System geometrical calibration is a challenging task in fringe-reflection 3D measurement because the fringe displayed on LCD screen does not lie within camera's field of view. Commonly, flat mirror with markers can accomplish system calibration. However, position must be precisely located by photogrammetry advance. In this Letter, we introduce method use markerless mirror. Experiments phase measuring deflectometry demonstrate that proposed simple and flexible.

An improved optical geometry of the projected-fringe profilometry technique, in which exit pupil projecting lens and entrance imaging are neither at same height above reference plane nor coplanar, is discussed used Fourier-transform profilometry. Furthermore, an fringe-pattern description phase-height mapping formula based on geometrical generalization deduced. Employing new geometry, it easier for us to obtain full-field fringe by moving either projector or device. Therefore method offers a...

Three-dimensional (3D) shape measurement of an aspheric mirror with fringe reflection photogrammetry involves three steps: correspondence matching, triangulation, and bundle adjustment. Correspondence matching is realized by absolute phase tracking triangulation computed the intersection incidence rays. The main contribution in this paper constraint adjustment for carefully dealing lens distortion process ray intersection, as compared to well-known grating photogrammetry. Additionally, a...

Cyclodextrins (CDs), a low-polysaccharide class, possess hydrophilic outer surface due to their hydroxyl groups, which can be functionalized for various applications. In this study, the groups on β-cyclodextrin were with acrylates (CD-A) and subsequently used as cross-linker in copolymerization acrylamide form polyacrylamide-cyclodextrin hydrogel (PAC). Compared polyacrylamide (PAM), PAC exhibited enhanced water absorption abilities mechanical strength. Inspired by fish scales' structural...

The phase unwrapping algorithm plays a very important role in many noncontact optical profilometries based on triangular measurement theory. Here we focus discussing how to diminish the error caused by incorrect path wavelet transform profilometry. We employ amplitude value map of coefficients at wavelet-ridge position identify reliability data and unwrapping. This means that wrapped located pixel with highest will be selected as starting point unwrapping, pixels higher unwrapped earlier. So...

Empirical mode decomposition is introduced into Fourier transform profilometry to extract the zero spectrum included in deformed fringe pattern without need for capturing two patterns with π phase difference. The subsequently demodulated using a standard algorithm. With this method, adaptively decomposed finite number of intrinsic functions that vary from high frequency low by means an algorithm referred as sifting process. Then separated high-frequency components effectively. Experiments...

High-frequency oscillations (HFOs) of 80~500 Hz in the intracranial electroencephalogram (iEEG) recordings are considered as a reliable marker for epileptic location. However, significant challenge to clinical use HFOs is due time-consuming procedure visually identifying them. A new methodology presented this paper automated detection based on their 2D time-frequency map employing short-time energy (STE) estimation and convolutional neural network (CNN) classification algorithm. The...

Wavelet ridge techniques utilizing daughter wavelets under two different kinds of definitions in the optical fringe pattern analysis are theoretically clarified. The clarification reveals that phase is equal to its wavelet transform coefficients on using both definitions. differences between performance algorithms verified theory. strict relations instantaneous frequency and scale parameter at position also clarified for gradient method. A simple method selecting vector introduced. Computer...

To determine the shape of a complex object with vertical measurement mode and higher accuracy, novel modulation measuring profilometry realizing auto-synchronous phase shifting scanning is proposed. Coaxial optical system for projection observation instead triangulation adopted to avoid shadow occlusion. In projecting system, sinusoidal grating perpendicular axis. For moving along direction at certain angle axis, 1D precision translation platform applied achieve purposes both phase-shifting...

A two-dimensional continuous wavelet transform employing a real mother is applied to phase analysis of spatial carrier fringe patterns. In this method, Hilbert first performed on pattern get an analytic signal. Then calculated for the signal that yielded by transform. Finally, height-demodulated information can be gotten from coefficients at ridge position. The performance proposed method has been evaluated using computer-generated and result better than one-dimensional algorithms in area...

Establishing a highly accurate phase-to-height mapping relationship is very important in fringe projection profilometry, which guarantees the accuracy of final three-dimensional reconstruction. The influence coming from lens distortion, random noises, and nontelecentric projecting imaging measurement system analyzed detail, followed by exhaustive discussion more method. tabulation between absolute phase height information set up piecewise linear fitting method within whole range for...

In this Letter, the periodical errors, which are caused by nonlinear effect of commercial projector and camera, analyzed as a more generic single-coefficient model. The probability density function wrapped phase distributions is used tool to find compensation coefficient. When coefficient detected, on premise ensuring accuracy, correlation algorithm process replace traditional iterative process. Therefore, proposed improves efficiency detection dramatically. Both computer simulation...

In this paper, a fast rotary mechanical projector (RMP) is designed and manufactured for high-speed 3D shape measurement. Compared with the common projectors, RMP has good performance in projection, which can obtain high quality projected fringes shorter camera exposure time by using error diffusion binary coding method chrome plating technology. The magnitude, acceptability of systemic projection analyzed quantified detail. For error, probability distribution function (PDF) algorithm...

This paper presents a method for camera calibration based on the orthogonal vanishing point using concentric circles grating and wedge grating. method, which we believe is new, uses high-precision characteristics of phase extraction to obtain feature points, thus decreasing errors caused by traditional marker gray pattern. According simulation experiment analysis results, was designed with seven periods four periods. In real measuring experiment, target similar were used calibrate camera,...