Vector Map Research Articles

An Exploratory Vector Field Analysis of Ground Reaction Force During Maximum Sprinting Efforts in Male Soccer Players and Sprinters.

The ability to accelerate and attain high velocities is essential for both individual and team sport athletes. The purpose of this explorative study was to retrospectively analyze the ground reaction force using Statistical Parametric Mapping (SPM) vector field analysis, as traditional scalar analyses often fail to acknowledge the interdependence of force vector components. The ground reaction force vector and the scalar components (i.e., vertical and horizontal force) were analyzed for 28 male sprinters and 24 male soccer players at 8.0 and 8.5 m·s-1, and between 85%, 90%, 95%, and 100% of their maximum velocity. The ground reaction force vector differed predominately during mid-stance and late stance between both groups at 8.0 and 8.5 m·s-1. Within-group analysis also revealed that in both groups, the first ~60% of stance tended to increase in relevance when transitioning to higher sprinting velocities as evident by the increasing {T2} test statistic between adjacent velocity comparisons. Sprinters and soccer player reached their respective maximal sprinting velocity at ~40 m. This exploratory study discusses the potential limitations of scalar analysis and highlights the benefits of incorporating vector field analysis. Although both analysis methods resulted in similar conclusions in our re-analysis, vector field analysis may still enhance the understanding of force application in sprint performance by considering the interdependence of force components. We recommend utilizing vector field analyses alongside traditional methods in sports biomechanics research to ultimately enhance the accuracy of interpretations related to vector data.

Vector Field Heterogeneity as a Novel Omnipolar Mapping Metric for Functional Substrate Characterisation in Scar-related Ventricular Tachycardias

BackgroundVector Field Heterogeneity (VFH) is a novel omnipolar metric to quantify local propagation heterogeneities that may identify functionally critical sites for ablation in scar-related VT. ObjectiveAssess the diagnostic value of VFH to identify abnormal propagation patterns during ventricular substrate mapping and compare VFH in VT isthmus sites (IS), low-voltage bystander (LVA) and normal voltage areas (NVA). MethodsSubstrate maps acquired with a 16-pole grid catheter in patients with scar-related VT were segmented into sites corresponding to IS, LVA and NVA (defined as omnipolar voltages >&<1.5mV) based on corresponding VT activation maps. For each 4×4 electrode-array acquisition, omnipolar-derived vector maps of the directions of electrical propagation were computed offline and a VFH value per clique ranging from 0 (perfect planar wave) to 1 (maximal disorganisation) derived. Results16 patients were studied (56.3% ischemic) evaluating 9 endocardial/7 epicardial substrate maps. VFH metric at IS was 0.57±0.26, LVA 0.52±0.34, NVA 0.16±0.24. VFH at IS was higher (more disorganised) than at LVA (p<0.001). VFH in NVA was significantly lower (i.e. more homogenous) compared to IS and LVA (p<0.001, respectively). Within the isthmus, highest heterogeneity was recorded at entry (0.61±0.24), lowest at exit sites (0.44±0.27). ConclusionVFH mapping identified a significant increase in electrical heterogeneity at IS compared to bystanders with highest heterogeneity at the entrance. Absolute differences were small and substantial overlap between sites were recorded precluding its use as a stand-alone mapping approach. VFH may be integrated in existing mapping strategies as complementary information to support identification of ablation targets.

Binary collision dynamics of immiscible Newtonian and non-Newtonian fluid droplets

This experimental and theoretical study is devoted to the investigation of head-on collisions of two immiscible Newtonian and non-Newtonian droplets. The density of the two droplets is similar, and the viscosity of 0.3% carboxymethyl cellulose droplet is slightly larger than 10 cSt silicone oil. The sizes and relative velocity of the colliding droplets close to the point of impact are measured by means of image processing. The deformed states after the impact and their evolution with time are studied by experimental visualization and the energy evolution with time are discussed by numerical results. The accuracy of the two-dimensional axisymmetric three-phase flow computational model is validated. We study the effects of collisions of non-Newtonian droplets with Newtonian droplets and the subsequent retraction kinetics. Droplet “cannibalization” is commonly observed: after collision and spreading, the droplet retracts rapidly, resulting in a Newtonian droplet wrapping around a non-Newtonian droplet. We show the whole process of droplet collision captured by a high-speed camera and obtain the cloud and velocity vector maps of the droplets by numerical simulation. The droplet wrapping phenomenon is produced by different three-phase interfacial tensions and viscosities. We delineate the different phases of the collision process and discuss the dominant forces in each phase. We calculate the energy evolution of the spreading phase and use it to derive a predictive model for the dimensionless maximum spreading diameter and spreading time.

Vector field heterogeneity as a novel omnipolar mapping metric for functional substrate characterization in scar-related ventricular tachycardias

Abstract Background Identification of functionally critical sites to target for ablation in scar-related VT during substrate mapping remains challenging. Vector Field Heterogeneity (VFH) is a novel omnipolar metric to quantify locally heterogeneous propagation patterns. Objective Assess the diagnostic value of VFH for characterizing abnormal propagation patterns during ventricular substrate mapping and compare between sites of VT isthmus, low voltage bystander areas (LVA) and normal voltage areas (NVA). Methods High-density substrate maps and VT activation maps acquired with a 16-pole grid catheter in patients with scar-related VT were retrospectively reviewed. Based on the VT activation maps with either entrainment and/or VT termination with RF ablation to confirm critical sites, the correlating substrate maps were segmented into sites corresponding to isthmus-site, LVA (omnipolar voltage &amp;lt;1.5mV) and NVA (&amp;gt;1.5mV). To compute the VFH, contact mapping data including all EGMs of each grid-catheter acquisition (16 unipols) was exported and processed offline. From each of the 4×4 electrode array acquisitions, omnipolar-derived vector maps of the directions of electrical propagation for recorded sites were estimated using an orientation-independent cross-clique configuration of 4 adjacent unipols, respectively, resulting in 9 vectors with a spatial resolution of 1.4mm2 each. The angle between each vector and horizontal bipole was assessed and compared between neighbouring vectors using finite differences to derive a VFH value per 2x2 EGM clique as a quantitative metric of local heterogeneity ranging from 0 (perfect planar wave) to 1 (maximal disorganisation - "chaos"). The VFH metric was estimated for each segment of the substrate map and compared against each other. Results Nine patients with scar related VT were included (100% male, age 62±20y, ischemic 66.7%, LVEF 36±16%). On average 3.5 VTs (1-8) were induced per case. Avg. substrate map point count was 3825±3190. Computed median VFH metric at sites corresponding to VT isthmus was 0.58±0.30, LVA bystander 0.47±0.39, NVA sites 0.20±0.34. VFH at isthmus-sites was statistically significant higher (i.e. more disorganised) than at LVA bystander sites (p&amp;lt;0.01). VFH in NVA was significantly lower (i.e. more organised) compared to isthmus and LVA sites (p&amp;lt;0.01, respectively). Median omnipolar voltage at isthmus sites was 0.16±0.27mV compared to LVA bystander 0.22±0.36mV (p=0.0816) and NVA 2.97±3.38mV (p&amp;lt;0.01). Conclusion VFH is a promising novel omnipolar mapping metric for electrical substrate characterisation in scar related VTs. VFH mapping identified a quantifiable and significant increase in electrical heterogeneity at sites corresponding to the critical isthmus compared to LVA bystander and normal voltage sites. VFH may provide new insights in the arrhythmogenicity of scar tissue and support more specific functional mapping strategies to identify targets for ablation without the need to induce VT.

Vector Field Heterogeneity (VFH) as a novel quantitative marker of electrical disarray in Arrhythmogenic CardioMyopathy (ACM) with ventricular tachycardia

Abstract Background ACM is a hereditary condition characterized by fibrofatty infiltration and replacement of cardiac myocytes predominantly presenting with ventricular arrhythmias (VA). Cardiac imaging allows for detailed structural phenotyping of scar patterns in ACM. Yet, there is a lack of tools to objectively quantify the electrical substrate alterations that may enable a more precise identification of critical sites that predispose to VA. Purpose To quantify locally disorganized cardiac electrical propagation wavefronts using the Vector Field Heterogeneity (VFH) metric from high-density multi-electrodes in patients with ACM with VT and compare to healthy controls. Methods High density epicardial substrate maps acquired with a 16-pole grid catheter during SR or RV pacing in patients with ACM with VA, who underwent clinically indicated catheter ablation, were retrospectively reviewed. Patients with structurally normal heart and idiopathic VA with epicardial ablation were analysed as a control group. Unipolar contact mapping data was exported &amp; processed offline. From the 4×4 electrode array EGMs, vector maps of the directions of electrical propagation for recorded sites were computed. The VFH was then computed as a quantitative measure of local heterogeneity of propagation, with higher VFH expected to correlate with sites of (micro)structural tissue alterations. VFH was compared between ACM and control patients as well as at sites of normal, border zone &amp; scar based on omnipolar voltage in ACM patients (&amp;gt;1.5mV, 0.5mV–1.5mV, &amp;lt;0.5mV, respectively). Results 10 patients with ACM (70% male, aged 52 ±18 years, ARVC 70%, biventricular 30%, RVEF 40.7±4.7%, LVEF 66±12%) and 2 patients with structurally normal heart (female, 38 &amp; 61 years) were included. Epicardial maps had an average of 9258 ±5412 EGM points. Median VFH was statistically significantly higher in the ACM cohort compared to control for global maps (0.33±0.33 vs 0.13±0.22, p&amp;lt;0.001) and at sites with voltage &amp;gt;1.5mV (i.e. greater disorganization in ACM, p&amp;lt;0.001). In ACM, assessment of VFH according to omnipolar voltage sites (as a surrogate of scar) showed a quantifiable statistically significant increase in electrical disorganized propagation at sites of lower voltage (&amp;lt;0.5mV, median VFH 0.53±0.36) compared to borderzone (0.5-1.5mV, VFH 0.29±0.41) and normal voltage (&amp;gt;1.5mV, VFH 0.15±0.26), p &amp;lt;0.001 respectively. Conclusion Heterogenous electrical propagation as quantified by VFH is significantly increased in patients with ACM at sites of scar, but importantly also in areas of normal voltages when compared to non-ACM controls, possibly indicating microstructural alterations that are missed in traditional assessments of the arrhythmogenic substrate. Identifying and quantifying disorganized conduction patterns by VFH is a promising new mapping approach that could allow improved substrate characterization. Its diagnostic value to guide ablation therapy is currently being validated.VFH Metric ACM and ControlVFH Map Examples

Gain and loss: reflection on the rapid development of National Wetland Parks in China

Context National Wetland Parks (NWPs) are a unique form of protected areas in China that have experienced a rapid increase in number from zero to more than 900 over the past two decades. Aims We examine the underlying causes of the boom in NWPs and assess their far-reaching ecological and socio-economic impacts. Methods Utilising GIS information and vector maps, we analysed the spatial distribution of pilot and approved NWPs from 2005 to 2019. Document analysis was employed to explore resource-orientated and legal drivers that have prompted the growth of NWPs. Key results China’s NWPs developed in three phases, namely, the exploration phase (2005–2007), the expansion phase (2008–2014) and the normalisation phase (2015–present). The demand for outdoor recreation and improved wetland legislation were the primary facilitators for the growth of NWPs. Conclusions The expansion of NWPs is an important contributor to nature conservation and ecological civilisation, yielding a range of ecological, economic and social benefits. Implications China’s experiences in NWPs offers valuable lessons and implications for global nature conservation. Implementing a long-term management mechanism for NWPs is recommended to enhance the conservation and sustainable use of wetlands.

Rapid diagnosis of the geospatial distribution of intertidal macroalgae using large-scale UAVs

Macroalgae have been used as indicators of the health of coastal ecosystems, they function as sinks of CO2 and are essential contributors to primary production. With the increase in anthropogenic activities, it is crucial to assess the impact of such activities on these ecosystems. As traditional surveying techniques, although accurate, are time-consuming and their area coverage is limited, novel techniques are required to monitor the coverage and diversity of intertidal macroalgae. We propose a methodology using the free-source Semi-Automatic Classification Plugin from QGIS to use UAV and multispectral cameras for the spatiotemporal monitoring of intertidal macroalgae. We also compared the performance of six classifiers: Minimum Distance (MD), Maximum Likelihood (ML), Spectral Angle Mapping (SAM), Multi-Layer Perceptron (MLP), Random Forest (RF) and Support Vector Machine (SVM), for three types of macroalgae classification: general, taxonomical groups and species. As proof of concept, an intertidal rocky shore in a marine protected area (NW Spain) was studied for four months. RF and SVM achieved similar results, with both being recommended for the general (OASVM = 97.4±1.7 and OARF = 98.3±1.7) and taxonomical groups (OASVM = 91.6±1.9 and OARF = 89.2±4.5). SVM and ML were found to be more suitable for species classification (OASVM = 77.4±11.4 and OAML = 74.2±9.7). SAM and MLP provided the least performant species classifiers because of the overlap in the macroalgae spectral signatures. The plugin showed limitations when tuning the input parameters of the MLP classifier and did not let to add a validation dataset. Additionally, we present an open-access GIS web application, Alganat 2000 GIS web, to facilitate the monitoring and management of coastal areas. We conclude that the proposed methodology using the SVM or ML classifiers is an effective tool for assessing intertidal macroalgal assemblages. Its easy and rapid implementation is beneficial for researchers who are not very familiar with coding and machine learning frameworks and reduces the time and cost of fieldwork. As future work, we propose the combination of the multispectral bands with topographic and spectral indices and to research the application of deep learning models to the classification of intertidal macroalgae.

Understanding of the Maritime Future Mentality; Safe E-navigation and Safe Maritime Surface Communication

Developing and changing technology affects all sectors globally. Although it primarily affects information systems digitally, it affects all sectors indirectly. Maritime transport, the most important transportation mode in the world, is affected by technological progress as seafarers, ships, and ports. When used for its intended purpose, the technology employs intelligent and rational solutions based on the logic of identifying previous errors and developing predictions accordingly. Maritime transportation is the movement of ships between ports safely and without harming the environment. The sea is a dynamic surface not previously exposed to fixed effects and is affected by meteorological and environmental conditions. As the international maritime authorities keep pace with technological advancements, they have embraced the e-navigation concept, a digital revolution that is set to transform the industry. This shift to Electronic Navigation requires all operations to be digital, making transmission easier and more efficient. It also mandates uninterrupted and high-quality digital communication with ships' land facilities during the entire voyage. ECDIS, one of the advanced automation technology products used for e-navigation, and the vector map ENC it uses are of great importance. ENC maps are produced with specific standards. S-100, which is described as the latest and most advanced standard, provides sailors with good opportunities for safe navigation and communication. The study has been prepared to explain e-navigation types of equipment, their standards, and how they communicate according to cyber security.

Transforming satellite imagery into vector maps using modified GANs

Vector maps find widespread utility across diverse domains due to their capacity to not only store but also represent discrete data boundaries such as building footprints, disaster impact analysis, digitization, urban planning, location points, transport links, and more. Although extensive research exists on identifying building footprints and road types from satellite imagery, the generation of vector maps from such imagery remains an area with limited exploration. Furthermore, conventional map generation techniques rely on labor-intensive manual feature extraction or rule-based approaches, which impose inherent limitations. To surmount these limitations, we propose a novel method called HPix, which utilizes modified Generative Adversarial Networks (GANs) to generate vector tile map from satellite images. HPix incorporates two hierarchical frameworks: one operating at the global level and the other at the local level, resulting in a comprehensive model. Through empirical evaluations, our proposed approach showcases its effectiveness in producing highly accurate and visually captivating vector tile maps derived from satellite images. We achieved a pixel-level accuracy of 61.04% and an SSIM score of 0.75, outperforming all other existing methods. We further extend our study’s application to include mapping of road intersections and building footprints cluster based on their area. We also show usability of our proposed architecture as a general-purpose solutions in other tasks like edges-to-photo, BW-to-color, or labels-to-street scene. GitHub:https://github.com/aditya-taparia/Satellite-Image-to-Vector-Map.

Commutative Encryption and Reversible Watermarking Algorithm for Vector Maps Based on Virtual Coordinates

The combination of encryption and digital watermarking technologies is an increasingly popular approach to achieve full lifecycle data protection. Recently, reversible data hiding in the encrypted domain (RDHED) has greatly aroused the interest of many scholars. However, the fixed order of first encryption and then watermarking makes these algorithms unsuitable for many applications. Commutative encryption and watermarking (CEW) technology realizes the flexible combination of encryption and watermarking, and suits more applications. However, most existing CEW schemes for vector maps are not reversible and are unsuitable for high-precision maps. To solve this problem, here, we propose a commutative encryption and reversible watermarking (CERW) algorithm for vector maps based on virtual coordinates that are uniformly distributed on the number axis. The CERW algorithm consists of a virtual interval step-based encryption scheme and a coordinate difference-based reversible watermarking scheme. In the encryption scheme, the map coordinates are moved randomly by multiples of virtual interval steps defined as the distance between two adjacent virtual coordinates. In the reversible watermarking scheme, the difference expansion (DE) technique is used to embed the watermark bit into the coordinate difference, computed based on the relative position of a map coordinate in a virtual interval. As the relative position of a map coordinate in a virtual interval remains unchanged during the coordinate scrambling encryption process, the watermarking and encryption operations do not interfere with each other, and commutativity between encryption and watermarking is achieved. The results show that the proposed method has high security, high capacity, and good invisibility. In addition, the algorithm applies not only to polyline and polygon vector data, but also to sparsely distributed point data, which traditional DE watermarking algorithms often fail to watermark.

Synoptic Conditions at Pressure Different Levels for the Dust Storm of May/ 2022 Over Iraq

This study examines the severe dust storm from May 12-16/2022,culminating on May 15, with a comprehensive analysis and explanation. The weather maps from the National Oceanic and Atmospheric Administration (NOAA) and the European Centre for Medium-Range Weather Forecasts (ECMWF) weather maps were used to identify systems and patterns that contributed to the storm's activity, continuity, and tracking as well as maps of pressure compounds and wind vectors in levels 1000 and 850 mbar that appear with the dust state for the same days accompanied by tracking patterns in the middle of the turbosphere 500 mbar to give a comprehensive analytical view of climate conditions at each level of pressure and higher systems supportive of their persistence on the surface. The northwesterly winds are the main factor that carries dust over long distances. The eastern desert in Syria, the Empty Quarter in the Kingdom of Saudi Arabia, the desert of western Iran, and the desert region of western Iraq are among the main sources of dust In its atmosphere. Based on weather maps of the surface and upper levels of storm days, the concentration of dust reached very high levels in Iraq's airspace and surrounding countries, including Egypt, Jordan, Lebanon, Palestine, and Syria. The intensity of the dust gradually decreased as the area was affected by wet westerly winds with relatively low temperatures and a relative increase in wind speeds due to the impact of the study area on the atmospheric decline centered around the Turkish island of Cyprus.

Evaluation of landslides susceptibility in Southeastern Tibet considering seismic sensitivity

Southeastern Tibet features a complex geological environment and a high incidence of earthquakes. Earthquake-induced chain disasters pose a great threat to engineering construction and public safety in this area, and landslides are among the most frequent postearthquake disasters. To investigate the impact of earthquakes on landslides, this study constructed a comprehensive database for landslide susceptibility analysis based on various factors, including elevation, slope, slope direction, distances from roads and rivers, proximity to faults, land use patterns, rainfall patterns, and seismic parameters. By integrating the frequency ratio (FR) model with the analytic hierarchy process (AHP) model, this work delineated landslide susceptibility zones in southeastern Tibet. Subsequently, the susceptibility zoning layer was overlaid with the magnitude sensitivity layer and validated using ROC curve analysis to identify the earthquake magnitudes that exerted the greatest influence on landslides. Finally, by incorporating the distance from earthquake epicentres into our refined model framework, different monitoring levels for landslide susceptibility zoning were established. The AHP results show the relative importance of the landslide-influencing factors in southeastern Tibet can be ranked as follows: elevation, slope direction, distance from road, land use, distance from river, slope, and rainfall. The ROC values of the landslide models with seismic sensitivities of 1, 2 and 3 are 0.876, 0.883 and 0.877, respectively, indicating that earthquakes of magnitude 4 and above have a great influence on landslides in the study area. Through the overlay of the landslide susceptibility zoning map and the vector map of distance from seismic focal points, a correlation with the distance between landslide-prone areas and seismic focal points is identified. Within the extremely high susceptibility area and within 40 km of the focal point, there are 220 landslide points, accounting for approximately 34 % of the total landslides in the study area. Additionally, 133 landslide points are located in the extremely susceptible area and within 40–80 km of the focal point, representing approximately 20 % of the total landslides in the study area. The susceptible areas were assessed based on grades, resulting in the production of 4 maps depicting different levels of monitoring for landslide-prone areas. These maps are valuable tools for implementing landslide disaster prevention measures within the study area.

Cerebroventricular deformation and vector mapping, a topographic visualizer for surgical interventions in pediatric hydrocephalus.

Hydrocephalus is a challenging neurosurgical condition due to nonspecific symptoms and complex brain-fluid pressure dynamics. Typically, the assessment of hydrocephalus in children requires radiographic or invasive pressure monitoring. There is usually a qualitative focus on the ventricular spaces even though stress and shear forces extend across the brain. Here, the authors present an MRI-based vector approach for voxelwise brain and ventricular deformation visualization and analysis. Twenty pediatric patients (mean age 7.7 years, range 6 months-18 years; 14 males) with acute, newly diagnosed hydrocephalus requiring surgical intervention for symptomatic relief were randomly identified after retrospective chart review. Selection criteria included acquisition of both pre- and posttherapy paired 3D T1-weighted volumetric MRI (3D T1-MRI) performed on 3T MRI systems. Both pre- and posttherapy 3D T1-MRI pairs were aligned using image registration, and subsequently, voxelwise nonlinear transformations were performed to derive two exemplary visualizations of compliance: 1) a whole-brain vector map projecting the resulting deformation field on baseline axial imaging; and 2) a 3D heat map projecting the volumetric changes along ventricular boundaries and the brain periphery. The patients underwent the following interventions for treatment of hydrocephalus: endoscopic third ventriculostomy (n = 6); external ventricular drain placement and/or tumor resection (n = 10); or ventriculoperitoneal shunt placement (n = 4). The mean time between pre- and postoperative imaging was 36.5 days. Following intervention, the ventricular volumes decreased significantly (mean pre- and posttherapy volumes of 151.9 cm3 and 82.0 cm3, respectively; p < 0.001, paired t-test). The largest degree of deformation vector changes occurred along the lateral ventricular spaces, relative to the genu and splenium. There was a significant correlation between change in deformation vector magnitudes within the cortical layer and age (p = 0.011, Pearson), as well as between the ventricle size and age (p = 0.014, Pearson), suggesting higher compliance among infants and younger children. This study highlights an approach for deformation analysis and vector mapping that may serve as a topographic visualizer for therapeutic interventions in patients with hydrocephalus. A future study that correlates the degree of cerebroventricular deformation or compliance with intracranial pressures could clarify the potential role of this technique in noninvasive pressure monitoring or in cases of noncompliant ventricles.

A handheld polarimetric imaging device and calibration technique for accurate mapping of terahertz Stokes vectors

In recent years, handheld and portable terahertz instruments have been in rapid development for various applications ranging from non-destructive testing to biomedical imaging and sensing. For instance, we have deployed our Portable Handheld Spectral Reflection (PHASR) Scanners for in vivo full-spectroscopic imaging of skin burns in large animal models in operating room settings. In this paper, we debut the polarimetric version of the PHASR Scanner, and describe a generalized calibration technique to map the spatial and spectral dependence of the Jones matrix of an imaging scanner across its field of view. Our design is based on placement of two orthogonal photoconductive antenna (PCA) detectors separated by a polarizing beam splitter in the PHASR Scanner housing. We show that as few as three independent measurements of a well-characterized polarimetric calibration target are sufficient to determine the polarization state of the incident beam at the sample location, as well as to extract the Jones propagation matrix from the sample location to the detectors. We have tested the accuracy of our scanner by validating polarimetric measurements obtained from a birefringent crystal rotated to various angles, as compared to the theoretically predicted response of the sample. This new version of our PHASR scanner can be used for high-speed imaging and investigation of heterogeneity of polarization-sensitive samples in the field.

A local encryption method for large-scale vector maps based on spatial hierarchical index and 4D hyperchaotic system

With the development of geographic information services, applications based on map data are increasing. Internet and mobile communication technologies have brought great convenience to the distribution, sharing, and acquisition of map data. Unfortunately, it also brings great challenges to protect the security and privacy of confidential map data. Although several encryption algorithms have been developed for map data, most of the existing methods are simple extensions of classical encryption algorithms for text data in cryptography, ignoring special structures and characteristics of geospatial data. Existing methods mainly take the entire map or layers as encryption units, which makes the encryption efficiency for large-scale map data low and limits the ability to perform local and incremental encryption for local areas, making it still challenging to meet the needs of map data in applications, such as autonomous driving. To solve the limitations, a local encryption approach for large-scale vector map data is proposed in this paper considering the structure characteristics of map data. Experiments on map data of different types (including points, lines, and polygons) demonstrate the effectiveness of the proposed method. With local and parallel encryption strategies, the proposed method has higher efficiency compared to available algorithms for large-scale map data.

Efficient Parallel Processing of R-Tree on GPUs

R-tree is an important multi-dimensional data structure widely employed in many applications for storing and querying spatial data. As GPUs emerge as powerful computing hardware platforms, a GPU-based parallel R-tree becomes the key to efficiently port R-tree-related applications to GPUs. However, traditional tree-based data structures can hardly be directly ported to GPUs, and it is also a great challenge to develop highly efficient parallel tree-based data structures on GPUs. The difficulty mostly lies in the design of tree-based data structures and related operations in the context of many-core architecture that can facilitate parallel processing. We summarize our contributions as follows: (i) design a GPU-friendly data structure to store spatial data; (ii) present two parallel R-tree construction algorithms and one parallel R-tree query algorithm that can take the hardware characteristics of GPUs into consideration; and (iii) port the vector map overlay system from CPU to GPU to demonstrate the feasibility of parallel R-tree. Experimental results show that our parallel R-tree on GPU is efficient and practical. Compared with the traditional CPU-based sequential vector map overlay system, our vector map overlay system based on parallel R-tree can achieve nearly 10-fold speedup.

AN METHOD FOR CREATING GEOINFORMATION 3D-MODEL OF AN AERODROME USING A DIGITAL TERRAIN MODEL

The creation of a three-dimensional geoinformation model of aerodrome is considered. An approach is proposed, consisting in supplementing a two-dimensional vector map with the values of the third coordinate, which are calculated using data from a digital terrain model. To implement this approach, the problem of interpolation of a function of two variables with a large number of nodal points is solved. The number of nodes where elevation values are set in a digital terrain model can be several thousand for each dimension. In this case, the use of global interpolation methods, for example, splines, in which function values at all nodal points are used to determine the values of a function at a given point falling into a grid cell, is computationally inefficient, since it requires a lot of machine time. It seems more promising to use a local approach to the interpolation problem. In this approach, the value of the function at an arbitrary point is determined by the values of the function at the nodal points of the grid closest to the specified point. Finite formulas are obtained that do not require solving equations, and allow interpolating functions for cases of linear and smooth approximation. An algorithm and a calculation program have been developed for a regular two-dimensional grid of nodes of a digital terrain model using the publicly available SRTM database. The results of numerical calculations of test cases with a comparison of linear and smooth approximations are presented. Using the proposed approach, a three-dimensional model of the Sochi aerodrome was created to simulate the movement of aircraft on its surface. The proposed approach and the interpolation method can be used to calculate the elevation of given points and to create three-dimensional cartographic models of the earth's surface.

High-speed, long-range and wide-field OCT for in vivo 3D imaging of the oral cavity achieved by a 600 kHz swept source laser.

We report a high-speed, long-range, and wide-field swept-source optical coherence tomography (SS-OCT) system aimed for imaging microstructures and microcirculations in the oral cavity. This system operates at a scan speed of 600 kHz, delivering a wide imaging field of view at 42 × 42 mm2 and a ranging distance of 36 mm. To simultaneously meet the requirements of high speed and long range, it is necessary for the k-clock trigger signal to be generated at its maximum speed, which may induce non-linear phase response in electronic devices due to the excessive k-clock frequency bandwidth, leading to phase errors. To address this challenge, we introduced a concept of electrical dispersion and a global k-clock compensation approach to improve overall performance of the imaging system. Additionally, image distortion in the wide-field imaging mode is also corrected using a method based on distortion vector maps. With this system, we demonstrate comprehensive structural and blood flow imaging of the anterior oral cavity in healthy individuals. The high-speed, long-range, and wide-field SS-OCT system opens new opportunities for comprehensive oral cavity examinations and holds promise as a reliable tool for assessing oral health conditions.

Мониторинг границ биомов суши в глобальном масштабе по данным спутниковых наблюдений

Global climate change leads to the transformation and imbalance of all natural systems, to a change in the boundaries of biomes. In this regard, it became necessary to monitor the boundaries of land biomes and to search for methods for determining the boundaries of biomes, ecotones and their control. The aim of this work is to monitor the boundaries of biomes, and to study the seasonal dynamics of NDVI dispersion. The methodological basis of the study is satellite observations and the NDVI moving dispersion method. The dynamics of the moving dispersion of NDVI biomes and ecotones of the land from 2000 to 2020 is estimated in the work. As a result of research, a raster map of the spatial distribution of NDVI dispersions for various biomes (plant communities) was constructed. The raster map of the dispersion distribution of NDVI vegetation is based on MODIS satellite data (product MCD12C1). It is shown that dispersions of NDVI biomes (zones with a certain type of vegetation) have low values. In the transition zones between biomes in ecotones, the dispersion of NDVI increases significantly. The raster map was compared with a biome vector map. The coincidence of biomes on vector biological maps and raster maps showing dispersions of NDVI was revealed. The main factors determining the boundaries of biomes are the spatial and temporal distribution of temperatures, the greatest changes of which occur in the south of the tundra zone and in the north-boreal forests. Studies of the dynamics of biotemperature in the tundra for the period 2001–2020 years showed a positive trend. The results of the spatial distribution of NDVI dispersions over the seasons of the year (winter, spring, summer, and autumn) give an idea of the dynamics of phenological processes on a global scale.

Towards high‐definition vector map construction based on multi‐sensor integration for intelligent vehicles: Systems and error quantification

AbstractA lightweight, high‐definition vector map (HDVM) enables fully autonomous vehicles. However, the generation of HDVM remains a challenging problem, especially in complex urban scenarios. Moreover, numerous factors in the urban environment can degrade the accuracy of HDVM, necessitating a reliable error quantification. To address these challenges, this paper presents an open‐source and generic HDVM generation pipeline that integrates the global navigation satellite system (GNSS), inertial navigation system (INS), light detection and ranging (LiDAR), and camera. The pipeline begins by extracting semantic information from raw images using the Swin Transformer. The absolute 3D information of semantic objects is then retrieved using depth from the 3D LiDAR, and pose estimation from GNSS/INS integrated navigation system. Vector information (VI), such as lane lines, is extracted from the semantic information to construct the HDVM. To assess the potential error of the HDVM, this paper systematically quantifies the impacts of two key error sources, segmentation and LiDAR‐camera extrinsic parameter error. An error propagation scheme is first formed to illustrate how these errors fundamentally influence the accuracy of the HDVM. The effectiveness of the proposed pipeline is demonstrated through our codeavailable at https://github.com/ebhrz/HDMap. The performance is verified using typical datasets, including indoor garages and complex urban scenarios.