Evaluation of the Accuracy of Four Digital Methods by Linear and Volumetric Analysis of Dental Impressions

The quality of dental arch impression has a substantial role in the precision of the intervention. It is traditionally acquired with resins that solidify when in contact with the air. Compared to that method, digital impression gives great advantages and, together with three-dimensional (3D) digitization devices, allows a simplification of the digital impression process. The growing adoption of such systems by a large number of dental clinics determines the need for an in-depth evaluation of the accuracy and the precision of the different systems. The aim of this work is to define a methodology for the evaluation of the accuracy and precision of 3D intraoral and desktop scanning systems, by using volumetric and linear methods. The replica of a tooth was realized with zirconium; afterward, high-accuracy point clouds of the master model were acquired by a coordinate measurement machine (CMM). In this way, the dimensions of the replica were accurately known. An intraoral scanner (I) and three desktops (D1, D2, D3) were then used to scan the replica. The geometry resulting from the CMM was compared with the ones derived from the scanners, using two different commercial programs (Geomagic and 3-Matic) and a custom-developed algorithm (MATLAB). Geomagic showed the mean values to be in a range from 0.0286 mm (D1) to 0.1654 mm (I), while 3-Matic showed mean values from −0.0396 mm (D1) to 0.1303 mm (I). MATLAB results ranged from 0.00014 mm (D1) to 0.00049 mm (D2). The probability distributions of the volumetric error of the measurements obtained with the different scanners allow a direct comparison of their performances. For the results given by our study, the volumetric approach that we adopted appears to be an excellent system of analysis.

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A New Method to Evaluate Trueness and Precision of Digital and Conventional Impression Techniques for Complete Dental Arch

Applied Sciences ◽

10.3390/app11104612 ◽

2021 ◽

Vol 11 (10) ◽

pp. 4612

Author(s):

KweonSoo Seo ◽

Sunjai Kim

Keyword(s):

Intraclass Correlation ◽

Three Dimensional ◽

New Method ◽

Digital Impression ◽

Dental Arch ◽

Digital Models ◽

Digital Impressions ◽

Measuring Machine ◽

Master Model ◽

Conventional Impression

Purpose: The aim of this study was to present a new method to analyze the three-dimensional accuracy of complete-arch dental impressions and verify the reliability of the method. Additionally, the accuracies of conventional and intraoral digital impressions were compared using the new method. Methods: A master model was fabricated using 14 milled polyetheretherketone cylinders and a maxillary acrylic model. Each cylinder was positioned and named according to its corresponding tooth position. Twenty-five definitive stone casts were fabricated using conventional impressions of the master model. An intraoral scanner was used to scan the master model 25 times to fabricate 25 digital models. A coordinate measuring machine was used to physically probe each cylinder in the master model and definitive casts. An inspection software was used to probe cylinders of digital models. A three-dimensional part coordinate system was defined and used to compute the centroid coordinate of each cylinder. Intraclass correlation coefficient (ICC) was evaluated to examine the reliability of the new method. Independent two sample t-test was performed to compare the trueness and precision of conventional and intraoral digital impressions (α = 0.05). Results: ICC results showed that, the new method had almost perfect reliability for the measurements of the master model, conventional and digital impression. Conventional impression showed more accurate absolute trueness and precision than intraoral digital impression for most of the tooth positions (p < 0.05). Conclusions: The new method was reliable to analyze the three-dimensional deviation of complete-arch impressions. Conventional impression was still more accurate than digital intraoral impression for complete arches.

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ASSESSING THE ACCURACY AND PRECISION OF IMPERFECT POINT CLOUDS FOR 3D INDOOR MAPPING AND MODELING

ISPRS Annals of Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-annals-iv-4-w6-3-2018 ◽

2018 ◽

Vol IV-4/W6 ◽

pp. 3-10

Author(s):

J. Chen ◽

O. E. Mora ◽

K. C. Clarke

Keyword(s):

Low Cost ◽

Random Noise ◽

Three Dimensional ◽

Laser Scanner ◽

Point Clouds ◽

Accuracy And Precision ◽

Wide Range ◽

Sharp Edges ◽

The Cost ◽

Indoor Spaces

<p><strong>Abstract.</strong> In recent years, growing public interest in three-dimensional technology has led to the emergence of affordable platforms that can capture 3D scenes for use in a wide range of consumer applications. These platforms are often widely available, inexpensive, and can potentially find dual use in taking measurements of indoor spaces for creating indoor maps. Their affordability, however, usually comes at the cost of reduced accuracy and precision, which becomes more apparent when these instruments are pushed to their limits to scan an entire room. The point cloud measurements they produce often exhibit systematic drift and random noise that can make performing comparisons with accurate data difficult, akin to trying to compare a fuzzy trapezoid to a perfect square with sharp edges. This paper outlines a process for assessing the accuracy and precision of these imperfect point clouds in the context of indoor mapping by integrating techniques such as the extended Gaussian image, iterative closest point registration, and histogram thresholding. A case study is provided at the end to demonstrate use of this process for evaluating the performance of the Scanse Sweep 3D, an ultra-low cost panoramic laser scanner.</p>

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Accuracy and precision of polyurethane dental arch models fabricated using a three-dimensional subtractive rapid prototyping method with an intraoral scanning technique

The Korean Journal of Orthodontics ◽

10.4041/kjod.2014.44.2.69 ◽

2014 ◽

Vol 44 (2) ◽

pp. 69 ◽

Cited By ~ 25

Author(s):

Jae-Hong Kim ◽

Ki-Baek Kim ◽

Woong-Chul Kim ◽

Ji-Hwan Kim ◽

Hae-Young Kim

Keyword(s):

Rapid Prototyping ◽

Three Dimensional ◽

Dental Arch ◽

Arch Models ◽

Intraoral Scanning ◽

Scanning Technique ◽

Accuracy And Precision

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EVALUATION OF HISTORICAL HERITAGE DOCUMENTATION: REALITY BASED SURVEY AND DERIVATIVE MODELS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-w17-115-2019 ◽

2019 ◽

Vol XLII-2/W17 ◽

pp. 115-122

Author(s):

A. di Luggo ◽

M. Campi ◽

L. Repola ◽

V. Cera ◽

S. Scandurra ◽

...

Keyword(s):

Three Dimensional ◽

Point Clouds ◽

Artistic Value ◽

North East ◽

The North ◽

Accuracy And Precision ◽

First Results ◽

The Subject ◽

Historical Heritage

Abstract. Three-dimensional acquisition systems for architecture have significantly evolved over just a few decades, with them allowing point clouds to be generated through active and passive optical sensor equipment.Accuracy levels vary considerably in relation to both the equipment and techniques used, with the data obtained acting as a scaffolding for the creation of derived models that allow specific analyses to be carried out.Ongoing research on Palazzo Donn’Anna, a Neapolitan sixteenth-century building of particular historical and artistic value, is being carried out in this context and the first results are presented in this paper.The entire building has been the subject of an instrumental survey. The north-east façade was proposed as a case-study for the experimentation of diversified reality-based sensors so as to compare the accuracy and precision of the data. The comparison was also aimed at evaluating the performance of some processing softwares. Finally, in order to obtain an estimate of the data in the transcription from the point cloud to a derived 3D model, the reproduction of the same portion of the prospectus in a derivative model of both object-oriented and NURBS types was experimented.

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An Accelerated Cue Combination Principle Accounts for Multi-cue Depth Perception

Journal of Perceptual Imaging ◽

10.2352/j.percept.imaging.2020.3.1.010501 ◽

2020 ◽

Vol 3 (1) ◽

pp. 10501-1-10501-9

Author(s):

Christopher W. Tyler

Keyword(s):

Belief Propagation ◽

Probability Distributions ◽

Three Dimensional ◽

Dimensional Structure ◽

Fusion Model ◽

Cue Combination ◽

Depth Estimate ◽

Appropriate Behavior ◽

Depth Cues ◽

Bayesian Averaging

Abstract For the visual world in which we operate, the core issue is to conceptualize how its three-dimensional structure is encoded through the neural computation of multiple depth cues and their integration to a unitary depth structure. One approach to this issue is the full Bayesian model of scene understanding, but this is shown to require selection from the implausibly large number of possible scenes. An alternative approach is to propagate the implied depth structure solution for the scene through the “belief propagation” algorithm on general probability distributions. However, a more efficient model of local slant propagation is developed as an alternative.The overall depth percept must be derived from the combination of all available depth cues, but a simple linear summation rule across, say, a dozen different depth cues, would massively overestimate the perceived depth in the scene in cases where each cue alone provides a close-to-veridical depth estimate. On the other hand, a Bayesian averaging or “modified weak fusion” model for depth cue combination does not provide for the observed enhancement of perceived depth from weak depth cues. Thus, the current models do not account for the empirical properties of perceived depth from multiple depth cues.The present analysis shows that these problems can be addressed by an asymptotic, or hyperbolic Minkowski, approach to cue combination. With appropriate parameters, this first-order rule gives strong summation for a few depth cues, but the effect of an increasing number of cues beyond that remains too weak to account for the available degree of perceived depth magnitude. Finally, an accelerated asymptotic rule is proposed to match the empirical strength of perceived depth as measured, with appropriate behavior for any number of depth cues.

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A mobile stereo vision system with variable baseline distance for three-dimensional coordinate measurement in large FOV

Measurement ◽

10.1016/j.measurement.2021.109086 ◽

2021 ◽

Vol 175 ◽

pp. 109086

Author(s):

Yue Wang ◽

Xiangjun Wang

Keyword(s):

Stereo Vision ◽

Vision System ◽

Three Dimensional ◽

Coordinate Measurement ◽

Stereo Vision System ◽

Three Dimensional Coordinate

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Multi-Dimensional Underwater Point Cloud Detection Based on Deep Learning

Sensors ◽

10.3390/s21030884 ◽

2021 ◽

Vol 21 (3) ◽

pp. 884

Author(s):

Chia-Ming Tsai ◽

Yi-Horng Lai ◽

Yung-Da Sun ◽

Yu-Jen Chung ◽

Jau-Woei Perng

Keyword(s):

Deep Learning ◽

Point Cloud ◽

Three Dimensional ◽

Point Clouds ◽

Training Data ◽

Network Architectures ◽

Point Cloud Data ◽

Data Types ◽

Raw Data ◽

Cloud Data

Numerous sensors can obtain images or point cloud data on land, however, the rapid attenuation of electromagnetic signals and the lack of light in water have been observed to restrict sensing functions. This study expands the utilization of two- and three-dimensional detection technologies in underwater applications to detect abandoned tires. A three-dimensional acoustic sensor, the BV5000, is used in this study to collect underwater point cloud data. Some pre-processing steps are proposed to remove noise and the seabed from raw data. Point clouds are then processed to obtain two data types: a 2D image and a 3D point cloud. Deep learning methods with different dimensions are used to train the models. In the two-dimensional method, the point cloud is transferred into a bird’s eye view image. The Faster R-CNN and YOLOv3 network architectures are used to detect tires. Meanwhile, in the three-dimensional method, the point cloud associated with a tire is cut out from the raw data and is used as training data. The PointNet and PointConv network architectures are then used for tire classification. The results show that both approaches provide good accuracy.

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Robotic motion compensation for bone movement, using ultrasound images

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-12-2014-0435 ◽

2015 ◽

Vol 42 (5) ◽

pp. 466-474 ◽

Cited By ~ 4

Author(s):

P.M.B. Torres ◽

P. J. S. Gonçalves ◽

J.M.M. Martins

Keyword(s):

Motion Compensation ◽

Optical Measurement ◽

Three Dimensional ◽

Point Clouds ◽

Robotic System ◽

Ultrasound Images ◽

Bone Drilling ◽

Content Type ◽

3D Point Clouds ◽

Robotic Motion

Purpose – The purpose of this paper is to present a robotic motion compensation system, using ultrasound images, to assist orthopedic surgery. The robotic system can compensate for femur movements during bone drilling procedures. Although it may have other applications, the system was thought to be used in hip resurfacing (HR) prosthesis surgery to implant the initial guide tool. The system requires no fiducial markers implanted in the patient, by using only non-invasive ultrasound images. Design/methodology/approach – The femur location in the operating room is obtained by processing ultrasound (USA) and computer tomography (CT) images, obtained, respectively, in the intra-operative and pre-operative scenarios. During surgery, the bone position and orientation is obtained by registration of USA and CT three-dimensional (3D) point clouds, using an optical measurement system and also passive markers attached to the USA probe and to the drill. The system description, image processing, calibration procedures and results with simulated and real experiments are presented and described to illustrate the system in operation. Findings – The robotic system can compensate for femur movements, during bone drilling procedures. In most experiments, the update was always validated, with errors of 2 mm/4°. Originality/value – The navigation system is based entirely on the information extracted from images obtained from CT pre-operatively and USA intra-operatively. Contrary to current surgical systems, it does not use any type of implant in the bone to track the femur movements.

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Comparison of Depth Camera and Terrestrial Laser Scanner in Monitoring Structural Deflections

Sensors ◽

10.3390/s21010201 ◽

2020 ◽

Vol 21 (1) ◽

pp. 201

Author(s):

Michael Bekele Maru ◽

Donghwan Lee ◽

Kassahun Demissie Tola ◽

Seunghee Park

Keyword(s):

Optical Sensors ◽

Point Cloud ◽

Three Dimensional ◽

Laser Scanner ◽

Point Clouds ◽

Depth Camera ◽

Terrestrial Laser Scanner ◽

Cloud Data ◽

3D Point Clouds ◽

3D Information

Modeling a structure in the virtual world using three-dimensional (3D) information enhances our understanding, while also aiding in the visualization, of how a structure reacts to any disturbance. Generally, 3D point clouds are used for determining structural behavioral changes. Light detection and ranging (LiDAR) is one of the crucial ways by which a 3D point cloud dataset can be generated. Additionally, 3D cameras are commonly used to develop a point cloud containing many points on the external surface of an object around it. The main objective of this study was to compare the performance of optical sensors, namely a depth camera (DC) and terrestrial laser scanner (TLS) in estimating structural deflection. We also utilized bilateral filtering techniques, which are commonly used in image processing, on the point cloud data for enhancing their accuracy and increasing the application prospects of these sensors in structure health monitoring. The results from these sensors were validated by comparing them with the outputs from a linear variable differential transformer sensor, which was mounted on the beam during an indoor experiment. The results showed that the datasets obtained from both the sensors were acceptable for nominal deflections of 3 mm and above because the error range was less than ±10%. However, the result obtained from the TLS were better than those obtained from the DC.

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