Surface Scanning Method Research Articles

Immersive Photorealistic Three-Dimensional Neurosurgical Anatomy of the Cerebral Arteries: A Photogrammetry-Based Anatomic Study.

Neurosurgeons need a profound knowledge of the surgical anatomy of the cerebral arteries to safely treat patients. This is a challenge because of numerous branches, segments, and tortuosity of the main blood vessels that supply the brain. The objective of this study was to create high-quality three-dimensional (3D) anatomic photorealistic models based on dissections of the brain arterial anatomy and to incorporate this data into a virtual reality (VR) environment. Two formaldehyde-fixed heads were used. The vessels were injected with radiopaque material and colored silicone and latex. Before the dissections, the specimens were computed tomography scanned. Stratigraphical anatomic dissection of the neck and brain was performed to present the relevant vascular anatomy. A simplified surface scanning method using a mobile phone-based photogrammetry application was used, and the data were incorporated into a VR 3D modeling software for post-processing and presentation. Fifteen detailed layered photorealistic and two computed tomography angiography-based 3D models were generated. The models allow manipulation in VR environment with sufficient photographic detail to present the structures of interest. Topographical relevant anatomic structures and landmarks were annotated and uploaded for web-viewing and in VR. Despite that the VR application is a dedicated 3D modeling platform, it provided all necessary tools to be suitable for self-VR study and multiplayer scenarios with several participants in one immersive environment. Cerebral vascular anatomy presented with photogrammetry surface scanning method allows sufficient detail to present individual vessel's course and even small perforating arteries in photorealistic 3D models. These features, including VR visualization, provide new teaching prospects. The whole study was done with simplified algorithms and free or open-source software platforms allowing creation of 3D databases especially useful in cases with limited body donor-based dissection training availability.

Failure analysis of large and complex engine blades based on experimental research

On a certain day in December 2022, a GE90 engine equipped by an airline experienced a surge during flight. Ground inspection revealed broken blades of the 9-stage high-pressure compressor. To identify the cause of its fracture failure, the macroscopic fracture surface was first analyzed. Obvious fatigue crack propagation characteristics were found at the blade cross-section. Small pits formed by the impact were observed at the crack source location, indicating that the blade was first formed into a circular arc-shaped impact wound after being impacted by an external object. In the subsequent service process, under continuous vibration, fatigue cracks are formed at the impact point as the crack source and gradually propagate, ultimately leading to blade fracture and failure. To further explore the source of foreign objects causing impact damage, the surface scanning method using energy spectrum analysis was used. An enriched region of C element was found near the impact point. However, due to the lack of conditions for the formation of C combustion products at the compressor location, it can be considered that the foreign object may have come from external sources.

Body composition in healthy singleton term infants using the three-dimensional photonic scanning method: A multicenter cross-sectional study

ObjectivesBody composition is an integral part of the nutritional assessment during infancy as it is closely related to future health. The three-dimensional photonic body surface scanning (3-DPS) method is a promising new technique for measuring body composition in children because of its advantages of easy operation, low cost, and no exposure to radiation. Using 3-DPS, this study aimed to illustrate the growth trajectories of body composition indicators during infancy according to sex and age. MethodsThis was a multicenter cross-sectional study. The body compositions of 9644 singleton term infants from four centers in Shandong Province, China, were assessed using 3-DPS. The data of 8769 healthy infants (52.0% boys), whose z scores of weight-for-length, length-for-age, and weight-for-age, according to World Health Organization standards, were in the range of –2 to 2, –3 to 3, and –3 to 3, respectively, were sampled to construct percentile curves of fat mass (FM), fat-free mass (FFM), FM percentage (FM%), FM index (FMI), and FFM index (FFMI) with the generalized additive model for location, scale, and shape method. ResultsPercentile charts for FM, FFM, FM%, FMI, and FFMI were developed based on age and sex. FM and FFM presented consistent trajectories with that of weight, with the fastest growth occurring at 1 to 3 mo of age. FM%, FMI, and FFMI increased with age, peaked at 6 mo, and gradually declined, which was consistent with the body mass index trend. All indicators, except for FFMI, were always significantly higher in boys than in girls ages 1 to 12 mo, indicating that sex differences in body composition existed mainly in FM rather than in lean body mass. ConclusionsThe body composition of healthy singleton term infants during infancy varies with age; boys may have more FM accumulation than girls.

3D Surface Scanning-A Novel Protocol to Characterize Virtual Nickel-Titanium Endodontic Instruments.

The nickel-titanium (NiTi) instruments' geometry plays an important role in their performance and behavior. The present assessment intends to validate and test the applicability of a 3D surface scanning method using a high-resolution laboratory-based optical scanner to create reliable virtual models of NiTi instruments. Sixteen instruments were scanned using a 12-megapixel optical 3D scanner, and methodological validation was performed by comparing quantitative and qualitative measurements of specific dimensions and identifying some geometric features of the 3D models with images obtained through scanning electron microscopy. Additionally, the reproducibility of the method was assessed by calculating 2D and 3D parameters of three different instruments twice. The quality of the 3D models created by two different optical scanners and a micro-CT device was compared. The 3D surface scanning method using the high-resolution laboratory-based optical scanner allowed for the creation of reliable and precise virtual models of different NiTi instruments with discrepancies varying from 0.0002 to 0.0182 mm. The reproducibility of measurements performed with this method was high, and the acquired virtual models were adequate for use in in silico experiments, as well as for commercial or educational purposes. The quality of the 3D model obtained using the high-resolution optical scanner was superior to that acquired by micro-CT technology. The ability to superimpose virtual models of scanned instruments and apply them in Finite Element Analysis and educational purposes was also demonstrated.

Airfoil Surface Forming and Conformity Test Using Laser Tracker

In this study, NACA0018 airfoil surface conformity test was conducted using API tracker3 in combination with SpatialAnalyzer (SA) and modeling software SolidWorks. Plaster of Paris is used as a plug making material and a woven-type fiberglass is used as mold and airfoil surface making material. For airfoil surface analysis, three-dimensional model of the airfoil surface was developed in SolidWorks software and imported in IGES file format to SpatialAnalyzer (SA) software. Then, measurements were taken from manufactured airfoil surface using laser tracker through surface scanning method. Surface conformity test was conducted through fitting of measured points to surface model imported from SolidWorks to SpatialAnalyzer (SA) software. The optimized fit summary result shows that the average fit difference is 0.0 having standard deviation from 0.22224 from the average and zero with RMS of 0.2210. The maximum magnitude of the difference including x and y together is 0.5336 and the minimum −0.5077. Thus, with a given range of surface quality specification, laser tracker is an easy and reliable measurement and inspection tool to be considered.

Estimating body segment parameters from three-dimensional human body scans.

Body segment parameters are inputs for a range of applications. Participant-specific estimates of body segment parameters are desirable as this requires fewer prior assumptions and can reduce outcome measurement errors. Commonly used methods for estimating participant-specific body segment parameters are either expensive and out of reach (medical imaging), have many underlying assumptions (geometrical modelling) or are based on a specific subset of a population (regression models). Our objective was to develop a participant-specific 3D scanning and body segmentation method that estimates body segment parameters without any assumptions about the geometry of the body, ethnic background, and gender, is low-cost, fast, and can be readily available. Using a Microsoft Kinect Version 2 camera, we developed a 3D surface scanning protocol that enabled the estimation of participant-specific body segment parameters. To evaluate our system, we performed repeated 3D scans of 21 healthy participants (10 male, 11 female). We used open source tools to segment each body scan into 16 segments (head, torso, abdomen, pelvis, left and right hand, forearm, upper arm, foot, shank and thigh) and wrote custom software to estimate each segment's mass, mass moment of inertia in the three principal orthogonal axes relevant to the center of the segment, longitudinal length, and center of mass. We compared our body segment parameter estimates to those obtained using two comparison methods and found that our system was consistent in estimating total body volume between repeated scans (male p = 0.1194, female p = 0.2240), estimated total body mass without significant differences when compared to our comparison method and a medical scale (male p = 0.8529, female p = 0.6339), and generated consistent and comparable estimates across a range of the body segment parameters of interest. Our work here outlines and provides the code for an inexpensive 3D surface scanning method for estimating a range of participant-specific body segment parameters.

Single-shot high speed aerial chromatic confocal metrology sensor

Chromatic confocal metrology is a widely established optical metrology technique, which allows for noncontact, high-speed three-dimensional surface profiling without the need of mechanical depth scanning. However, current methods are limited by the use of some sort of surface scanning method with mechanically moving parts. Furthermore, the setups involve a spectrometer setup, either through prisms, gratings, or multispectral cameras. This drastically limits the simultaneously measureable positions in lateral direction, as the spectrometer setup will utilize one spatial dimension for the wavelength domain. We present a method for chromatic confocal metrology that enables high-speed and high-resolution one-shot aerial surface metrology. This method is scalable with respect to measurement range in axial as well as in lateral direction and in the number of measurement points that can be measured simultaneously. After deriving the theoretical basis of the approach, a virtual optical design with a field of view of 10 mm × 10 mm and a depth range of 1.5 mm with roughly 1000 measurement points, based mainly on off-the-shelf components will be presented. This virtual system design was used to perform various simulations and explain the design process and considerations as well as the expected system response of the proposed system.

An automated cluster surface scanning method for exploring reaction paths on metal-cluster surfaces

Metal-cluster surfaces present a wide variety of unique coordination environments. This complexity makes it difficult to manually probe the surface reactivity of such clusters. Here, we present a simple and automated method to systematically discover reaction pathways on cluster surfaces, based on the automated cluster surface scanning (ACSS) technique for mapping out potential energy surfaces. We showcase our method on 55-atom icosahedral Cu and Ag clusters, where we determine the activation energies of four elementary steps common in heterogeneous catalysis – hydrogen recombination (H* + H* → H2* + *), oxygen recombination (O* + O* → O2* + *), water formation (OH* + H* → H2O* + *), and CO oxidation (CO* + O* → CO2* + *) – with density functional theory calculations (DFT-PBE + D3). We show that the ACSS method requires significantly less human effort than the established manually performed climbing-image nudged elastic band (MP + CI-NEB) technique and locates transition states with comparable accuracy (root-mean-squared error of 0.10 eV) and similar computational cost. Rigorous sampling of the potential energy surface with the ACSS method allows one to locate all lowest-energy reaction pathways obtained via the MP+CI-NEB approach, as well as alternative pathways that one may have missed with the MP+CI-NEB approach due to the many possible pathways available on these clusters. The accuracy and efficiency afforded by the ACSS method could enable high-throughput exploration of the diverse reactivity of metal clusters.

A new cutting edge surface reconstruction method for hard whirling tools

Edge surface reconstruction is the prerequisite for evaluating the quality of cutting edge preparation. However, accurate modelling for edge surface has great challenge in terms of accuracy and efficiency. This paper aims to develop a new method to solve this problem. The proposed method uses laser scanning confocal microscope to obtain the selected section data and introduces fractal interpolation to reconstruct the edge. To ensure the accuracy, the transition point identification method based on approximate curvature difference is presented. A novel data flattening process is also performed to avoid shape copying. Results show that the edge radius fitted with the points in the transition zone is close to the experimental value. Data flattening prevents the shape between interpolation points copying the edge macroshape. The proposed reconstruction method takes much less time than the surface scanning method, and its measurement accuracy is higher than that of the coordinate measuring machine method.

The consistency of an optical body surface scanning method compared with computed tomography: a validation study

ObjectiveThe ideal noninvasive method for evaluation of pectus excavatum remains to be defined. We sought to verify the accuracy of an optical body surface scanning method compared with conventional CT scan. Materials and methodsA PrimeSense 3D sensor was used to obtain data from patients undergoing surgical or noninvasive treatment for pectus excavatum. The Haller index, external Haller index, and depth ratio were then calculated from both body scan and computed tomography scan data for the same patients. Statistical analyses were carried out to find if there is consistency between data from body scanning and computed tomography. ResultsData acquisition was complete. In total, 40 patients (median age: 5.03 years, 11 female) with pectus excavatum undergoing nonoperative (n = 13) or surgical Nuss treatment (n = 27) were included. The Haller index was lower in vacuum bell patients, which also had a higher female proportion. Pearson correlation coefficient between external Haller indices from body scanning and from computed tomography and between the depth ratios from body scanning and from computed tomography were 0.63 and 0.84, respectively. By intraclass correlation coefficient method, the correlation coefficient was 0.56 between external Haller indices from body scanning and from computed tomography and 0.80 between depth ratios from body scanning and from computed tomography. ConclusionThe optical body surface scanning is a reliable approach to the measurement of PE severity and could be routinely used in the monitoring of PE development of treatment, especially in the pediatric population. Study typeDiagnostic test. Level of evidenceLevel II.

Characteristics of a dynamic atomic force microscopy based on a higher-order resonant silicon cantilever and experiments

Abstract In order to improve the sensitivity and scanning speed of the dynamic AFM, a surface scanning method using higher-order resonant cantilever is adopted and investigated based on the higher-order resonance characteristics of the silicon cantilever, and the theoretical analysis and experimental verification on the higher-order resonance characteristics of the corresponding dynamic AFM cantilever are given. In this method, the cantilever is excited to oscillate near to its higher-order resonant frequency which is several times higher than that of the fundamental mode. Then the characteristic changes a lot compared with the first-order resonant cantilever. Because of the changes of the quality factor, amplitude and the mode shape of the cantilever, the higher-order resonant AFM gets higher sensitivity and scanning speed. Based on the home-built tapping-mode AFM experiment system, the resolution and the response time of the first and second order resonance measured by experiment are respectively: 0.83 nm, 0.42 nm; 1265 μs, 573 μs. The higher-order resonance cantilever has higher sensitivity and the dynamic measurement performance of the cantilever is significantly improved from the experimental results. This can be a useful method to develop AFM with high speed and high sensitivity. Besides above, the surface profile of a grating sample and its three-dimensional topography are obtained by the higher-order resonant mode AFM.

Reconstruction of real tooth surfaces of spiral bevel pinions with modified offset

Reverse engineering has been successfully applied in many fields; however, it is not the case for spiral bevel gears. In order to reconstruct the real tooth surfaces of spiral bevel pinions based on the original tooth surface grids (OTSG) provided by coordinate measuring machine, meshing performances were achieved by tooth surface scanning method. Three meshing conditions necessary for local synthesis, i.e. the directional angle, the magnitude of major axis of contact ellipse and the second derivative of transmission errors at the mean contact point, were filtered from the meshing performances obtained by discrete tooth contact analysis. Computational tooth surface grids (CTSG), corresponding to OTSG node to node, were expressed by manufacturing parameters derived by local synthesis. Tooth surface grid difference was formed by making the centre node of CTSG through rotation operation coincided with that of OTSG. Optimization objective was built up by summing up the deviations of all nodes on either OTSG or CTSG. The three meshing conditions, the mean contact point position and the higher order coefficients of blank offset correction were taken as the design variables. The internal function fminsearch of MATLAB was chosen to minimize the tooth surface grid difference. After the manufacturing parameters were achieved, the pinion tooth surfaces were reconstructed based on the reversed CTSG. A zerol spiral bevel pinion in an aviation engine accessory gear box was employed to demonstrate the proposed methodology. The results show that OTSG is unable to give perfect meshing performance. The convergent results of reversing show that many of the field of distance between the reversed CTSG and OTSG is less than 1 μm. This demonstrates the feasibility of the proposed reversing techniques.

Pyroelectric scanning probe microscopy: A method for local measurement of the pyroelectric effect in ferroelectric thin films

This work demonstrates a surface scanning method for the quantitative determination of the local pyroelectric coefficient in ferroelectric thin films. It allows generating a map of the pyroelectric response with very high spatial resolution. In domains of previously aligned dipole moments (achieved by tip-assisted poling) small heat fluctuations are achieved by laser diode excitation from the sample's bottom side thus inducing changes in the surface potential due to the pyroelectric effect. Simultaneously, the surface potential variations are detected by scanning surface potential microscopy thus forming the base for the pyroelectric coefficient map. The potential of the method is demonstrated on the basis of ferroelectric semicrystalline copolymer thin films yielding local maxima of the pyroelectric coefficients up to $40\text{ }\ensuremath{\mu}\text{C}/{\text{m}}^{2}\text{ }\text{K}$. Another promising feature is the ability to visualize ``screened'' polarization thus enabling in-depth profiling of polarization distributions and domain formation and to study the composition dependence of ferroelectric nanodomains.

Detection of laser induced dielectric breakdown in water using a laser doppler vibrometer

Abstract This study is focused on exploring the feasibility of an all-optic surface scanning method in determining the size and position of a submerged, laser generated, optoacoustic (OA) source. The optoacoustic effect in this case was generated when the absorption of a short electromagnetic pulse in matter caused a dielectric breakdown, a plasma emission flash and a subsequent acoustic wave. In the experiment, a laser pulse with λ = 1064 nm and 12 ns pulse length was aimed at a volume of deionized water. When the laser beam was focused by a f = 16 mm lens, a single dielectric breakdown spot occurred. When a f = 40 mm was used several breakdowns in a row were induced. The breakdowns were photographed using a double shutter camera. The acoustic wave generated by the dielectric breakdowns were detected at a point on the water surface using a laser Doppler vibrometer (LDV). First, the LDV signal was used to calculate the speed of sound with an accuracy of 10 m/s. Secondly, the location and length of the dielectric breakdown was calculated with an accuracy of 1 mm. The calculated position matched the breakdown location recorded by a camera. The results show that it is possible to use LDV surface measurements from a single spot to determine both the position and length of the OA source as well as the speed of sound in the medium. Furthermore, the LDV measurements also show a secondary peak that originates from the OA source. To unravel the origin and properties of this interesting feature, further investigations are necessary

Enhancing accuracy in magneto-and electroencephalography focal source localization

This paper investigates the origins of localization errors when cortically distributed source approach is applied to magnetoencephalography (MEG) and electroencephalography (EEG) focal source reconstruction problems. It was revealed from simulations that the errors mainly stem from 1)Asymmetric distribution of crosstalk and 2)Large noises at some time slices. To enhance the localization accuracy, a new algorithm named cortical surface scanning (CSS) method is presented. The proposed algorithm was applied to realistic simulations and more accurate and robust source estimates could be obtained.

Contributions to in-plane piezoresponse on axially symmetrical samples

We report on the influence of system-immanent asymmetries on the interpretation of in-plane piezoresponse force microscopy (PFM). As PFM is a surface scanning method, the electromechanical interaction of probe tip and sample is a key aspect of all experiments. An initial characterization of topography, surface state, and conductivity is mandatory to separate their signal from the response due to an in-plane polarization state. Our findings underline that any reduction of radial symmetry in the tip-sample system creates an otherwise symmetry-prohibited in-plane signal.

Electronic Videoendoscopic Laryngostroboscopy

Color images obtained using electronic videoendoscopic laryngostroboscopy (EVLS) were presented and the utility of this technique for the diagnosis of dysphonia was discussed in this paper. Stroboscopic evaluations of laryngeal lesions were performed using a rhinolaryngeal electronic videoendoscope system employing a single-plate simultaneous color charge-coupled device (CCD) chip method. Twenty patients underwent electronic videoendoscopic laryngostroboscopy. A Karl Storz laryngostroboscope Pulsar was connected to this system and laryngeal lesions were assessed. The potentialities of laryngostroboscopy using this system were evaluated. Clear stroboscopic images were obtained in all patients. Multiple still images during vocal fold vibration were acquired using an optional function. The laryngostroboscope is not compatible with conventional systems employing a single-plate red, green, and blue (RGB) surface scanning method. However, the system used was successfully connected to a laryngostroboscope. EVLS appears to be a powerful new tool for the diagnosis of dysphonia.

電子内視鏡システムを用いた咽喉頭の観察

Electronic videoendoscopy of the pharynx and larynx allows lesions to be visualized with precision. The images obtained using a charge-coupled device (CCD) chip are converted into electric signals and transmitted to the video system center. Clear, dynamic color images are reproduced on a color video monitor through a video system center. The basic components of an electronic videoendoscope system are a flexible endoscope, a video system center, a light source and a color video monitor.There are two methods of capturing and reproducing dynamic color images in electronic videoendoscopy; the single-plate simultaneous color CCD chip method and the single-plate red, green, and blue (RGB) surface scanning method. In the former method, a color CCD chip built into the distal tip of the endoscope contains multiple color pixels and can simultaneously capture different color wavelength of light. In the latter method, the tip of the endoscope incorporates a monochrome CCD chip that can only provide black and white signals. The color CCD chip simplifies color acquisition but is considerably larger than the monochrome CCD chip, requiring a wider diameter than the distal tip of the endoscope. This is one of the reasons why the single-plate RGB surface scanning method is preferred in a rhinolaryngeal electronic videoendoscope system.Digital image processing of lesions can be performed by electronic videoendoscopy. The enhanced color images are superior in quality.Laryngostroboscopy is the most practical method of determining the vibratory pattern of the vocal folds during phonation. However, the laryngostroboscope cannot connect with the electronic videoendoscope system using a single-plate RGB scanning method because of the presence of a rotating wheel filter between the light source and glass fiber bundle of the light guide. To obtain stroboscopic images with an electronic videoendoscope system, a single-plate simultaneous color CCD chip method is necessary.Recent advances in electronic technology enables production of the electronic videoendoscope system that can connect with a laryngostroboscope. The clear stroboscopic images of vocal fold vibration obtained by this system are described here.Literature reviews of the history and development of electronic videoendoscopy were also performed from the perspective of diagnostic usefulness.

Line Focus Method for Recording Laser Raman Spectra of Colored Solids

The problems caused by the local overheating of colored Raman samples when illuminated by a focused laser beam have been circumvented in the and methods by introducing a fast relative motion between the sample and the incident radiation which results in a very short stay of the sample molecules in the laser beam at any given instance. In the rotating cell method the sample cell is rotated while in the surface scanning method the point of incidence of the focused laser beam on the sample surface is moved by rotating an optical component (a refractor plate or the focusing lens) between the laser and the sample. Thus, both methods require a rotating device. Here we report a simple modification of the ordinary Raman scattering setup which has enabled us to obtain Raman spectra of colored solids and does not require any moving parts.