At present, industrial scenes with sparse features and weak textures are widely encountered, and the three-dimensional reconstruction of such scenes is a recognized problem. Pressure pipelines have a wide range of applications in fields such as petroleum engineering, chemical engineering, and hydropower station engineering. However, there is no mature solution for the three-dimensional reconstruction of pressure pipes. The main reason is that the typical scenes in which pressure pipes are found also have relatively few features and textures. Traditional three-dimensional reconstruction algorithms based on feature extraction are largely ineffective for such scenes that are lacking in features. In view of the above problems, this paper proposes an improved interframe registration algorithm based on point cloud fitting with cylinder axis vector constraints. By incorporating geometric feature parameters of a cylindrical pressure pipeline, specifically the axis vector of the cylinder, to constrain the traditional iterative closest point algorithm, the accuracy of point cloud registration can be improved in scenarios lacking features and textures, and some environmental uncertainties can be overcome. Finally, using actual laser point cloud data collected from pressure pipelines, the proposed fitting-based point cloud registration algorithm with cylinder axis vector constraints is tested. The experimental results show that under the same conditions, compared with other open-source point cloud registration algorithms, the proposed method can achieve higher registration accuracy. Moreover, integrating this algorithm into an open-source three-dimensional reconstruction algorithm framework can lead to better reconstruction results.

We present a case of pulmonary venous baffle obstruction in a child with a history of congenitally corrected transposition status post double switch repair. We highlight two forms of volume rendering three-dimensional reconstructions from computed tomographic data which allowed for detailed pre-surgical planning. These reconstructions emphasise the concept of maximizing previously obtained two-dimensional data in a time-efficient and cost-effective manner. The benefits of these reconstructions are reviewed, highlighting the relatively novel virtual dissection reconstruction technique that appeared identical to what the surgeon encountered in the operating theatre. This technique allowed the surgeon to quickly advance a preconceived detailed surgical repair.

This work focuses on the application of nanoindentation measurements and the finite element method for analyzing the mechanical properties of the rostrum of the outstanding driller Cyrtotrachelus buqueti Guer. Nanoindentation tests were carried out to measure the Young's modulus and hardness of the rostrum, with the results for the “dry” samples being 13.886 ± 0.75 and 0.368 ± 0.0445 GPa, respectively. The values for the “fresh” samples showed no clear difference from those of the “dry” ones. Moreover, field observation was conducted to determine the motion behaviors of the rostrum on the weevil. Micro-computed tomography technology was employed to obtain structural information about the rostrum, using 9 µm slices. A real three-dimensional model of the rostrum was created using the MIMICS application. Finally, the mechanical properties of the rostrum were determined by finite element analysis. It was concluded that the rostrum provides an ideal biological template for the design of biocomposite materials and lightweight tube-shaped structures. The properties determined in this study can potentially be applied in different fields, such as in the design of automotive hybrid transmission shafts, helicopter tail drive shafts, robotic arms, and other sandwich structures in aerospace engineering.

The detailed kinetics study of erythrocyte deformability is useful for the early diagnosis of blood diseases and for monitoring the blood rheology. Present solutions for a three-dimensional (3D) reconstruction of erythrocytes has a limited potential. This study aimed to use erythrocyte transmission electron images (ETIs) to evaluate the morphological relationship between adjacent ETIs and generate erythrocytes 3D model. First, ultrathin serial sections of skeletal muscle tissue were obtained using an ultramicrotome. Further, the set of ETIs in a capillary were captured by transmission electron microscopy. The images were aligned by translations and rotations using custom software to optimize the morphological relationship between adjacent ETIs. These coordinate transformations exploit the unique principal axis of inertia of each image to define the body coordinate system and hence provide the means to accurately reconnect the adjacent ETIs. The sum of the distances between the corresponding points on the boundary of adjacent ETIs was minimized and, further, was optimized by using physiological relationship between the adjacent ETIs. The analysis allowed to define precise virtual relationship between the adjacent erythrocytes. Finally, extracted erythrocytes’ cross-section images allowed to generate 3D model of the erythrocytes.

High-pressure die-casting (HPDC) AM50 tensile specimens were used to investigate characteristics of gas pores and its effect on mechanical properties of HPDC AM50 magnesium alloy. Combining microstructure morphology gained from optical microscopy, scanning electron microscopy (SEM), and three-dimensional (3D) reconstruction with the experimental data from uniaxial tensile testing, we pursued the relationship between gas pores and the mechanical properties of HPDC AM50 Mg alloy. Results indicate that comparing with 3D reconstruction models, 2D images like optical metallography images and SEM images have one-sidedness. Furthermore, the size and maximum areal fraction of gas pores have negative effects on the mechanical properties of HPDC AM50 Mg alloy. With increase of the maximum size of gas pores in the specimen, the ultimate tensile strength (UTS) and elongation decrease. In addition, with the maximum areal fraction becoming larger, both the UTS and elongation decrease linearly.

High-pressure die-casting (HPDC) AZ91 tensile specimens were used to investigate characteristics of gas pores and their effects on mechanical properties of HPDC AZ91 magnesium (Mg) alloy. Combining the stereoscopic morphology of gas pores obtained from a three-dimensional (3D) reconstruction technique with the experimental data from uniaxial tensile testing, we worked on finite element simulation to find the relationship between gas pores and the mechanical properties of HPDC AZ91 Mg alloy. Results indicate that the 2D metallography images have one-sidedness. Moreover, gas pores >100 µm in the center region have a remarkable negative influence on the ultimate tensile strength (UTS) and elongation. With an increase in the size of large gas pores in the center region, the UTS and elongation of the material decreases. In addition, the distribution of gas pores in the specimens and the areal fraction of gas pores >100 µm on cross sections can also affect the UTS and elongation to some extent.

Peyer's patches, macroscopic aggregates of lymphoid follicles present throughout the small intestines of humans and other mammals, are considered the gateway through which luminal dietary antigens and microbes are sampled by the mucosal immune system. The cellular make-up of Peyer's patch lymphoid follicles is not only complex, but highly dynamic, as there are at least four major cell types that are known to migrate in response to antigenic stimulation. In an effort to capture the complexity and dynamic nature of this specialized tissue, here we report the three-dimensional (3D) reconstruction of immunofluorescent-labeled mouse Peyer's patch cryosections. The technology that enabled the stacking and linear blending of serial cryosections was a novel macro for Fiji, the open source image-processing package based on ImageJ. By simultaneously labeling cryosections for surface markers CD45R, CD3, and CD11c, we provide a 3D image as well as quantitative measures of B-cell, T-cell, and dendritic cell populations at steady state and following exposure to the mucosal adjuvant cholera toxin.

Osteocytes are surrounded by hard bone matrix, and it has not been possible previously to directly observe the in situ architecture of osteocyte morphology in bone. Electron microscope tomography, however, is a technique that has the unique potential to provide three-dimensional (3D) visualization of cellular ultrastructure. This approach is based on reconstruction of 3D volumes from a tilt series of electron micrographs of cells, and resolution at the nanometer level has been achieved. We applied electron microscope tomography to thick sections of silver-stained osteocytes in bone using a Hitachi H-3000 ultra-high voltage electron microscope equipped with a 360° tilt specimen holder, at an accelerating voltage of 2 MeV. Osteocytes with numerous processes and branches were clearly seen in the serial tilt series acquired from 3-μm-thick sections. Reconstruction of young osteocytes showed the 3D topographic morphology of the cell body and processes at high resolution. This morphological data on osteocytes should provide useful information to those who study osteocyte physiology and the several models used to explain their mechanosensory properties.

A 64-element phased-array echocardiographic transducer mounted on a sliding carriage was used transthoracically in 11 patients with subaortic obstruction caused by various different morphological substrates. The transducer is moved in a plane from the outflow tract to the apex of the heart in steps of 0.5 to 1.3 mm and records a tomographic slice of the heart at each step. Parallel images are recorded at a frame rate of 25–30 images per second and triggered to heart rate and respiration. A complete cardiac cycle is recorded at each level. The images are digitized and stored in the image-processing computer, which reconstructs the anatomic structures of the heart in a three-dimensional format by means of different gray-scales. Good quality echocardiographic pictures were obtained in 10 of the 11 patients and three-dimensional reconstructions were possible in those 10 patients. The technique is able to display the heart in real-time in any desired plane, and in up to five planes simultaneously, without the need to change the position of the transducer on the chest. Thus the best views with which to display the substrate of subaortic stenosis could be selected. The left ventricular outflow tract could also be displayed in a view similiar to the one obtained by the surgeon during operative procedures for resection of the subaortic stenosis through an incision in the aortic root. Image acquisition took three to five minutes, and three-dimensional reconstruction of various cardiac structures took 20–90 minutes. Display of the subaortic area in three-dimensional format may enhance our understanding of cardiac anatomy and identify the different morphological lesions in the left ventricular outflow tract which cause subaortic obstruction.

The application of wide field-of-view detection systems to atom probe experiments emphasizes the importance of careful parameter selection in the tomographic reconstruction of the analyzed volume, as the sensitivity to errors rises steeply with increases in analysis dimensions. In this article, a self-consistent method is presented for the systematic determination of the main reconstruction parameters. In the proposed approach, the compression factor and the field factor are determined using geometrical projections from the desorption images. A three-dimensional Fourier transform is then applied to a series of reconstructions, and after comparing to the known material crystallography, the efficiency of the detector is estimated. The final results demonstrate a significant improvement in the accuracy of the reconstructed volumes.

The Helex Septal Occluder is a new device used to close atrial septal defects via interventional catheterization. In order to study the role of echocardiography during its use, and to describe the morphologic variants of defects suitable for closure with this occluder, we evaluated all patients undergoing intended closure of an atrial septal defect with the Helex occluder. A combination of transthoracic, transesophageal, three-dimensional, and intracardiac echocardiography were used before, during, and after the procedure to characterize anatomy, assess candidacy for closure, guide the device during its deployment, and evaluate results. Among the 60 candidates included in the study, 11 were excluded because of transesophageal echocardiographic and/or catheterization data obtained in the laboratory. Attempts at closure were successful in 46 patients, and unsuccessful in 3. We successfully treated four types of defects. These were defects positioned centrally within the oval fossa with appreciable rims along the entire circumference of the defect, defects with deficient or absent segments of the rim, defects with aneurysm of the primary atrial septum, and defects with multiple fenestrations. Follow-up transthoracic echocardiograms taken at a median of 7 months demonstrated no residual defects in 21, trivial residual defects in 17, and small residual defects in 8 patients. In 20 patients, three-dimensional reconstructions were used to characterize the morphology of the defect and the position of the device. Because transesophageal echocardiography was often limited by acoustic interference from the device, intracardiac echocardiography was utilized in 3 cases to overcome this limitation.

Our recent observation that microtubules (MTs) are required for completion of division (abscission) led us to analyze MT organization during cytokinesis. Although many studies of MTs in sea urchin eggs have been done, computer-aided analysis of optical sections described herein reveals a new MT assemblage, which we call furrow MTs. This assemblage comprises bundles of MTs that lie in the cleavage furrow. Furrow MTs become apparent when the furrow has progressed approximately one-third of the way through the egg and persist to abscission. Furrow MTs are 8–24-µm long and arc across the base of the cleavage furrow. Acetylated tubulin is localized primarily in the furrow suggesting a distinct MT population. Three-dimensional analysis of optical sections suggests that furrow MTs are spatially distinct from midbody and astral MTs.

The development of fruits of blackcurrant (Ribes nigrum) cv. Ben Alder from flower to maturity was studied non-invasively by nuclear magnetic resonance (NMR) microscopy, using attached and detached fruits, and the images were compared with those from low temperature scanning electron microscopy (LTSEM) and conventional resin histology. The NMR images derived from 2-D and 3-D datasets showed the previously unreported growth of arillar tissues to the extent that they almost completely occlude the locular cavity, but LTSEM and resin histology revealed that no fusion occurs between the arillar tissues and the gelatinous sheath surrounding each seed, or between the arillar tissues and the endocarp. The discontinuities between these tissues cause magnetic inhomogenities which result in these structures being clearly resolved by gradient echo imaging sequences. During seed maturation the endosperm changed from high (bright) to low (dark) signal intensity as lipid reserves formed and solidified, whereas the gelatinous sheath had high signal intensity throughout maturation. The high lipid concentration in the seed was manifested by chemical shift effects in the images and the increasing viscosity of the endosperm was reflected in the decrease in spin–lattice (T1) relaxation times. The funiculi, throughout development of seeds, appeared in NMR images with low signal intensity and 3-D surface-rendered reconstructions illustrated the complexity of the spatial array of seeds and funiculi arising from parietal placentas within the loculus. All other vascular tissues in the pericarp and placentas were resolved as a small bright core surrounded by a dark region, within a matrix of moderate signal intensity. Conventional microscopical studies then showed that the bright core discernible by NMR imaging encompassed an entire vascular bundle whereas the darker surrounding region represented small parenchyma cells with pronounced intercellular gas spaces. Other regions of the pericarp which included extremely large parenchyma cells, however, had few intercellular spaces and consequently gave rise to brighter regions of the image.

An efficient method of merging images from electron crystallographic data has been developed that is several orders of magnitude faster than the method of phase shift origin search. The results of this new cross-correlation method are compared with the phase residual in terms of speed, consistency with the phase residual method, and the ease of incorporating symmetry constraints along with the image-to-image merging. The program is further accelerated by a more efficient sorting procedure.