3D Measurement Method Research Articles

In vivo three-dimensional mandibular kinematics and functional point trajectories during temporomandibular activities using 3d fluoroscopy.

To measure in vivo three-dimensional kinematics of the mandible and associated end-point trajectories and to quantify their relationships during temporomandibular joint activities using 3D fluoroscopy. A novel fluoroscopy-based 3D measurement method was used to measure motions of the mandible and the associated end points (i.e. incisors and lateral poles of both condyles) during open close, lateral gliding and protrusion-retraction movements in healthy young individuals. The contributions of each of the rotational and translational components of the mandible to the end-point trajectories were quantified through experiment-based computer simulations. The mandibular rotation was found to account for 91% of the maximal mouth-opening-capacity and 73% of the maximal lateral incisor movement, while the condylar translation contributed to 99% of the anterior protrusion distance. Incisor trajectories were nearly vertical within the first 60% of the maximal opening during the open-close movement. Similar condylar downward rotation paths but with bilaterally asymmetrical ranges were used to perform basic mandibular movements of different targeted TI trajectories in three dimensions, that is, open-close, lateral-gliding and protrusion-retraction. Mandibular rotations contributed to the majority of the principal displacement components of the incisor, that is, vertical during open-close and towards the working-side-during lateral-gliding, while mandibular translation contributed mainly to the forward movement of the incisor during protrusion-retraction. Owing to the anatomical constraints, the freedom of mandibular translation is limited and mainly in the anteroposterior direction, which is considered helpful for the control and stability of the TMJ during oral activities.

The impact of limb loading and the measurement modality (2D versus 3D) on the measurement of the limb loading dependent lower extremity parameters

BackgroundDeformity assessment and preoperative planning of realignment surgery are conventionally based on weight-bearing (WB) radiographs. However, newer technologies such as three-dimensional (3D) preoperative planning and surgical navigation with patient-specific instruments (PSI) rely on non-weight bearing (NWB) computed tomography (CT) data. Additionally, differences between conventional two-dimensional (2D) and 3D measurements are known. The goal of the present study was to systematically analyse the influence of WB and the measurement modality (2D versus 3D) on common WB-dependent measurements used for deformity assessment.Methods85 lower limbs could be included. Two readers measured the hip-knee-ankle angle (HKA) and the joint line convergence angle (JLCA) in 2D WB and 2D NWB radiographs, as well as in CT-reconstructed 3D models using an already established 3D measurement method for HKA, and a newly developed 3D measurement method for JLCA, respectively. Interrater and intermodality reliability was assessed.ResultsSignificant differences between WB and NWB measurements were found for HKA (p < 0.001) and JLCA (p < 0.001). No significant difference could be observed between 2D HKA NWB and 3D HKA (p = 0.09). The difference between 2D JLCA NWB and 3D JLCA was significant (p < 0.001). The intraclass correlation coefficient (ICC) for the interrater agreement was almost perfect for all HKA and 3D JLCA measurements and substantial for 2D JLCA WB and 2D JLCA NWB. ICC for the intermodality agreement was almost perfect between 2D HKA WB and 2D HKA NWB as well as between 2D HKA NWB and 3D HKA, whereas it was moderate between 2D JLCA WB and 2D JLCA NWB and between 2D JLCA NWB and 3D JLCA.ConclusionLimb loading results in significant differences for both HKA and JLCA measurements. Furthermore, 2D projections were found to be insufficient to represent 3D joint anatomy in complex cases. With an increasing number of surgical approaches based on NWB CT-reconstructed models, research should focus on the development of 3D planning methods that consider the effects of WB on leg alignment.

High-speed high dynamic range 3D shape measurement based on deep learning

For many three-dimensional (3D) measurement techniques based on fringe projection profilometry (FPP), measuring the objects with a large variation range of surface reflectivity is always a very tricky problem due to the limited dynamic range of camera. Many high dynamic range (HDR) 3D measurement methods are developed for static scenes, which are fragile for dynamic objects. In this paper, we address the problem of phase information loss in HDR scenes, in order to enable 3D reconstruction from saturated or dark images by deep learning. By using a specifically designed convolutional neural network (CNN), we can accurately extract phase information in both the low signal-to-noise ratio (SNR) and saturation situations after proper training. Experimental results demonstrate the success of our network in 3D reconstruction for both static and dynamic HDR objects. Our method can improve the dynamic range of three-step phase-shifting by a factor of 4.8 without any additional projected images or hardware adjustment during measurement. And the final 3D measurement speed of our method is about 13.89 Hz (off-line).

3D Topography Measurement and Completion Method of Blast Furnace Burden Surface Using High-Temperature Industrial Endoscope

Accurate and real-time 3D burden surface topography of a blast furnace plays an important role in improving the gas flow distribution and optimizing the charging operation, and therefore has great potential to reduce both its CO2 emissions and energy consumption. However, because of the high-temperature, dusty and dark environment inside the furnace, as well as limitations in terms of installation position and viewing angle of the image capturing equipment, it is difficult to obtain clear, continuous and complete images of the burden surface and reconstruct accurate 3D topography in real time. To overcome these limitations, a novel 3D topography measurement and completion method of the burden surface is proposed in this study. First, a high-temperature industrial endoscope is designed and installed to capture the burden surface images during the blast furnace ironmaking process. Then, the details of the burden surface images are enhanced using image sharpening methods and the regions of interest of the images are extracted based on texture energy features. Next, a method based on the depth from defocus is used to calculate the depth of burden surface. Finally, considering that most of the images are incomplete because of the limitations above, a new 3D completion model is established to complete the burden surface topography based on a variational auto encoder and a generative adversarial network. On-site experiments and their validation demonstrate that the proposed method can obtain complete and accurate 3D burden surface topography and provide highly reliable topography data to optimize blast furnace operations.

A novel high dynamic range 3D measurement method based on adaptive fringe projection technique

Fringe projection techniques have been widely used in three-dimensional (3D) small-field measurement; however, measuring the 3D shapes of small objects with high ranges of reflectivity across their surfaces remains challenging because image saturation leads to measurement error. In this study, a novel adaptive fringe projection technique was proposed to address this issue. First, a 255 uniform gray-level pattern was projected onto the surface to mark the saturated region in the captured image. Second, another uniform gray-level pattern with lower intensity was used to calculate the reflectivity across the surface and an appropriate projection gray level in the camera coordinate system was calculated at the pixel level. Third, a set of orthogonal sinusoidal fringe patterns were projected onto the object to establish the spatial relationship between the camera and projection systems, and adaptive fringe patterns were generated in the projection coordinate system. Subsequently, the generated adaptive fringe patterns were used to measure the object. The experimental results demonstrate that the proposed method could retrieve the 3D shapes of small shiny objects with high accuracy and relatively few images.

New developments on EDR (Event Data Recorder) for automated vehicles

AbstractWith the upcoming new legislative rules in the EU on Event Data Recorder beginning 2022 the question is whether the discussed data base is sufficient for the needs of clarifying accidents involving automated vehicles. Based on the reconstruction of real accidents including vehicles with ADAS combined with specially designed crash tests a broader data base than US EDR regulation (NHTSA 49 CFR Part 563.7) is proposed. The working group AHEAD, to which the authors contribute, has already elaborated a data model that fits the needs of automated driving. The structure of this data model is shown. Moreover, the special benefits of storing internal video or photo feeds form the vehicle camera systems combined with object data is illustrated. When using a sophisticate 3D measurement method of the accident scene the videos or photos can also serve as a control instance for the stored vehicle data. The AHEAD Data Model enhanced with the storage of the video and photo feeds should be considered in the planned roadmap of the Informal Working Group (IWG) on EDR/ DSSAD (Data Storage System for Automated Driving) reporting to UNECE WP29. Also, a data access over the air using technology already applied in China for electric vehicles called Real Time Monitoring would allow a quantum leap in forensic accident reconstruction.

자동 비파괴검사 구현을 위한 3차원 형상 측정 및 경로 설계 방법

자동 비파괴검사 구현을 위한 3차원 형상 측정 및 경로 설계 방법

Polarized-state-based coding strategy and phase image estimation method for robust 3D measurement.

Polarized structured light is a novel method to measure shiny surface. However, the SNR of the captured image was affected by the additional polarizing filter. And the blurred influence of camera defocus was also strengthened. The accuracy of fringe edges detection was reduced. In this paper, a polarized-state-based structured light coding strategy and a phase image estimation method are proposed to improve the measurement robustness. To preserve the coding message in the complex environment, a special polarized-state-based coding strategy is adopted. To reduce the error which induced by additional polarizing filter and extracting the information from the saturated areas as much as possible, a phase image estimation method based on Stokes parameter is proposed. Compared with the traditional polarization-based structured light system, the experimental setup of proposed method is configured without any additional hardware. The experiment shows that the interference of camera defocus is remarkably reduced and the robustness of fringe edges detection is improved.

Strain Analysis on Electrochemical Failures of Nanoscale Silicon Electrode Based on Three-Dimensional In Situ Measurement

Nanoscale silicon film electrodes in Li-ion battery undergo great deformations leading to electrochemical and mechanical failures during repeated charging-discharging cycles. In-situ experimental characterization of the stress/strain in those electrodes still faces big challenges due to remarkable complexity of stress/strain evolution while it is still hard to predict the association between the electrode cycle life and the measurable mechanical parameters. To quantificationally investigate the evolution of the mechanical parameters, we develop a new full field 3D measurement method combining digital image correlation with laser confocal profilometry and propose a strain criterion of the failure based on semi-quantitative analysis via mean strain gradient (MSG). The experimental protocol and results illustrate that the revolution of MSG correlates positively with battery capacity decay, which may inspire future studies in the field of film electrodes.

Quantitative Evaluation of Articular Involvement of Posterior Malleolus Associated with Operative Indication: A Comparative Study of Six Methods Based on Radiography and CT

The aim of this study was to compare the values of six methods in measuring the involvement of posterior malleolus and to demonstrate the reliability and reproducibility of each method. Three independent orthopaedic surgeons, retrospectively, measured 106 cases. The difference between the six methods was analyzed using Bonferroni-corrected paired t-tests after one-way ANOVA. The agreement between the six methods was analyzed using Bland–Altman analysis. The intraclass correlation coefficient (ICC) was used to assess intraobserver reproducibility and interobserver reliability. Significant differences were observed between values of any two of the six measurement methods (P < 0.0033), except between any two of the plane radiograph linear, axial CT linear, sagittal CT linear, and 3D CT linear. The Bland–Altman plots demonstrated poor agreement between values of any two of the six methods. The lowest intraobserver reproducibility was 0.46 (moderate) for resident surgeon using plain radiographs. The intraobserver reproducibility for three surgeons using two-dimensional (2D) and 3D images was almost perfect (ICC, 0.82–0.96). The lowest interobserver reliability was 0.41 (moderate) between chief and attending surgeon using plain radiographs, and it improved to almost perfect (ICC, 0.81–0.95) with the use of 3D CT images. The standard error of measurement showed almost the same results as ICC values. The existing operative indications which were determined based on plain radiography are neither reliable nor suitable for other measurement methods. Both 3D linear and 3D surface measurement methods are reliable and reproducible in measuring posterior fragment involvement, and experience is not so crucial. Operative indications for posterior malleolar fractures need to be redefined based on the 3D measurement method.

基于水面特征波纹的潜艇多波段光电偏振成像探测性仿真研究

Submarine detection is a key technology of coastline defense, the direct and indirect imaging to detect submarines both involves solving the problem of detecting the water surface ripple. 3D surface measurement method based on polarization detection can effectively detect the water corrugated surface, in which the detection and calculation of surface polarization characteristics is an important part of surface reconstruction. The model of water surface polarization was established. Visible and infrared waveband of the water polarization characteristic under different water temperature, different meteorological conditions were simulated and analyzed. The results show that the surface polarization is s polarization in the visible waveband and p polarization in the middle and long infrared waveband, degree of polarization first increases with the increase of incident angle and then decreases, moreover the degree of water surface polarization increases with the rising of temperature. The degree of water surface polarization in visible, middle infrared and long infrared waveband was measured by polarization measurement system based on Stokes vector. The results of the simulation were consistent with the measured results, which proved the accuracy of the polarization model used. The characteristics of polarization imaging detection in common wavebands were analyzed, which can provide theoretical simulation and experimental methods for the analysis and calculation of polarization characteristics of water surface.

Development of tactile sensor using stereo fisheye camera by rotation

In this paper, we propose a 3D coordinate measurement method using a stereo fisheye camera using rotation for tactile sensors.A soft haptic interface by an optical method using a camera has simple wiring and the like, and has a point that it does not impair the mechanical properties of a flexible outer skin and is strong against noise. On the other hand, since many ranges inside the sensor are used for sensing, there is a disadvantage that the usable range inside is narrow. In this paper, we propose a three-dimensional coordinate estimation method using the rotation of a fish-eye camera to expand the usable range inside the tactile sensor. Experimental results show the effectiveness of the proposed method.

Three-dimensional mandibular motion trajectory-tracking system based on BP neural network.

The aim of this study was to develop a prototype three-dimensional optical motion capture system based on binocular stereo vision, Back-propagation (BP) Neural Network and 3D compen-sation method for accurate and real-time recording of mandibular movement. A specialized 3D method of compensation to eliminate the involuntary vibration motions by human heart beating and respiration. A kind of binocular visual 3D measurement method based on projection line and a calibration method based on BP neural network is proposed to solve the problem of the high complexity of camera calibration process and the low accuracy of 3D measurement. The accuracy of the proposed system is systematically evaluated by means of electric platform and clinical trials, and the root-mean-square is 0.0773 mm. Finally, comparisons with state-of-the-art methods demonstrate that our system has higher reliability and accuracy. Meanwhile, the motion trajectory-tracking system is expected to be used in the diagnosis of clinical oral diseases and digital design of restoration.

多阶段深度学习单帧条纹投影三维测量方法

多阶段深度学习单帧条纹投影三维测量方法

多阶段深度学习单帧条纹投影三维测量方法

多阶段深度学习单帧条纹投影三维测量方法

A 3D measurement method for specular surfaces based on polarization image sequences and machine learning

Image highlights caused by specular reflections always conceal or attenuate the feature information of the samples in vision measurement. This paper investigates countermeasures to highlighted specular surface measurements. A measurement system is developed to capture a series of images with different polarization angles, the highlighted regions of which are taken as the trained samples for a back-propagation neural network, while the initial weights of the neural network are set as Gaussian distributions. Experimental results show that the proposed method can efficiently increase the stereo matching accuracy and hence recover the information in highlighted regions in vision measurements of specular surfaces.

Three-Dimensional Morphological Measurement Method for a Fruit Tree Canopy Based on Kinect Sensor Self-Calibration

Perception of the fruit tree canopy is a vital technology for the intelligent control of a modern standardized orchard. Due to the complex three-dimensional (3D) structure of the fruit tree canopy, morphological parameters extracted from two-dimensional (2D) or single-perspective 3D images are not comprehensive enough. Three-dimensional information from different perspectives must be combined in order to perceive the canopy information efficiently and accurately in complex orchard field environment. The algorithms used for the registration and fusion of data from different perspectives and the subsequent extraction of fruit tree canopy related parameters are the keys to the problem. This study proposed a 3D morphological measurement method for a fruit tree canopy based on Kinect sensor self-calibration, including 3D point cloud generation, point cloud registration and canopy information extraction of apple tree canopy. Using 32 apple trees (Yanfu 3 variety) morphological parameters of the height (H), maximum canopy width (W) and canopy thickness (D) were calculated. The accuracy and applicability of this method for extraction of morphological parameters were statistically analyzed. The results showed that, on both sides of the fruit trees, the average relative error (ARE) values of the morphological parameters including the fruit tree height (H), maximum tree width (W) and canopy thickness (D) between the calculated values and measured values were 3.8%, 12.7% and 5.0%, respectively, under the V1 mode; the ARE values under the V2 mode were 3.3%, 9.5% and 4.9%, respectively; and the ARE values under the V1 and V2 merged mode were 2.5%, 3.6% and 3.2%, respectively. The measurement accuracy of the tree width (W) under the double visual angle mode had a significant advantage over that under the single visual angle mode. The 3D point cloud reconstruction method based on Kinect self-calibration proposed in this study has high precision and stable performance, and the auxiliary calibration objects are readily portable and easy to install. It can be applied to different experimental scenes to extract 3D information of fruit tree canopies and has important implications to achieve the intelligent control of standardized orchards.

3D shape measurement of translucent objects based on Fourier single-pixel imaging in projector-camera system.

3D shape measurement by structured light is a popular technique for recovering object surfaces. However, structured light technique assumes that scene points are directly illuminated by the light source(s). Consequently, global illumination effects, such as subsurface scattering in translucent objects, may cause measurement errors in recovered 3D shapes. In this research, we propose a 3D shape measurement method of translucent objects based on Fourier single-pixel imaging (FSI) technique. The 3D shapes of the translucent objects are reconstructed through stereo matching of direct illumination light, which is separated from the surface. Experimental results show that the proposed method can separate the direct illumination light and the subsurface scattering light. The feasibility and accuracy of the method are analyzed, and the qualitative and quantitative results of the method are provided.

Three-Dimensional Measurement Method of Four-View Stereo Vision Based on Gaussian Process Regression

Multisensor systems can overcome the limitation of measurement range of single-sensor systems, but often require complex calibration and data fusion. In this study, a three-dimensional (3D) measurement method of four-view stereo vision based on Gaussian process (GP) regression is proposed. Two sets of point cloud data of the measured object are obtained by gray-code phase-shifting technique. On the basis of the characteristics of the measured object, specific composite kernel functions are designed to obtain the initial GP model. In view of the difference of noise in each group of point cloud data, the weight idea is introduced to optimize the GP model, which is the data fusion based on Bayesian inference method for point cloud data. The proposed method does not require strict hardware constraints. Simulations for the curve and the high-order surface and experiments of complex 3D objects have been designed to compare the reconstructing accuracy of the proposed method and the traditional methods. The results show that the proposed method is superior to the traditional methods in measurement accuracy and reconstruction effect.

Effect of the fuel-air flow velocity on heat release rate of swirling non-premixed methane flames

A laboratory-scale gas turbine model combustor fueled with methane is studied experimentally with the aid of three-dimensional computed tomography of chemiluminescence (3D-CTC) and high speed (5 kHz) chemiluminescence imaging. Various fuel-lean operating conditions were tested to investigate the impact of flow velocity on heat release rate oscillation and spatial structure transition with fixed global equivalence ratio of about 0.65 and dump plane velocity of 2.9–18.3 m/s. In the study of combustion structure transition, the three-dimensional relative emissions of CH* were measured and taken as qualitative indicators of the heat release rate. This 3D measurement method utilizes CH* images from 8 directional as inputs combined with tomographic algorithms to compute the 3D distribution of CH* CL intensities. For all tested conditions, pronounced extension of inner recirculation zone (IRZ) along the nozzle is observed under the attached (V-shaped) swirl stabilized flames. During the increase of Reynolds number, the heat release zone changing obviously along the nozzle radial and axis direction, and the largest heat release plane moves downstream significantly. In addition, an intensified high-speed camera was adopted for the heat release dynamics study. Strong oscillations appeared in the flame zone that significantly affected the total heat release oscillations, and oscillation increases with the raise of Reynolds number.