A Dynamic Position Measurement Method for Destructive Process of Structures Using Image Processing

2004 ◽  
Author(s):  
Hiroshi Nishizawa ◽  
Satoshi Fujita ◽  
Osamu Furuya
Keyword(s):  
Image Processing ◽  
High Precision ◽  
High Speed ◽  
Spherical Surface ◽  
Three Dimensional ◽  
Measuring System ◽  
Position Measurement ◽  
Surface Emission ◽  
Optical Motion ◽  
Optical Motion Capture

In order to clarify the destruction mechanism of large structures in large seismic movements, a non-contacting displacement measurement system with a three-dimensional dynamic position with high precision is required. We have developed a three-dimensional measuring system with image processing using optical motion capture technology. This system consists of light emitting markers installed on the object structure and plural high speed cameras which obtain images of markers’ movement simultaneously, to measure the dynamic position of the three dimensional spatial coordinates of the markers. In order to measure the dynamic position with high precision, we have ever developed sub-pixel processing method which is able to measure very small displacements of the markers by analyzing the luminance distribution. Moreover, we have developed a new marker of spherical surface emission type which formed the luminance profile to improve furthermore the accuracy in rotational movement. Shaking tests were carried out with this measuring system and the results indicated that this system using new markers had sufficient accuracy within errors of a few millimeters in the structure of a 4 meter cube. Consequently, we have acquired the potential to apply to the measurement to the 3-D Full Scale Earthquake Testing Facility (E-Defense).

Absolute Measurement of Aspheric Surfaces Using White-Light Interferometry

2007 ◽  
Vol 364-366 ◽  
pp. 80-85
Author(s):  
Su Ping Chang ◽  
Tie Bang Xie ◽  
Xuang Ze Wang ◽  
Jun Guo
Keyword(s):  
High Precision ◽  
White Light ◽  
Spherical Surface ◽  
Three Dimensional ◽  
Influence Factors ◽  
Horizontal Displacement ◽  
Absolute Measurement ◽  
Aspheric Surfaces ◽  
Interferometric Technique ◽  
Main Influence

White-light interferometric technique has been widely applied in the measurement of three-dimensional profiles and roughness with high-precision. Based on the characteristic of interferometric technique, a new method combined with image location and a three-dimensional stage is proposed to achieve the non-contact absolute shape measurement for aspheric and spherical surface in a slarge range. The interference fringes vary with the horizontal displacement of the measured surface, the surface information was obtained by locating the transformation of the maximal intensity in the interferograms. Two main influence factors are discussed; they are performance of the inerferimetric microscope and the stage. Since the performance of the stage directly determines the measurement precision, a three-dimensional displacement stage with a large range and a high precision was developed. Some experiments were carried out to verify the performance of the three-dimensional displacement stage and the validity of the new measurement method with satisfactory results.

Human Motion Capture Driven by Orientation Measurements

1999 ◽  
Vol 8 (2) ◽  
pp. 187-203 ◽  
Author(s):  
Tom Molet ◽  
Ronan Boulic ◽  
Daniel Thalmann
Keyword(s):  
Motion Capture ◽  
Human Motion ◽  
High Rate ◽  
Position Measurement ◽  
Human Motion Capture ◽  
Fast Tracking ◽  
Optical Motion ◽  
Optical Motion Capture ◽  
Tracking Object ◽  
Capture Techniques

Motion-capture techniques are rarely based on orientation measurements for two main reasons: (1) optical motion-capture systems are designed for tracking object position rather than their orientation (which can be deduced from several trackers), (2) known animation techniques, like inverse kinematics or geometric algorithms, require position targets constantly, but orientation inputs only occasionally. We propose a complete human motion-capture technique based essentially on orientation measurements. The position measurement is used only for recovering the global position of the performer. This method allows fast tracking of human gestures for interactive applications as well as high rate recording. Several motion-capture optimizations, including the multijoint technique, improve the posture realism. This work is well suited for magnetic-based systems that rely more on orientation registration (in our environment) than position measurements that necessitate difficult system calibration.

Development of a noncontact liquid level measuring system using image processing

1998 ◽  
Vol 37 (12) ◽  
pp. 381-387 ◽  
Author(s):  
Yoichi Takagi ◽  
Akio Tsujikawa ◽  
Masao Takato ◽  
Takeshi Saito ◽  
Motoko Kaida
Keyword(s):  
Image Processing ◽  
High Precision ◽  
Inflection Point ◽  
Liquid Surface ◽  
Metal Strip ◽  
Liquid Level ◽  
Alcoholic Beverages ◽  
Measuring System ◽  
Single Image ◽  
Monitor Screen

This paper describes how the authors developed a liquid level measuring system designed to directly analyze images of liquid surfaces. This measuring system is based on the principle that the contour of the image of a slanted metal strip placed in a liquid shows an inflection point on the liquid interface. This liquid level measuring system using image processing is useful in automatically measuring the levels of water, oil, liquefied gases, and alcoholic beverages. Among the features of this measuring system are: (1) it is of the noncontact type, so that there is no need to install a sensor or other high-precision devices close to the liquid to be measured; (2) it can be installed in a way not affected by the liquid; (3) the scale and the liquid surface can be analyzed on an image basis directly, so that periodic recalibration is unnecessary; (4) deviations in measurements can be easily detected by visually checking the monitor screen; (5) images from more than one camera can be processed with a single image processor to reduce total costs.

scholarly journals Accuracy Assessment for the Three-Dimensional Coordinates by High-Speed Videogrammetric Measurement

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Xianglei Liu ◽  
Yi Tang ◽  
Jing Ma
Keyword(s):  
High Speed ◽  
Accuracy Assessment ◽  
Three Dimensional ◽  
Shaking Table ◽  
Measuring System ◽  
Accuracy Analysis ◽  
Alternative Technique ◽  
Cmos Camera ◽  
Spatial Coordinates ◽  
Three Dimensional Coordinate

High-speed CMOS camera is a new kind of transducer to make the videogrammetric measurement for monitoring the displacement of high-speed shaking table structure. The purpose of this paper is to validate the three-dimensional coordinate accuracy of the shaking table structure acquired from the presented high-speed videogrammetric measuring system. In the paper, all of the key intermediate links are discussed, including the high-speed CMOS videogrammetric measurement system, the layout of the control network, the elliptical target detection, and the accuracy validation of final 3D spatial results. Through the accuracy analysis, the submillimeter accuracy can be made for the final the three-dimensional spatial coordinates which certify that the proposed high-speed videogrammetric technique is a better alternative technique which can replace the traditional transducer technique for monitoring the dynamic response for the shaking table structure.

scholarly journals Comparison of modelling and tracking methods for analysing elbow and forearm kinematics

2019 ◽  
Vol 233 (11) ◽  
pp. 1113-1121 ◽  
Author(s):  
Wei Wang ◽  
Dongmei Wang ◽  
Mariska Wesseling ◽  
Bin Xue ◽  
Feiyue Li
Keyword(s):  
Three Dimensional ◽  
Optimal Estimation ◽  
Elbow Flexion ◽  
Coordinate Systems ◽  
Kinematic Data ◽  
Measurement Protocol ◽  
Flexion Extension ◽  
Good Consistency ◽  
Optical Motion ◽  
Optical Motion Capture

This study aimed to find an optimal measurement protocol of elbow and forearm kinematics using different modelling and tracking methods. Kinematic data of elbow flexion/extension and forearm pronation/supination was acquired using optical motion capture from 12 healthy male volunteers. Segment coordinate systems for humerus, forearm, radius, ulna, and hand were defined. Different tracking methods, using anatomical markers or rigid or point maker clusters, were used to compute the three-dimensional rotations. Marker placement errors were assessed to evaluate the rigid body assumption. Multiple comparisons demonstrated statistical differences between tracking methods: compared to using only anatomical markers, tracking using clusters reduced the estimated range of pronation/supination by 14.9%–43.2%, while it estimated increased flexion/extension by 5.3%–9.1%. The study suggests using only anatomical markers exerts the optimal estimation of elbow and forearm kinematics. Modelling using the coordinate systems of the humerus and forearm and of the humerus and ulna, respectively, demonstrated good consistency with literature and are correspondingly regarded as the most appropriate approach for measuring pronation/supination and flexion/extension. The results are valuable in establishing a measurement protocol for analysing elbow and forearm kinematics, avoiding confusions and misinterpretations in communicating results from different methodologies.

scholarly journals An Automated Three-Dimensional Bone Pose Tracking Method Using Clinical Interleaved Biplane Fluoroscopy Systems: Application to the Knee

2020 ◽  
Vol 10 (23) ◽  
pp. 8426
Author(s):  
Cheng-Chung Lin ◽  
Tung-Wu Lu ◽  
Jia-Da Li ◽  
Mei-Ying Kuo ◽  
Chien-Chun Kuo ◽  
...  
Keyword(s):  
Imaging System ◽  
Three Dimensional ◽  
Pose Tracking ◽  
Model Based ◽  
X Ray Imaging ◽  
Custom Made ◽  
Optical Motion ◽  
Optical Motion Capture ◽  
Tibiofemoral Kinematics ◽  
Biplane Fluoroscopy

Model-based tracking of the movement of the tibiofemoral joint via a biplane X-ray imaging system has been commonly used to reproduce its accurate, three-dimensional kinematics. To accommodate the approaches to existing clinical asynchronous biplane fluoroscopy systems and achieve comparable accuracy, this study proposed an automated model-based interleaved biplane fluoroscopy image tracking scheme (MIBFT) by incorporating information of adjacent image frames. The MIBFT was evaluated with a cadaveric study conducted on a knee specimen. The MIBFT reproduced skeletal poses and tibiofemoral kinematics that were in good agreement with the standard reference kinematics provided by an optical motion capture system, in which the root-mean-squared (Rms) errors of the skeletal pose parameters ranged from 0.11 to 0.35 mm in translation and 0.18 to 0.49° in rotation. The influences of rotation speed on the pose errors were below 0.23 mm and 0.26°. The MIBFT-determined bias, precision, and Rms error were comparable to those of the reported model-based tracking techniques using custom-made synchronous biplane fluoroscopy. The results suggested that the further use of the clinical imaging system is feasible for the noninvasive and precise examination of dynamic joint functions and kinematics in clinical practice and biomechanical research.

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