique. In this paper, we present a surface profile measurement system for small objects of cultural heritage where it is important not only to detect the shape with good accuracy but also to capture and archive the signs due to ageing. The illustrated equipment is simple, reliable, and cheap. Furthermore, some examples of acquisitions are presented to demonstrate the potentiality of the proposed scheme for recovering 2.5D shape of cultural heritage objects.</p>

A New Three-Dimensional Profilometer for Surface Profile Measurement Using Digital Fringe Projection and Phase Shifting

2005 ◽  
Vol 295-296 ◽  
pp. 471-476
Author(s):  
Liang Chia Chen ◽  
S.H. Tsai ◽  
Kuang Chao Fan
Keyword(s):  
High Speed ◽  
Structured Light ◽  
Three Dimensional ◽  
Surface Profile ◽  
Phase Shifting ◽  
Fringe Projection ◽  
Surface Measurement ◽  
Profile Measurement ◽  
Digital Fringe Projection ◽  
Fringe Patterns

The development of a three-dimensional surface profilometer using digital fringe projection technology and phase-shifting principle is presented. Accurate and high-speed three-dimensional profile measurement plays a key role in determining the success of process automation and productivity. By integrating a digital micromirror device (DMD) with the developed system, exclusive advantages in projecting flexible and accurate structured-light patterns onto the object surface to be measured can be obtained. Furthermore, the developed system consists of a specially designed micro-projecting optical unit for generating flexibly optimal structured-light to accommodate requirements in terms of measurement range and resolution. Its wide angle image detection design also improves measurement resolution for detecting deformed fringe patterns. This resolves the problem in capturing effective deformed fringe patterns for phase shifting, especially when a coaxial optical layout of a stereomicroscope is employed. Experimental results verified that the maximum error was within a reasonable range of the measured depth. The developed system and the method can provide a useful and effective tool for 3D full field surface measurement ranging from µm up to cm scale.

scholarly journals Phase Demodulation Method for Fringe Projection Measurement Based on Improved Variable-Frequency Coded Patterns

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4463
Author(s):  
Shanshan Lv ◽  
Mingshun Jiang ◽  
Chenhui Su ◽  
Lei Zhang ◽  
Faye Zhang ◽  
...  
Keyword(s):  
Critical Role ◽  
Three Dimensional ◽  
Surface Profile ◽  
Phase Region ◽  
Fringe Projection ◽  
Measurement Technology ◽  
Variable Frequency ◽  
Profile Measurement ◽  
Imaging Model ◽  
Phase Demodulation

The phase-to-height imaging model, as a three-dimensional (3D) measurement technology, has been commonly applied in fringe projection to assist surface profile measurement, where the efficient and accurate calculation of phase plays a critical role in precise imaging. To deal with multiple extra coded patterns and 2π jump error caused to the existing absolute phase demodulation methods, a novel method of phase demodulation is proposed based on dual variable-frequency (VF) coded patterns. In this paper, the frequency of coded fringe is defined as the number of coded fringes within a single sinusoidal fringe period. First, the effective wrapped phase (EWP) as calculated using the four-step phase shifting method was split into the wrapped phase region with complete period and the wrapped phase region without complete period. Second, the fringe orders in wrapped phase region with complete period were decoded according to the frequency of the VF coded fringes and the continuous characteristic of the fringe order. Notably, the sampling frequency of fast Fourier transform (FFT) was determined by the length of the decoding interval and can be adjusted automatically with the variation in height of the object. Third, the fringe orders in wrapped phase region without complete period were decoded depending on the consistency of fringe orders in the connected region of wrapped phase. Last, phase demodulation was performed. The experimental results were obtained to confirm the effectiveness of the proposed method in the phase demodulation of both discontinuous objects and highly abrupt objects.

Harmonic Analysis on Low Quality Tidal Data

2014 ◽  
Author(s):  
Joost den Haan
Keyword(s):  
Harmonic Analysis ◽  
Three Dimensional ◽  
Measurement Data ◽  
Tidal Energy ◽  
Energy Yield ◽  
Profile Measurement ◽  
Current Profile ◽  
Tidal Power ◽  
Data Set ◽  
Tidal Forcing

The aim of the study is to devise a method to conservatively predict a tidal power generation based on relatively short current profile measurement data sets. Harmonic analysis on a low quality tidal current profile measurement data set only allowed for the reliable estimation of a limited number of constituents leading to a poor prediction of tidal energy yield. Two novel, but very different approaches were taken: firstly a quasi response function is formulated which combines the currents profiles into a single current. Secondly, a three dimensional vectorial tidal forcing model was developed aiming to support the harmonic analysis with upfront knowledge of the actual constituents. The response based approach allowed for a reasonable prediction. The vectorial tidal forcing model proved to be a viable start for a full featuring numerical model; even in its initial simplified form it could provide more insight than the conventional tidal potential models.

An Acoustic System for Pipeline Profile Measurement

1983 ◽  
Vol 105 (4) ◽  
pp. 475-479
Author(s):  
H. Van Calcar
Keyword(s):  
Measurement Technique ◽  
Measurement System ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Profile Measurement ◽  
Baseline Measurement ◽  
Acoustic System ◽  
Position Measurement ◽  
Long Baseline ◽  
Hardware Configuration

This paper presents an acoustic position measurement system used for precise three-dimensional flowline profile measurement. The system measures several points along the flowline using the long-baseline measurement technique and augments this measurement with depth telemetry repeaters to maintain elevation accuracy throughout the changing installation geometry. The paper discusses both the measurement system and the performance enhancement features. The paper concludes with a discussion of the hardware configuration and the accuracy that can be expected when the technique is extended into deeper operating areas.

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