Three-dimensional Surface Data Research Articles

Quantitative evaluation of the proximal contact area gap change characterization under intercuspal occlusion by intraoral 3D scanning: Food impaction with tight proximal contact.

This study aimed to present three indicators that represent the proximal contact area gap change under intercuspal occlusion and to see if and how these indicators influence food impaction with tight proximal contact. Ninety volunteers were recruited for bite force measurement and intraoral scanning. Three-dimensional surface data and buccal bite data were obtained for 60 impacted and 60 non-impacted teeth. The scanning data were imported into the Geomagic Studio 2013 to measure three indicators, which included the gap change maximum (Δdm, μm), the buccolingual position of Δdm (P), and the gap expanded buccolingual range (S, mm). The difference between two groups of three indicators and their relationship with food impaction with tight proximal contact were analyzed by the t test, the Pearson chi-squared test, the nonparametric Mann-Whitney U test, and the binary logistic regression analysis (a = 0.05). All indicators (Δdm, P, and S) were statistically different (p < 0.001, p = 0.002, and p < 0.001) in the impacted and non-impacted groups. Food impaction with tight proximal contact was affected by Δdm and S (p < 0.001, p = 0.039), but not by P (p = 0.409). The excessive increase of the gap change maximum and the gap expanded buccolingual range under bite force promoted the occurrence of food impaction with tight proximal contact. The use of intraoral scanning to measure the characteristics of the proximal contact area gap change under bite force may help to deepen our understanding of the pathogenesis of food impaction with tight proximal contact. Importantly it can provide a reference basis for individualizing and quantifying occlusal adjustment treatment.

A Study on Refraction Error Compensation Method for Underwater Spinning Laser Scanning Three-Dimensional Imaging.

Laser scanning 3D imaging technology, because it can obtain accurate three-dimensional surface data, has been widely used in the search for wrecks and rescue operations, underwater resource development, and other fields. At present, the conventional underwater spinning laser scanning imaging system maintains a relatively fixed light window. However, in low-light situations underwater, the rotation of the scanning device causes some degree of water fluctuation, which warps the light strip data that the system sensor receives about the object's surface. To solve this problem, this research studies an underwater 3D scanning and imaging system that makes use of a fixed light window and a spinning laser (FWLS). A refraction error compensation algorithm is investigated that is based on the fundamentals of linear laser scanning imaging, and a dynamic refraction mathematical model is established based on the motion of the imaging device. The results of the experiment on error analysis in an optimal underwater environment indicate that the error in reconstructing the radius is decreased by 60% (from 2.5 mm to around 1 mm) when compensating for the measurement data of a standard sphere with a radius of 20 mm. Moreover, the compensated point cloud data exhibit a higher degree of correspondence with the model of the standard spherical point cloud. Furthermore, we examine the impact of physical noise, measurement distance, and partial occlusion of the object on the imaging system inside an authentic underwater setting. This study is a good starting point for looking at the refractive error of an underwater laser scanning imaging system. It also provides to us some ideas for future research on the refractive error of other scanning imaging methods.

Soft tissue monitoring of the surgical field: detection and tracking of breast surface deformations.

Deformable object tracking is common in the computer vision field, with applications typically focusing on nonrigid shape detection and usually not requiring specific 3D point localization.In surgical guidance however, accurate navigation is intrinsically linked to precise correspondence of tissue structure. This work presents a contactless, automated fiducial acquisition method using stereo video of the operating field to provide reliable fiducial localization for an image guidance framework in breast conserving surgery. On n=8 breasts from healthy volunteers, the breast surface was measured throughout the full range of arm motion in a supine mock-surgical position. Using hand-drawn inked fiducials, adaptive thresholding, and KAZE feature matching, precise three-dimensional fiducial locations were detected and tracked through tool interference, partial and complete marker occlusions, significant displacements and nonrigid shape distortions. Compared to digitization with a conventional optically tracked stylus, fiducials were automatically localized with 1.6 ± 0.5 mm accuracy and the two measurement methods did not significantly differ. The algorithm provided an average false discovery rate <0.1% with all cases' rates below 0.2%. On average, 85.6 ± 5.9% of visible fiducials were automatically detected and tracked, and 99.1 ± 1.1% of frames provided only true positive fiducial measurements, which indicates the algorithm achieves a data stream that can be used for reliable on-line registration. Tracking is robust to occlusions, displacements, and most shape distortions. This work-flow friendly data collection method provides highly accurate and precise three-dimensional surface data to drive an image guidance system for breast conserving surgery.

Measurement Techniques for Three-Dimensional Metrology of High Aspect Ratio Internal Features—A Review

Non-destructive measurements of high aspect ratio microscale features, especially those with internal geometries such as micro-holes, remain a challenging metrology problem that is increasing in difficulty due to the increasing requirement for more complexity and higher tolerances in such structures. Additionally, there is a growing use of functional surface texturing for improving characteristics such as heat transfer and wettability. As a result, measurement techniques capable of providing dimensional form and surface finish for these features are of intense interest. This review explores the state-of-the-art inspection methodologies compatible with high-aspect-ratio structures and their suitability for extracting three-dimensional surface data based on identified high-aspect ratio structure types. Here, the abilities, limitations, challenges, and future requirements for the practical implementation and acceptance of these measurement techniques are presented.

A shape classification scheme for female torso

This paper presents a shape classification scheme for the female torso, based on anthropometric measurements and 3D body scans from a large scale anthropometric survey. The ability to classify the female body shape is highly desired by the clothing industry and apparel researchers for improving pattern design and fit. In order to objectively classify female torso shapes, we employed principal component analysis on torso related anthropometric measurements and three-dimensional (3D) torso surface data to identify the most dominant measurements. The principal component analysis of the anthropometric measurements show that Waist Circumference is the most dominant variable to define overall female torso size, and that Chest-Waist Drop and Waist-Buttock Drop jointly define the local shape of the torso. Using these findings, a torso shape classification scheme was developed, where nine shape categories were defined from Chest-Waist Drop and Waist-Buttock Drop while torso sizes were divided by Waist Circumference. The distribution of nine shape categories is dependent on the value of Waist Circumference. Mean shape of each shape category was then generated from 3D scans.

Data-driven affective product design using complete three-dimensional surface data

As the main part of design display and evaluation, product three-dimensional (3D) form is the core object in affective product design. However, previous research has not yet addressed the development of technical models and method involving complete 3D surface data, and thus cannot guarantee the quality of affective product design. By using the techniques of triangular mesh model, spherical harmonic and conditional variational auto-encoder, this paper proposes a data-driven affective product design method composed of several technical models using complete 3D surface data. These models include: mathematical model for quantifying 3D form, recognition model for recognizing customer’s affective responses, and generative model for generating new 3D forms. For affective product design, the mathematical model achieves the acquisition and processing of complete 3D surface data, the recognition model improves the objectivity and accuracy of recognition by integrating the 3D form data into the calculation process of emotion recognition, and the generative model realizes the automatic generation of new 3D forms in response to emotional data based on the recognition results. Each model provides technical support for realizing the acquisition, processing and generation of complete 3D surface data of product form, and ensures the systematicness and completeness of the proposed method for the affective product design involving 3D form innovation. The feasibility of the method is verified by an example of car design, and the results show that it is an effective affective product design method involving 3D form innovation.

Hydraulic, acid, and proppant-carrying acid fracturing stimulation of volcanic reservoirs in Sichuan Basin, China: an experimental study

Nowadays, volcanic reservoirs show great development potential. However, the stimulation mechanism of volcanic reservoir is yet unclear. In this article, hydraulic fracturing, acid fracturing, and proppant-carrying acid fracturing of volcanic rock were analyzed by the laboratory tests. The average acid etching and proppant-embedded depths were assessed. The effect of different proppant sizes and acid types on fracture conductivity was studied. The results indicate that acid fracturing is failed to produce high-conductivity fractures. Large-sized proppants had larger embedded depths. For the hydraulic fracturing, the average depth of the 30/50 mesh proppant (5 kg/m2, 60 MPa) embedded in the volcanic rock is 33 μm, and the conductivity is 45.27 D·cm, which is 1.5 times that of the 40/70 mesh proppant. Embedded depth of proppant in the proppant-carrying acid fracturing (347 μm) was ten times larger than that in hydraulic fracturing (33 μm), but in terms of conductivity, hydraulic fracturing is only 20% better than proppant-carrying acid fracturing. This study is helpful to elucidate the mechanism of different stimulation methods and provide scientific means for the efficient development of volcanic reservoirs. Highlights In this article, experimental study is made on the stimulation mode of volcanic reservoir. There are few studies on volcanic. This study is helpful to elucidate the mechanism of different stimulation methods and provide scientific means for the efficient development of volcanic reservoirs. Based on the three-dimensional (3D) surface data of the rock, the average acid etching depth and the average embedding depth of proppant are accurately calculated by a new method. The experimental results can provide a good basis for the selection of volcanic reservoir stimulation. The embedded depth and etching depth have an intuitive image display.

New method to evaluate sequelae of static facial asymmetry in patients with facial palsy using three-dimensional scanning analysis

ObjectiveDuring the process of neural recovery after facial palsy, distressing sequelae of static and dynamic facial asymmetry develop in patients with facial palsy. A pronounced nasolabial fold is mainly responsible for static facial asymmetry, which leads to many psychological and social problems in patients. Objective and qualitative assessment of facial appearance is critical to determine the severity of sequelae of static facial asymmetry and whether an intervention is effective for treatment. In the present study, an attempt was made to develop three-dimensional analysis method to assess sequelae of static facial asymmetry after facial palsy. MethodsEight patients with sequelae of facial asymmetry after facial palsy and ten healthy volunteers were enrolled. We used three-dimensional scanning analysis with a portable non-contact optical scanner to obtain three-dimensional surface data from a patient's face and produced a three-dimensional digital model of the face. We then identified a reference plane fixed with the patient's face, and measured the depth of the nasolabial fold of the face. ResultsThe nasolabial fold of the face on the affected side was significantly deeper than that on the unaffected side in patients with sequelae of static facial asymmetry after facial palsy. However, the depth of the facial nasolabial fold on the right side was not different from that on the left side in healthy volunteers. Affected-unaffected side differences in the depth of the nasolabial fold in patients with sequelae of static facial asymmetry after facial palsy were significantly larger than left-right differences in the depth of the nasolabial fold in healthy volunteers. Two weeks after treatment with botulinum toxin injection to the affected zygomaticus muscles, affected-unaffected side differences in the depth of the nasolabial fold were significantly decreased in the patients. In the patients who received botulinum toxin, the absolute values of affected-unaffected side differences in the depth of the nasolabial fold measured using the three-dimensional scanning analysis showed a significant positive correlation with the visual analog scale scores of facial asymmetry marked by independent doctors. ConclusionThe present findings suggest that affected-unaffected side differences in the depth of the nasolabial fold of the measured using three-dimensional scanning analysis can be used as an index of sequelae of static facial asymmetry. It is also suggested that the index can evaluate whether interventions are effective for the treatment of sequelae.

Estimation of beef cow body condition score: a machine learning approach using three-dimensional image data and a simple approach with heart girth measurements

Body condition score (BCS) is a proxy for evaluating body fat reserves. However, monitoring BCS is a time-consuming and subjective task. Thus, we aimed to develop a method for estimating the BCS of beef cows using three-dimensional (3D) body features of cows’ rump area derived from 3D camera data. Three-dimensional surface data of the rump area from 39 multiparous cows were obtained using a 3D camera, and four 3D body features were extracted. The BCSs of the cows were scored by experts, and models for predicting BCS by 3D features were developed using machine learning algorithms. The derived model yielded an overall accuracy, precision, sensitivity, and F-measure of 90%, 88%, 90%, and 88%, respectively. Additionally, we evaluated a simple practical method to estimate BCS using the difference between heart girth (HG) and tightened heart girth (THG) for 118 multiparous cows. A cumulative logistic regression model for estimating BCS by the difference was developed, and the derived generalized coefficient of determination was 0.81. These results suggest that 3D images are useful for estimating the BCS of beef cows and that the difference between HG and THG can be used to estimate BCS as a simple practical method.

Promoting the pavement skid resistance estimation by extracting tire-contacted texture based on 3D surface data

The pavement skid resistance is of vital importance for road safety and maintenance. The existing studies mainly calculates various parameters of pavement texture to evaluate the skid resistance. However, most researchers mainly calculate the whole texture parameters, but rarely consider which part of the texture is actually involved in the friction. This paper studies the measurement and calculation of the tire-pavement contact area and its influence on the skid resistance prediction. In this study, we proposed a set of methods to predict the rubber-contacted pavement area percentage and to extract the rubber-contacted texture. Besides, the skid resistance prediction models based on high-resolution three-dimensional (3D) surface data of the whole and the contacted texture are built and compared. The results show that when the rubber-contacted percentage is set at 20% or ̃% (the predicted percentages), the accuracy of the prediction model is higher. It is demonstrated that the performance of the skid resistance prediction will be improved by extracting the contacted texture. Also, the amount of data can be considerably reduced, which will effectively relieves computational cost.

Effect of curvature correction on parameters extracted from hyperspectral images.

.Significance: Hyperspectral imaging (HSI) has emerged as a promising optical technique. Besides optical properties of a sample, other sample physical properties also affect the recorded images. They are significantly affected by the sample curvature and sample surface to camera distance. A correction method to reduce the artifacts is necessary to reliably extract sample properties.Aim: Our aim is to correct hyperspectral images using the three-dimensional (3D) surface data and assess how the correction affects the extracted sample properties.Approach: We propose the combination of HSI and 3D profilometry to correct the images using the Lambert cosine law. The feasibility of the correction method is presented first on hemispherical tissue phantoms and next on human hands before, during, and after the vascular occlusion test (VOT).Results: Seven different phantoms with known optical properties were created and imaged with a hyperspectral system. The correction method worked up to 60 deg inclination angle, whereas for uncorrected images the maximum angles were 20 deg. Imaging hands before, during, and after VOT shows good agreement between the expected and extracted skin physiological parameters.Conclusions: The correction method was successfully applied on the images of tissue phantoms of known optical properties and geometry and VOT. The proposed method could be applied to any reflectance optical imaging technique and should be used whenever the sample parameters need to be extracted from a curved surface sample.

Surface Defect Detection on Nuclear Power Plant Components Based on Photometric Stereo under Near-Field LED Light

To improve the visual inspection of nuclear power plant components, this study introduces the technology of three-dimensional reconstruction framework based on photo metric stereo under near-field LED lighting. An iterative algorithm is proposed to estimate the K value of different light sources and the light6 intensities for various image pixels. Combined with the calculation method of the spatial position of the light source and the detected surface points, the light intensity and light direction of different points on the detected surface are estimated under the illumination of near-field LED point light source. A surface defect detection system is designed based on this technology, and it is verified by experiments on surface damage samples and actual nuclear power equipment. The results show that this system can obtain three-dimensional surface data, and for scratch-type defects, it can further achieve accurate depth measurement. Therefore, it can effectively improve the detection ability of surface defects.

Three-Dimensional Photogrammetric Facial Soft Tissue Analysis of Egyptian Female Adolescents with Accepted Normal Occlusion (Cross sectional study)

Background: Soft tissue normal values represent useful guidelines for proper diagnosis and evaluation of orthodontic patients. The objective of this cross-sectional study is to determine the normal values of the vertical facial soft tissue of Egyptian female adolescents. Methodology: Thirty female Participants 11-15 years of age with balanced facial proportions, full permanent dentition and Angle Class I molar and canine relationship were included in this study. Three-dimensional surface data was acquired using Planmeca ProMax 3D ProFace unit. The participant’s data was admitted to the Planmeca Romexis 4.5.0.R software in the associated computer unit prior to the imaging procedure. For all processed images five standard anthropometric landmarks were identified to perform our measurements: Trichion (Tr`), Gnathion (Gn`), Nasion(N`), Subnasale (Sn`) and Sublabiale (Sl`). Results: The mean anterior face height (Tr-Gn’) for the total sample was found 172.6mm±7.99mm. While, the mean height of the forehead (Tr-N’) for total sample was 63.6mm ±7.5mm. The mean morphological height of the face (N’-Gn) was 112.6mm +6.4mm The mean lower face height (Sn-Gn’) was 64.2mm ±5.3mm. The chin height (Sl-Gn’) for the total sample was 22.9mm±2.6mm. Conclusion: Soft tissue normal values represent useful guidelines for proper diagnosis and evaluation of orthodontic patients. Most of the facial measurements of Egyptian female adolescents were can be different or similar according to different ethnic groups.

Feasibility of 3-Dimensional Visual Guides for Preparing Pediatric Zirconia Crowns: An In Vitro Study.

This study evaluated the feasibility of a tooth preparation guide for prefabricated zirconia crowns (PZCs). Three-dimensional surface data for PZCs of the left maxillary primary first molar and left mandibular primary second molar were obtained using a model scanner. The tooth preparation data were digitally designed to harmonize with the adjacent teeth on the mixed dentition model and visualized using a color-coded map, which presents the required amount of tooth reduction. Twenty participants were recruited for preparing teeth with and without using the tooth preparation guide. The following three parameters were evaluated: tooth preparation time, harmony score, and amount of tooth reduction. The preparation time when using the guide was significantly reduced (p < 0.05), and a significant difference was observed in the harmony scores for the maxillary primary first molar preparation. Furthermore, the amount of tooth reduction was significantly different for both maxillary and mandibular primary molars (p < 0.05) in terms of the occlusal distal surface and buccal line angle in the maxillary primary first molars, and the smooth surfaces, proximal surfaces, and mesial line angles in the mandibular primary second molars. Thus, the results suggest that a tooth preparation guide could facilitate better tooth preparation for PZCs.

Spatial and temporal variations in glacier aerodynamic surface roughness during the melting season, as estimated at the August-one ice cap, Qilian mountains, China

Abstract. The aerodynamic roughness of glacier surfaces is an important factor governing turbulent heat transfer. Previous studies rarely estimated spatial and temporal variation in aerodynamic surface roughness (z0) over a whole glacier and whole melting season. Such observations can do much to help us understand variation in z0 and thus variations in turbulent heat transfer. This study, at the August-one ice cap in the Qilian mountains, collected three-dimensional ice surface data at plot scale, using both automatic and manual close-range digital photogrammetry. Data were collected from sampling sites spanning the whole ice cap for the whole of the melting season. The automatic site collected daily photogrammetric measurements from July to September of 2018 for a plot near the center of the ice cap. During this time, snow cover gave way to ice and then returned to snow. z0 was estimated based on micro-topographic methods from automatic and manual photogrammetric data. Manual measurements were taken at sites from the terminals to the top of the ice cap; they showed that z0 was larger at the snow and ice transition zone than in areas that are fully snow or ice covered. This zone moved up the ice cap during the melting season. It is clear that persistent snowfall and rainfall both reduce z0. Using data from a meteorological station near the automatic photogrammetry site, we were able to calculate surface energy balances over the course of the melting season. We found that high or rising turbulent heat, as a component of surface energy balance, tended to produce a smooth ice surface and a smaller z0 and that low or decreasing turbulent heat tended to produce a rougher surface and larger z0.

How smooth is a dolphin? The ridged skin of odontocetes.

Dolphin skin has long been an inspiration for research on drag reduction mechanisms due to the presence of skin ridges that could reduce fluid resistance. We gathered in vivo three-dimensional surface data on the skin from five species of odontocetes to quantitatively examine skin texture, including the presence and size of ridges. We used these data to calculate k+ values, which relate surface geometry to changes in boundary layer flow. Our results showed that while ridge size differs among species, odontocete skin was surprisingly smooth compared to the skin of other swimmers (average roughness = 5.3 µm). In addition, the presence of ridges was variable among individuals of the same species. We predict that odontocete skin ridges do not alter boundary layer flows at cruising swimming speeds. By combining k+ values and morphological data, our work provides evidence that skin ridges are unlikely to be an adaptation for drag reduction and that odontocete skin is exceptionally smooth compared to other pelagic swimmers.

A path planning method for a surface inspection system based on two-dimensional laser profile scanner

In this article, a method for two-dimensional scanning path planning based on robot is proposed. In this method, a section division algorithm based on neighborhood search method for scanning orientation determination is firstly produced. The scanning paths which meet constraints of the system are then generated. Finally, the experiment is carried out on robot-based scanning platform. The two-dimensional data from scanner and the robot position are combined to form three-dimensional surface data of measured workpiece. The experiment results verify the effectiveness of proposed method.

Robust subaperture stitching method based on three-dimensional surface data matching

In the interferometric subaperture stitching, the subaperture-overlapped regions are often inaccurately positioned due to positioning error. To achieve better stitching effect, we propose a robust subaperture stitching method based on three-dimensional surface data matching. Speeded up robust features algorithm is used to calculate the relative displacements of adjacent subapertures, and subsequent pose adjusting is performed according to the displacements. The method needs neither auxiliary measures nor a known initial displacement value, which can eliminate the dependence on the precision of the mechanical device of the subaperture stitching. Experiments show that the proposed method can obtain smooth, mosaic-free surface results without dislocation.

Gender differences in knee morphology and the prospects for implant design in total knee replacement

BackgroundMorphological differences between female and male knees have been reported in the literature, which led to the development of so-called gender-specific implants. However, detailed morphological descriptions covering the entire joint are rare and little is known regarding whether gender differences are real sexual dimorphisms or can be explained by overall differences in size. MethodsWe comprehensively analysed knee morphology using 33 features of the femur and 21 features of the tibia to quantify knee shape. The landmark recognition and feature extraction based on three-dimensional surface data were fully automatically applied to 412 pathological (248 female and 164 male) knees undergoing total knee arthroplasty. Subsequently, an exploratory statistical analysis was performed and linear correlation analysis was used to investigate normalization factors and gender-specific differences. ResultsStatistically significant differences between genders were observed. These were pronounced for distance measurements and negligible for angular (relative) measurements. Female knees were significantly narrower at the same depth compared to male knees. The correlation analysis showed that linear correlations were higher for distance measurements defined in the same direction. After normalizing the distance features according to overall dimensions in the direction of their definition, gender-specific differences disappeared or were smaller than the related confidence intervals. ConclusionsImplants should not be linearly scaled according to one dimension. Instead, features in medial/lateral and anterior/posterior directions should be normalized separately (non-isotropic scaling). However, large inter-individual variations of the features remain after normalization, suggesting that patient-specific design solutions are required for an improved implant design, regardless of gender.

EVALUATING MOBILE LASER SCANNING FOR LANDSLIDE MONITORING

Abstract. Landslide is one of the natural disasters that give a huge impact to human life and social-economic development. Landslide needs to be monitored periodically in order to avoid loss of human life and damages of properties. Various methods have been used for monitoring landslide. This aim of the research is to evaluate the potential of mobile laser scanning technique for monitoring of landslide area. The objectives of the research are to acquire three-dimensional surface data of landslide area in different epochs and to analyze the movement of the landslide area using three-dimensional surface deviation and ground surveying techniques. The methodology begins with the GPS survey for the establishment of ground control points for the project area. The total station survey was then carried out to measure the three-dimensional coordinates of twenty well distributed targets located at the project area. The data collection phase was then continuing with the mobile laser scanning survey. The processing of the two epochs data acquired from both techniques was then carried out simultaneously and the methodology concluded with the output comparison analysis for the movement detection of the land slip. The finding shows that the mobile laser scanning provides fast and accurate data acquisition technique of the landslide surface. The surface deviation analysis of the two epochs laser scanning data was capable to detect the movement occurred in the project area. The results were successfully evaluated using the changes of the three-dimensional coordinates of the targets from the two epoch’s ground surveying data.