High-fidelity surface reconstruction using complementary colorimetry-encoded fringe projection profilometry.

To solve the challenging issue of uneven reflectance of high-fidelity surface, this paper proposes a three-dimensional (3D) shape measurement method based on surface adaptation complementary colorimetry-encoded fringe projection profilometry. A complete complementary hue extraction method simulates the retina stimulation to establish the complementary conversion relationship between the projected and collected colors of the measurement system. On this basis, a surface reflectance adaptation fringe pattern encoding strategy is proposed to measure the high-fidelity surfaces.

3D shape measurement method for high-reflective surface based on a color camera.

Fringe projection profilometry (FPP) has been widely utilized in many fields due to its non-contact, high accuracy, high resolution and full-field measurement capabilities. However, the limited dynamic range of the camera sensor can result in overexposure of high-reflective parts in industrial production measurement. To effectively solve the above issue, this paper proposes a 3D shape measurement method for the high-reflective surface based on a color camera.

Intelligent Sensing of Thermal Error of CNC Machine Tool Spindle Based on Multi-Source Information Fusion.

Aiming at the shortcomings of single-sensor sensing information characterization ability, which is easily interfered with by external environmental factors, a method of intelligent perception is proposed in this paper. This method integrates multi-source and multi-level information, including spindle temperature field, spindle thermal deformation, operating parameters, and motor current. Firstly, the internal and external thermal-error-related signals of the spindle system are collected by sensors, and the feature parameters are extracted; then, the radial basis function (RBF) neural network is utilized to realize the preliminary integration of the feature parameters because of the advantages of the RBF neural network, which offers strong multi-dimensional solid nonlinear mapping ability and generalization ability.

Multi-view fringe projection profilometry for surfaces with intricate structures and high dynamic range.

Fringe projection profilometry plays an important role for quality control in production line. However, it is facing challenges in the measurement of objects with intricate structures and high dynamic range that involved in precision manufacturing and semiconductor packaging. In this paper, a multi-view fringe projection profilometry system, which deploys a vertical telecentric projector and four oblique tilt-shift cameras, is presented to address the "blind spots" caused by shadowing, occlusion and local specular reflection.

High dynamic range 3D shape measurement based on crosstalk characteristics of a color camera.

Fringe projection profilometry (FPP) has been widely used in many fields due to its fast speed, high accuracy and full-field characteristics. However, it is still a challenging problem to deal with high dynamic range (HDR) objects for traditional FPP, which utilizes a single exposure time or a single projection intensity. Overexposure will occur in areas with large reflectivity, which exceeds the maximum capturing capacity of camera sensors, resulting in the failure to obtain the accurate intensity, absolute phase and three-dimensional (3D) data.

High-accuracy camera calibration method based on coded concentric ring center extraction.

In the field of three-dimensional (3-D) metrology based on fringe projection profilometry (FPP), accurate camera calibration is an essential task and a primary requirement. In order to improve the accuracy of camera calibration, the calibration board or calibration target needs to be manufactured with high accuracy, and the marker points in calibration image require to be positioned with high accuracy. This paper presents an improved camera calibration method by simultaneously optimizing the camera parameters and target geometry.

Three-dimensional reconstruction from a fringe projection system through a planar transparent medium.

A vision measurement system is placed in a protective cover made of a transparent medium to avoid environmental influences. Due to the deflection of light rays on the front and rear surfaces of the transparent medium, the imaging position of an object on the camera target plane is deviated, which makes the traditional vision detection methods based on the triangulation principle produce large measurement errors. This work introduces a three-dimensional (3D) reconstruction method by fringe projection system through a planar transparent medium.

B-spline surface based 3D reconstruction method for deflectometry.

In the field of optical three-dimension (3-D) measurement, reconstruction usually is completed by the integration of a two-dimensional (2-D) gradient data set. Position and posture of camera and shape of the surface under test determine the location of gradient data which usually is on quadrilateral grids. This paper proposes a B-spline surface-based 3D reconstruction method for deflectometry, which reconstructs the surface under test with its 2-D gradient data set.

Stereoscopic deflectometry with a curved screen.

Deflectometry has been widely used in topography measurement of specular surface. In deflectometry with a curved screen, the range of the gradient and height field of the measured specular surface can be effectively expanded compared to deflectometry with a plane screen. As stereo deflectometry measures gradient with high accuracy, the specular surface is reconstructed by integrating the gradient.

Phase Target-Based Calibration of Projector Radial Chromatic Aberration for Color Fringe 3D Measurement Systems.

The camera and projector are indispensable hardware parts of a color fringe projection 3D measurement system. Chromatic aberration between different color channels of the projector and camera has an impact on the measurement accuracy of the color fringe projection 3D profile measurement. There are many studies on camera calibration, but the chromatic aberration of the projector remains a question deserving of further investigation.

A High-Accuracy Calibration Method for a Telecentric Structured Light System.

We propose a method for accurately calibrating a telecentric structured light system consisting of a camera attached to a bilateral telecentric lens and a pin-hole projector. The proposed method can be split into two parts: axial calibration and transverse calibration. The first part is used for building the relationship between phase and depth by means of a planar plate with ring markers on its surface at several different positions in the measuring volume.

Practical Cross-Layer Radio Frequency-Based Authentication Scheme for Internet of Things.

The Internet of Things world is in need of practical solutions for its security. Existing security mechanisms for IoT are mostly not implemented due to complexity, budget, and energy-saving issues. This is especially true for IoT devices that are battery powered, and they should be cost effective to be deployed extensively in the field.

Infrared phase measuring deflectometry by using defocused binary fringe.

Three-dimensional surface information acquisition of specular objects plays an important role in the fields of automobile industry, aerospace, cultural relic protection, intelligent robotics, equipment manufacturing, and so on. Most of the existing specular surface measurement methods are based on focused sinusoidal fringe patterns, so there are certain requirements for the range of the depth of field (DOF) of the camera on the focus position. However, for many specular surfaces with a large gradient, the tested objects may not always be in the DOF of the camera, so sinusoidal fringe patterns are defocused to be vulnerable to the noise.

High-accuracy projector calibration method for fringe projection profilometry considering perspective transformation.

Camera and projector are the key components of structured light three-dimensional (3-D) measurements, and Digital Light Processing (DLP) projector has been widely used for projecting digital structured light patterns for the measurement. The light projecting of projectors can be modeled as the inverse procedures of camera imaging, and its high-accuracy calibration is still a remaining challenge. Therefore, this paper proposes a novel projector calibration method to improve the calibration accuracy of DLP projector.

Monocular Depth Estimation with Joint Attention Feature Distillation and Wavelet-Based Loss Function.

Depth estimation is a crucial component in many 3D vision applications. Monocular depth estimation is gaining increasing interest due to flexible use and extremely low system requirements, but inherently ill-posed and ambiguous characteristics still cause unsatisfactory estimation results. This paper proposes a new deep convolutional neural network for monocular depth estimation.

3D shape measurement of diffused/specular surface by combining fringe projection and direct phase measuring deflectometry.

The three-dimensional (3D) data of object surfaces, like a precision machine part, play an important role in the fields of aerospace, automotive industry, augmented reality, heritage preservation, smart city, etc. The existing fringe projection profilometry and deflectometry can only measure the 3D shape of diffused and specular surfaces, respectively. However, there are many components having both diffused and specular surfaces.

Cost-Effective Wearable Indoor Localization and Motion Analysis via the Integration of UWB and IMU.

Wearable indoor localization can now find applications in a wide spectrum of fields, including the care of children and the elderly, sports motion analysis, rehabilitation medicine, robotics navigation, etc. Conventional inertial measurement unit (IMU)-based position estimation and radio signal indoor localization methods based on WiFi, Bluetooth, ultra-wide band (UWB), and radio frequency identification (RFID) all have their limitations regarding cost, accuracy, or usability, and a combination of the techniques has been considered a promising way to improve the accuracy. This investigation aims to provide a cost-effective wearable sensing solution with data fusion algorithms for indoor localization and real-time motion analysis.

Measurement of the Three-Dimensional Shape of Discontinuous Specular Objects Using Infrared Phase-Measuring Deflectometry.

Phase-measuring deflectometry (PMD)-based methods have been widely used in the measurement of the three-dimensional (3D) shape of specular objects, and the existing PMD methods utilize visible light. However, specular surfaces are sensitive to ambient light. As a result, the reconstructed 3D shape is affected by the external environment in actual measurements.

Radio Frequency Identification and Sensing Techniques and Their Applications-A Review of the State-of-the-Art.

Radio Frequency Identification (RFID) sensors, integrating the features of Wireless Information and Power Transfer (WIPT), object identification and energy efficient sensing capabilities, have been considered a new paradigm of sensing and communication for the futuristic information systems. RFID sensor tags featuring contactless sensing, wireless information transfer, wireless powered, light weight, non-line-of-sight transmission, flexible and pasteable are a critical enabling technology for future Internet-of-Things (IoT) applications, such as manufacturing, logistics, healthcare, agriculture and food. They have attracted numerous research efforts due to their innovative potential in the various application fields.

Calibration of the Relative Orientation between Multiple Depth Cameras Based on a Three-Dimensional Target.

Depth cameras play a vital role in three-dimensional (3D) shape reconstruction, machine vision, augmented/virtual reality and other visual information-related fields. However, a single depth camera cannot obtain complete information about an object by itself due to the limitation of the camera's field of view. Multiple depth cameras can solve this problem by acquiring depth information from different viewpoints.

Single-shot 3D shape measurement of discontinuous objects based on a coaxial fringe projection system.

Fringe projection profilometry has been widely used in high-speed three-dimensional (3D) shape measurement. To improve the speed without loss of accuracy, we present a novel single-shot 3D shape measuring system that utilizes a coaxial fringe projection system and a 2CCD camera. The coaxial fringe projection system, comprising a visible light (red, green, and blue) projector and an infrared (IR) light projector, can simultaneously project red, green, blue, and IR fringe patterns.

Discovery of new quinazoline derivatives as irreversible dual EGFR/HER2 inhibitors and their anticancer activities - Part 1.

Overexpression of EGFR and HER2 are observed in many breast, ovarian, colon and prostate cancers. The second and third generation irreversible EGFR/HER2 dual kinase inhibitors became popular after the approval of Afatinib by FDA to overcome the mutation related problem. To find efficacious drug candidates, a series of novel quinazoline derivatives were designed, synthesized and evaluated as dual EGFR/HER2 tyrosine kinase (TK) inhibitors.

3D shape measurement of discontinuous specular objects based on advanced PMD with bi-telecentric lens.

This paper presents an advanced phase measuring deflectometry (PMD) method based on a novel mathematical model to obtain three dimensional (3D) shape of discontinuous specular object using a bi-telecentric lens. The proposed method uses an LCD screen, a flat beam splitter, a camera with a bi-telecentric lens, and a translating stage. The LCD screen is used to display sinusoidal fringe patterns and can be moved by the stage to two different positions along the normal direction of a reference plane.

Distance Calibration between Reference Plane and Screen in Direct Phase Measuring Deflectometry.

The recently developed direct phase measuring deflectometry (DPMD) method can directly measure the three-dimensional (3D) shape of specular objects with discontinuous surfaces, but requires a calibrated distance between a reference plane and liquid crystal display screen. Because the plane and screen are different distances from the imaging device, they cannot be clearly captured given the limited depth of field (DOF) of the lens. Therefore, existing machine vision-based methods cannot be used to effectively calibrate a DPMD system.