Three-dimensional Data Acquisition Research Articles

A Multiscale Study on the Morphology and Evolution of Slip Bands in a Nickel-Based Superalloy During Low Cycle Fatigue

Plastic deformation during low cycle fatigue in fcc materials with low stacking fault energy is accumulated in slip bands, which become preferential sites for crack initiation. Whilst these dislocation structures have been studied before, little has been done to assess the effect and evolution of the individual slip lines within them. In this study, samples of a γ′ precipitate strengthened nickel-based superalloy are fatigued at room temperature and 700˚C for 1, 40 and 500 cycles. The resulting dislocation structures are characterised via Electron Channeling Contrast Imaging and Transmission Electron Microscopy. We introduce a new methodology to measure slip band parameters such as the slip line spacing and shear step length by analysing the holes left by sheared precipitates in γ′-etched secondary electron micrographs. Statistics of these parameters are obtained and compared for different conditions. Advantages of this technique include resolution at the scale of individual planes, acquisition of true three-dimensional data and applicability in the bulk of the material. The combination of these techniques provides a unique mechanistic and quantitative insight into the slip band and precipitate morphology evolution.

Recent Advances in 3D Data Acquisition and Processing by Time-of-Flight Camera

Three-dimensional (3D) data acquisition and real-time processing is a critical issue in an artificial vision system. The developing time-of-flight (TOF) camera as a real-time vision sensor for obtaining depth images has now received wide attention, due to its great potential in many areas, such as 3D perception, computer vision, robot navigation, human–machine interaction, augmented reality, and so on. This paper survey advances in TOF imaging technology mainly from the last decade. We focus only on recent progress of overcoming limitations such as systematic errors, object boundary ambiguity, multipath error, phase wrapping, and motion blur, and address the theoretical principles and future research trends as well.

Maize Plant Phenotyping: Comparing 3D Laser Scanning, Multi-View Stereo Reconstruction, and 3D Digitizing Estimates

High-throughput phenotyping technologies have become an increasingly important topic of crop science in recent years. Various sensors and data acquisition approaches have been applied to acquire the phenotyping traits. It is quite confusing for crop phenotyping researchers to determine an appropriate way for their application. In this study, three representative three-dimensional (3D) data acquisition approaches, including 3D laser scanning, multi-view stereo (MVS) reconstruction, and 3D digitizing, were evaluated for maize plant phenotyping in multi growth stages. Phenotyping traits accuracy, post-processing difficulty, device cost, data acquisition efficiency, and automation were considered during the evaluation process. 3D scanning provided satisfactory point clouds for medium and high maize plants with acceptable efficiency, while the results were not satisfactory for small maize plants. The equipment used in 3D scanning is expensive, but is highly automatic. MVS reconstruction provided satisfactory point clouds for small and medium plants, and point deviations were observed in upper parts of higher plants. MVS data acquisition, using low-cost cameras, exhibited the highest efficiency among the three evaluated approaches. The one-by-one pipeline data acquisition pattern allows the use of MVS high-throughput in further phenotyping platforms. Undoubtedly, enhancement of point cloud processing technologies is required to improve the extracted phenotyping traits accuracy for both 3D scanning and MVS reconstruction. Finally, 3D digitizing was time-consuming and labor intensive. However, it does not depend on any post-processing algorithms to extract phenotyping parameters and reliable phenotyping traits could be derived. The promising accuracy of 3D digitizing is a better verification choice for other 3D phenotyping approaches. Our study provides clear reference about phenotyping data acquisition of maize plants, especially for the affordable and portable field phenotyping platforms to be developed.

3DmFV: Three-Dimensional Point Cloud Classification in Real-Time Using Convolutional Neural Networks

Modern robotic systems are often equipped with a direct three-dimensional (3-D) data acquisition device, e.g., LiDAR, which provides a rich 3-D point cloud representation of the surroundings. This representation is commonly used for obstacle avoidance and mapping. Here, we propose a new approach for using point clouds for another critical robotic capability, semantic understanding of the environment (i.e., object classification). Convolutional neural networks (CNNs), that perform extremely well for object classification in 2-D images, are not easily extendible to 3-D point clouds analysis. It is not straightforward due to point clouds' irregular format and a varying number of points. The common solution of transforming the point cloud data into a 3-D voxel grid needs to address severe accuracy versus memory size tradeoffs. In this letter, we propose a novel, intuitively interpretable, 3-D point cloud representation called 3-D modified Fisher vectors. Our representation is hybrid as it combines a coarse discrete grid structure with continuous generalized Fisher vectors. Using the grid enables us to design a new CNN architecture for real-time point cloud classification. In a series of performance analysis experiments, we demonstrate competitive results or even better than state of the art on challenging benchmark datasets while maintaining robustness to various data corruptions.

Preliminary feasibility study on differential diagnosis between radiation-induced cerebral necrosis and recurrent brain tumor by means of [18F]fluoro-borono-phenylalanine PET/CT.

A previous study reported that a differential diagnosis between glioblastoma progression and radiation necrosis by 4-borono-2-[18F]-fluoro-phenylalanine ([18F]FBPA) PET can be made based on lesion-to-normal ratio of [18F]FBPA accumulation. Two-dimensional data acquisition mode PET alone system, with in-plane resolution of 7.9mm and axial resolution of 13.9mm, was used. In the current study, we aimed to confirm the differential diagnostic capability of [18F]FBPA PET/CT with higher PET spatial resolution by three-dimensional visual inspection and by measuring mean standardized uptake value (SUVmean), maximum SUV (SUVmax), metabolic tumor volume (MTV), and total lesion (TL) [18F]FBPA uptake. Twelve patients of glioma (9), malignant meningioma (1), hemangiopericytoma (1), and metastatic brain tumor (1) were enrolled. All had preceding radiotherapy. High-resolution three-dimensional data acquisition mode PET/CT with in-plane resolution of 4.07mm and axial resolution of 5.41mm was employed for imaging. Images were three-dimensionally analyzed using the PMOD software. SUVmean and SUVmax of lesion and normal brain were measured. Lesion MTV and TL FBPA uptake were calculated. The diagnostic accuracy of [18F]FBPA PET/CT in detecting recurrence (n = 6) or necrosis (n = 6) was verified by clinical follow-up. All parameters showed significantly higher values for tumor recurrence than for necrosis. SUVmean in recurrence was 2.95 ± 0.84 vs 1.18 ± 0.24 in necrosis (P = 0.014); SUVmax in recurrence was 4.63 ± 1.23 vs 1.93 ± 0.44 in necrosis (P = 0.014); MTV in recurrence was 44.92 ± 28.93mL vs 10.66 ± 8.46mL in necrosis (P = 0.032); and mean TL FBPA uptake in recurrence was 121.01 ± 50.48g vs 12.36 ± 9.70g in necrosis (P = 0.0029). In this preliminary feasibility study, we confirmed the possibility of differentiating tumor recurrence from radiation necrosis in patients with irradiated brain tumors by [18F]FBPA PET/CT using indices of SUVmean, SUVmax, MTV, and TL 18FBPA uptake.

A System for the Acquisition and Analysis of Three-Dimensional Data Describing Dental Morphology

Accurate, reproducible three-dimensional (3D) data provide an important contribution to our ability to describe, compare and understand dental morphology but the existing technology is often expensive or has technical limitations. Recently available, inexpensive 3D profilometers interfaced with standard personal computers offer the potential to overcome some of these problems. This technical note describes a system that uses a 3D profilometer and purpose written software to analyse changes in dental morphology resulting from tooth wear. The validity of the derived data was determined by comparing data derived from scans of objects of known dimensions with calculated volumes. These differences were less than 10% from objects that were difficult to scan because of their geometry and were commonly less than 5%. The reproductibility, expressed as intra- and inter-observer coefficients of variation, was less than 1%. The potential applications of systems of this type are outlined.

Extraction and Classification of Human Body Parameters for Gait Analysis

Human gait analysis is considered a new biometric tool for the ability to obtain metrics from the body at a distance. Biometric identifiers have properties that can technologically measure and analyze the characteristics of the human body and can be used as a form of identification and access control for security applications. Recognition through proper interpretation of gait parameters has become a relevant pattern classification problem. This work aims to develop an image processing system, with the use of the Microsoft Kinect sensor, which is capable to extract movement patterns for gait analysis and to present a comparative study of different pattern recognition methods for human identification. The image processing system, developed in C#, allowed the acquisition of three-dimensional data from several volunteers and made it possible to identify the human skeleton and automatically extract the kinetic and kinematic parameters of the body. For data analysis, different classification methods were compared. Among them, the algorithms that presented better performance were probabilistic neural networks, deep neural networks and k-nearest neighbors, with nearly 99% correct recognition rate. The obtained results demonstrate the efficiency of gait analysis as a biometric method. They also show the viability of gait parameter extraction using the Kinect sensor and the good performance of pattern recognition methods applied to the acquired gait kinetic and kinematic parameters.

Disrupted functional connectivity within the default mode network and salience network in unmedicated bipolar II disorder

BackgroundRecent studies demonstrate that functional disruption in resting-state networks contributes to cognitive and affective symptoms of bipolar disorder (BD), however, the functional connectivity (FC) pattern underlying BD II depression within the default mode network (DMN), salience network (SN), and frontoparietal network (FPN) is still not well understood. The primary aim of this study was to explore whether the pathophysiology of BD II derived from the pattern of FC within the DMN, SN, and FPN by using seed-based FC approach of resting-state functional magnetic resonance imaging (rs-fMRI). MethodsNinety-six BD II patients and 100 HCs underwent rs-fMRI and three-dimensional structural data acquisition. All patients were either drug naive or unmedicated for at least 6 months. The following four regions of interest were used to conduct seed-based FC: the left posterior cingulate cortex (PCC) seed to probe the DMN, the left subgenual anterior cingulate cortex (sgACC) and amygdala seeds to probe the SN, the left dorsal lateral prefrontal cortex (dlPFC) seed to probe the FPN. ResultsCompared with HCs, patients with BD II demonstrated hypoconnectivity of the left PCC to the bilateral medial prefrontal cortex (mPFC) and bilateral precuneus/PCC, and of the left sgACC to the right inferior temporal gyrus (ITG); nevertheless, the left amygdala and dlPFC had no within-network hypo- or hyperconnectivity to any other SN and FPN regions. ConclusionOur findings suggest that disrupted FC is located in the DMN and SN, especially in the PCC-mPFC and precuneus/PCC, and sgACC-ITG connectivity in BD II patients.

Abstracts of the Total Body PET conference 2018

Abstracts of the Total Body PET conference 2018

Single breath-hold 3D cardiac T1 mapping using through-time spiral GRAPPA.

The quantification of cardiac T1 relaxation time holds great potential for the detection of various cardiac diseases. However, as a result of both cardiac and respiratory motion, only one two-dimensional T1 map can be acquired in one breath-hold with most current techniques, which limits its application for whole heart evaluation in routine clinical practice. In this study, an electrocardiogram (ECG)-triggered three-dimensional Look-Locker method was developed for cardiac T1 measurement. Fast three-dimensional data acquisition was achieved with a spoiled gradient-echo sequence in combination with a stack-of-spirals trajectory and through-time non-Cartesian generalized autocalibrating partially parallel acquisition (GRAPPA) acceleration. The effects of different magnetic resonance parameters on T1 quantification with the proposed technique were first examined by simulating data acquisition and T1 map reconstruction using Bloch equation simulations. Accuracy was evaluated in studies with both phantoms and healthy subjects. These results showed that there was close agreement between the proposed technique and the reference method for a large range of T1 values in phantom experiments. In vivo studies further demonstrated that rapid cardiac T1 mapping for 12 three-dimensional partitions (spatial resolution, 2×2×8mm3 ) could be achieved in a single breath-hold of ~12s. The mean T1 values of myocardial tissue and blood obtained from normal volunteers at 3T were 1311±66 and 1890±159ms, respectively. In conclusion, a three-dimensional T1 mapping technique was developed using a non-Cartesian parallel imaging method, which enables fast and accurate T1 mapping of cardiac tissues in a single short breath-hold.

Computation of road geometry parameters using mobile LiDAR system

The continuous assessment of road geometry parameters is important for road condition analysis and the required maintenance work. Mobile LiDAR system (MLS) is being frequently used for roadway data collection due to its capability of accurate and dense three-dimensional data acquisition at highway speed. The high-precision road terrain obtained in terms of the point cloud is used as primary data for road geometry parameters computation. An automatic method is proposed in this research paper for computing road width, road centerline, longitudinal slope and cross slope. Initially, an equation of the line as a best-fit polynomial is used to represent road boundary as connected piecewise linear segments. Further road width and road centerline are computed. MLS data points at road boundary and road centerline are used to compute road slopes. The root mean square error of 2.1%, 2.5%, and 2.2% for longitudinal slope, cross slope (left lane), and cross slope (right lane), respectively were obtained. Proposed method works efficiently on the MLS data points of complex and heterogeneous roadway scene.

The Fortress of Riolo Terme, near Ravenna: digital survey and 3D printing for cultural dissemination

In this work, initially developed as a thesis project, it has been studied the management of the different information methods, derived from the 3D laser scanner survey, of the Fortress of Riolo Terme, near Ravenna, Italy. After studying the building and its history this type of survey has been chosen because of its fast acquisition of three-dimensional data, with the advantage of a level of details and a resolution impossible to be reached by other methods. The geometrical survey of the whole fortress and its surroundings has been enriched by the gathering of color information: taking a specific set of photos for every station, each single scan has been associated to a panoramic image, obtaining a point clouds provided with the corresponding color values.Given the complexity and articulation of the building part of the project was dedicated to the work program, in terms of the decimation of the data, balancing a fluid management of the vast amount of collected data, and the conservation of the appropriate resolution of the information. This brought to the creation of an automatism both for the alignment of the scans, and for the following graphic post-processing. In addition to the production of drawings as plans, elevations and sections, whose outlining has been automated by creating several procedures for Autodesk AutoCAD, a specific part of the project was aimed at the construction of an optimized model of a portion of the building, to be printed out using 3D technology.The project allowed investigating thoroughly an architectural complex that is an outcome of stratifications over time, from the XIV century until the contemporary age. The chosen approach and the type of products elaborated are part of a renovation project for the enjoyment and historical knowledge of the building, which was the primary aim of this work.

3D MODELS OF OBJECTS IN PROCESS OF RECONSTRUCTION

<jats:p>Within the last years terrestrial and airborne laser scanning has become a powerful technique for fast and efficient three-dimensional data acquisition of different kinds of objects. Airborne laser system (LiDAR) collects accurate georeferenced data of extremely large areas very quickly while the terrestrial laser scanner produces dense and geometrically accurate data. The combination of these two segments of laser scanning provides different areas of application. One of the applications is in the process of reconstruction of objects. Objects recorded with laser scanning technology and transferred into the final model represent the basis for building an object as it was original. In this paper, there will be shown two case studies based on usage of airborne and terrestrial laser scanning and processing of the data collected by them.</jats:p>

The use of the model for determining potato (Solanum tuberosum L.) tuber distribution in the soil

The paper focuses on the testing of a model for determining the distribution of potato tubers in the soil. Analytical testing of the model was performed at the laboratory of the Biotechnological Faculty (University in Ljubljana) in 2015 and in the same year, the model was tested in practice on a field owned by the company Zeleni Hit d.o.o. in Ljubljana. After the laboratory testing, the results were analyzed and additional steps were taken to expedite field measurements. To optimize the determination of the distribution of potato tubers in the soil, the program was upgraded to include three-dimensional data acquisition. This allows accurate determination of the horizontal, vertical and longitudinal spans of the distribution of tubers in the soil. Specifically, the program calculates the shape of the tubers, vertical cover of tubers with soil and their minimum distance from the left and right edges of the ridge. The program also locates the center of the tubers, which is a key parameter (along with tuber mass) for determining the area of the tuber cluster. The laboratory testing of the model revealed successful data processing of the program and adequate precision analytics. The testing of the model in the field on Arizona potato variety revealed that the model includes all the data necessary for further processing. Based on the calculated data, it can be assumed with great certainty that the model enables the acquisition of all necessary data and accurately determines the distribution of potato tubers in the soil, ideal shape of the ridge and the minimum necessary depth and distance for the planting of Arizona seed potatoes.

Application progress of digital technology in auricle reconstruction

To review the application progress of digital technology in auricle reconstruction. The recently published literature concerning the application of digital technology in auricle reconstruction was extensively consulted, the main technology and its specific application areas were reviewed. Application of digital technology represented by three-dimensional (3D) data acquisition, 3D reconstruction, and 3D printing is an important developing trend of auricle reconstruction. It can precisely guide auricle reconstruction through fabricating digital ear model, auricular guide plate, and costal cartilage imaging. Digital technology can improve effectiveness and decrease surgical trauma in auricle reconstruction. 3D bioprinting of ear cartilage future has bright prospect and needs to be further researched.

Three-dimensional Ultrasound Elasticity Imaging on an Automated Breast Volume Scanning System.

Ultrasound elasticity imaging has demonstrated utility in breast imaging, but it is typically performed with handheld transducers and two-dimensional imaging. Two-dimensional (2D) elastography images tissue stiffness of only a plane and hence suffers from errors due to out-of-plane motion, whereas three-dimensional (3D) data acquisition and motion tracking can be used to track out-of-plane motion that is lost in 2D elastography systems. A commercially available automated breast volume scanning system that acquires 3D ultrasound data with precisely controlled elevational movement of the 1D array ultrasound transducer was employed in this study. A hybrid guided 3D motion-tracking algorithm was developed that first estimated the displacements in one plane using a modified quality-guided search method, and then performed an elevational guided-search for displacement estimation in adjacent planes. To assess the performance of the method, 3D radiofrequency echo data were acquired with this system from a phantom and from an in vivo human breast. For both experiments, the axial displacement fields were smooth and high cross-correlation coefficients were obtained in most of the tracking region. The motion-tracking performance of the new method was compared with a correlation-based exhaustive-search method. For all motion-tracking volume pairs, the average motion-compensated cross-correlation values obtained by the guided-search motion-tracking method were equivalent to those by the exhaustive-search method, and the computation time was about a factor of 10 lesser. Therefore, the proposed 3D ultrasound elasticity imaging method was a more efficient approach to produce a high quality of 3D ultrasound strain image.

PET/CT scanning with 3D acquisition is feasible for quantifying myocardial blood flow when diagnosing coronary artery disease

BackgroundThe quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are useful approaches for evaluating the functional severity of coronary artery disease (CAD). 15O-water positron emission tomography (PET) is considered the gold standard method for MBF quantification. However, MBF measurements in 15O-water PET with three-dimensional (3D) data acquisition, attenuation correction using computed tomography (CT), and time of flight have not been investigated in detail or validated. We conducted this study to evaluate the diagnostic potential of MBF measurements using PET/CT for a comparison of a control group and patients suspected of having CAD.ResultsTwenty-four patients with known or suspected CAD and eight age-matched healthy volunteers underwent rest and pharmacological stress perfusion studies with 15O-water PET/CT. The whole and three regional (left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) territory) MBF values were estimated. The CFR was computed as the ratio of the MBF during adenosine triphosphate-induced stress to the MBF at rest. The inter-observer variability was assessed by two independent observers. PET/CT using a 15O-water dose of 500 MBq and 3D data acquisition showed good image quality. A strong inter-observer correlation was detected in both the whole MBF analysis and the regional analysis with high intra-class correlation coefficients (r > 0.90, p < 0.001). Regional MBF at rest (LAD, 0.82 ± 0.15 ml/min/g; LCX, 0.83 ± 0.17 ml/min/g; RCA, 0.71 ± 0.20 ml/min/g; p = 0.74), MBF at stress (LAD, 3.77 ± 1.00 ml/min/g; LCX, 3.56 ± 1.01 ml/min/g; RCA, 3.27 ± 1.04 ml/min/g; p = 0.62), and CFR (LAD, 4.64 ± 0.90; LCX, 4.30 ± 0.64; RCA, 4.64 ± 0.96; p = 0.66) of the healthy volunteers showed no significant difference among the three regions. The global CFR of the patients was significantly lower than that of the volunteers (2.75 ± 0.81 vs. 4.54 ± 0.66, p = 0.0002). The regional analysis of the patients demonstrated that the CFR tended to be lower in the stenotic region compared to the non-stenotic region (2.43 ± 0.81 vs. 2.95 ± 0.92, p = 0.052).Conclusions15O-water PET/CT with 3D data acquisition can be reliably used for the quantification of functional MBF and CFR in CAD patients.

Toward a virtual reconstruction of an antique three-dimensional marble puzzle

The reconstruction of broken objects is an important field of research for many applications, such as art restoration, surgery, forensics, and solving puzzles. In archaeology, the reconstruction of broken artifacts is a very time-consuming task due to the handling of fractured objects, which are generally fragile. However, it can now be supported by three-dimensional (3-D) data acquisition devices and computer processing. Those techniques are very useful in this domain because they allow the remote handling of very accurate models of fragile parts, they permit the extensive testing of reconstruction solutions, and they provide access to the parts for the entire research community. An interesting problem has recently been proposed by archaeologists in the form of a huge puzzle composed of a thousand fragments of Pentelic marble of different sizes found in Autun (France), and all attempts to reconstruct the puzzle during the last two centuries have failed. Archaeologists are sure that some fragments are missing and that some of the ones we have come from different slabs. We propose an inexpensive transportable system for 3-D acquisition setup and a 3-D reconstruction method that is applied to this Roman inscription but is also relevant to other applications.

Rapid Acquisition of 3D Images Using High-resolution Episcopic Microscopy.

High-resolution episcopic microscopic (HREM) technology enables rapid acquisition of high-resolution digital volumetric and three-dimensional (3D) morphometric data. Here, we describe the detailed protocol to image the entire mouse embryo. The protocol consists of four major sections: sample preparation, embedding, image acquisition and finally, 3D visualization. The technology requires specimens to be stained with a fluorescent dye, which can be problematic for large or dense specimens. To overcome this limitation, we have improved the existing protocol to enhance tissue penetration of the dye by pretreating the specimen with a solution containing urea and sodium dodecyl sulfate. The protocol uses only routine laboratory equipment and reagents for easy adaptation in standard laboratory settings. We show that the resulting high-resolution 3D images faithfully recapitulate the detailed morphologic features of the internal organs of mouse embryos, thereby permitting morphometric analyses. Together, we present a detailed and improved protocol using standard laboratory equipment to acquire high-resolution 3D images of small and large sized specimens.

Sensor for In-Motion Continuous 3D Shape Measurement Based on Dual Line-Scan Cameras.

The acquisition of three-dimensional surface data plays an increasingly important role in the industrial sector. Numerous 3D shape measurement techniques have been developed. However, there are still limitations and challenges in fast measurement of large-scale objects or high-speed moving objects. The innovative line scan technology opens up new potentialities owing to the ultra-high resolution and line rate. To this end, a sensor for in-motion continuous 3D shape measurement based on dual line-scan cameras is presented. In this paper, the principle and structure of the sensor are investigated. The image matching strategy is addressed and the matching error is analyzed. The sensor has been verified by experiments and high-quality results are obtained.