Results 211 to 220 of about 189,557 (261)
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Three‐dimensional measurement accuracy of skull surface landmarks
American Journal of Physical Anthropology, 1988AbstractCraniometric measuremnts from a three‐dimensional (3‐D) digitizing system were compared with those from sliding and spreading calipers. The 3‐D system consisted of a 3‐Space Digitizer, Macintosh Plus computer, and Unigraphics CAD/CAM system. Twenty‐nine standard measurements were made and repeated on two normal and three deformed skulls.
C F, Hildebolt, M W, Vannier
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Accuracy of three-dimensional measurements using cone-beam CT
Dentomaxillofacial Radiology, 2006Lesions causing intraosseous defects in the head and neck region are difficult to diagnose using two-dimensional radiography, and three-dimensional (3D) data provided by CT is useful but often difficult to obtain. Recently, cone-beam CT (CBCT) was made available, with the potential to become a practical tool in dentistry.
H M, Pinsky +4 more
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Increasing the accuracy of imaging-based dimensional measurements
Optics and Photonics for Advanced Dimensional Metrology, 2020More than 95% of industrial inspection systems still rely on pure 2D information. Different measurement tasks like defect detection, micro-structure characterization, spectral characterization and dimensional metrology are typical application scenarios where standard 2D image processing based measurement systems are used.
Tobias Haist +2 more
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The accuracy of measurements of three-dimensional computed tomography reconstructions
Journal of Oral and Maxillofacial Surgery, 1996The purpose of this study was to evaluate the accuracy and reproducibility of linear measurements obtained from three-dimensional reconstructions of computed tomography (CT) scans.Ten rectangular acrylic blocks were prepared with titanium molybdenum alloy (TMA) markers spaced from 1 to 10 mm, respectively.
S W, Covino +3 more
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Measuring Accuracy of Three-Dimensional Displacements in Holographic Interferometry
Applied Optics, 1973In order to establish a quantitative method of measuring the distribution of three-dimensional displacements by holographic interferometry, measuring errors caused by the following two factors are analyzed quantitatively: (i) reading error of fringe order, (ii) setting error of observing and illuminating directions.
T, Matsumoto, K, Iwata, R, Nagata
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Accuracy and reproducibility of 3-dimensional digital model measurements
American Journal of Orthodontics and Dentofacial Orthopedics, 2012The purpose of this study was to evaluate the reliability of measurements made on 3-dimensional digital models obtained with a surface laser scanner (D-250; 3Shape, Copenhagen, Denmark).Twenty orthodontic dental casts of permanent dentitions were selected.
Marinês Vieira S, Sousa +4 more
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High accuracy three-dimensional attitude angle measuring device
Optics and Precision Engineering, 2016A high accuracy measuring device and corresponding measuring method for three;dimensional attitude angles (yaw, pitch and roll) were designed based on an autocollimator and a coordinate rotary transfer matrix. The working principle and structural composition were introduced.
孙国燕 SUN Guo-yan +4 more
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The accuracy of dimensional measurement in ultrasonic real-time scanning
The British Journal of Radiology, 1981The ease of examination with real-time ultrasonic scanners, together with the provision of calipers, combine to make dimensional measurement of anatomical or pathological features an attractive index, that should ideally be independent of the operator.
R C, Chivers, R A, Bacon, T J, Bloomberg
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Dual-frequency fringe for improving measurement accuracy of three-dimensional shape measurement
Chinese Optics Letters, 2021A new phase unwrapping method based on dual-frequency fringe is proposed to improve both high accuracy and large measurement range of three-dimensional shape measurement by synthesizing the projected dual-frequency fringes obtaining higher and lower frequencies.
Zixiao Miao, Qican Zhang
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Accuracy in integrated circuit dimensional measurements
SPIE Proceedings, 1994The measurement of critical dimensions of features on integrated circuits and photomasks is modeled as the comparison of the images of the test object and of a standard object in a measuring device. A length measuring instrument is then a comparator. The calibration of the standard and the conditions necessary for a valid comparison are discussed.
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