Geometry Data Research Articles

Manifold Harmonics and Their Application to Computational Electromagnetics

The eigenfunctions of the Laplace-Beltrami operator (LBO), or manifold harmonic basis (MHB), have many applications in mathematical physics, differential geometry, machine learning, and topological data analysis. MHB allows us to associate a frequency spectrum to a function on a manifold, analogous to the Fourier decomposition. This insight can be used to build a framework for analysis. The purpose of this paper is to review and illustrate such possibilities for computational electromagnetics as well as chart a potential path forward. To this end, we introduce three features of MHB: (a) enrichment for analysis of multiply connected domains, (b) local enrichment (L-MHB) and (c) hierarchical MHB (H-MHB) for reuse of data from coarser to fine geometry discretizations. Several results highlighting the efficacy of these methods are presented.

A theoretical study of CO adsorption on Cu(211) surface with coverage effects.

CO adsorption on the Cu(211) surface was investigated using energy, geometry and vibrational data, which were produced through periodic DFT computations. Adsorption on the (111) terrace, as well as the previously reported top and bridge sites of the step-edges, was studied at 0.25, 0.33, 0.50, 0.66, 0.75, and 1.00 monolayer (ML) CO coverage. Results showed that up to and including 0.50 ML, on-top or bridge adsorption is preferred on the step-edges. When 0.50 ML is exceeded, top-bridge alternating patterns become feasible on the step edges along with possible shifts towards the terrace. Several feasible patterns were identified at 0.66, 0.75, and 1.00 ML. Like step-edge adsorptions, alternating patterns on the terrace sites were found feasible at higher coverages. For all the studied cases, highest adsorption energies were found for the step-edge positions. In general, coordination number had a stronger effect than coverage on the calculated properties.

Vision-Based Localization in Multi-Agent Networks With Communication Constraints

Among the diversified applications of Internet of Vehicles (IoV), vision-based localization has raised increasing concern for its extraordinary performance in terms of accuracy and flexibility. The ultra-reliability and low-latency requirements of IoV have posed urgent demand for the provision of precise relative network geometry and efficient data transmission. In this paper, we propose a vision-based relative localization scheme in the presence of communication constraints. First, the relative squared position error bound (SPEB) is derived via subspace projection of the Fisher information matrix. Next, we determine the local convexity of the relative SPEB with respect to bit allocation vectors and propose two bit allocation algorithms. Furthermore, we exploit the vision-based relative geometry and develop two localization algorithms based on Euclidean distance matrix completion. The simulation results validate that the proposed vision-based localization algorithms achieve near-optimal performance in terms of the relative SPEB under bandwidth constraints, as well as demonstrate the superiority of adopting cooperation among mobile agents.

Risk based assessment of corroded oil drilling rig pipe integrity and remaining life

Risk based assessment of structural integrity of corroded oil drilling pipe is presented and applied on prototype (welded pressure vessel made of pipe) with artificial defects, which was previously investigated under service (10 MPa) and testing (22 MPa) pressure. The new concept based on application of structural integrity estimation to assess risk level according to probability and consequence of failure was used. Probability of failure is taken as the ratio of the service point, estimated by using the basic linear elastic fracture mechanics concept, and point on limit line in the Failure Analysis Diagramme (FAD). Taking into account measure of probability and consequence, the risk matrix is made for the round defect in a new pipe, 1.75 mm (depth) x 26 mm (length), service and testing pressure. Results are also compared with the previous ones for defects 3.5 × 28 mm and 5.25 × 30 mm. These results are useful for managers to make decision about further use of damaged pipes, based on data provided by engineers. The procedure for risk assessment of structural integrity is a general one, applicable to any component with known geometry, including crack, material properties and loading data, as well as to the structural life assessment.

Metodika získavania vonkajšej geometrie segmentov novej generácie skúšobnej figuríny

The article presents the fulfilment of a partial goal of the research project focused on developing and constructing a biofidelic surrogate of the human body to improve the forensic reconstruction of road traffic accidents. It aims to describe the methods and results of acquiring external geometry of segments of crash test dummy Hybrid III. To create a precise spatial representation of dummy segments, we applied 3D laser scanning using the handheld 3D scanner VIUscan Handyscan 3D. The workflow, used material and application of software support are closely described in the methodical part of the article. The results present 3D models of significant material for the continuous fulfilment of project goals. In the follow-up activities, we will use dummy external geometry data, particularly to develop molds for casting segments of new-generation synthetic human body surrogates.

The Design of an Automatic Flight Control System and Dynamic Simulation for Fixed-Wing Unmanned Aerial Vehicle (UAV) using X-Plane and LabVIEW

This research focuses on developing an automatic flight control system for a fixed-wing unmanned aerial vehicle (UAV) using a software-in-the-loop method in which the PID controller is implemented in National Instruments LabVIEW software and the flight dynamics of the fixed-wing UAV are simulated using the X-Plane flight simulator. The fixed-wing UAV model is created using the Plane Maker software and is based on existing geometry and propulsion data from the literature. Gain tuning for the PID controller is accomplished using the pole placement technique. In this approach, the controller gain can be calculated using the dynamic parameters in the transfer function model and the desired characteristic equation. The proposed controller designs' performance is validated using attitude, altitude, and velocity hold simulations. The results demonstrate that the technique can be an effective tool for researchers to validate their UAV control algorithms by utilising the realistic UAV or manned aircraft models available in the X-Plane flight simulator.

Vortex Trapping Cavity on Airfoil: High-Order Penalized Vortex Method Numerical Simulation and Water Tunnel Experimental Investigation

This paper presents a two-dimensional implementation of the high-order penalized vortex in cell method applied to solve the flow past an airfoil with a vortex trapping cavity operating under moderate Reynolds number. The purpose of this article is to investigate the fundamentals of the vortex trapping cavity. The first part of the paper treats with the numerical implementation of the method and high-order schemes incorporated into the algorithm. Poisson, stream-velocity, advection, and diffusion equations were solved. The derivation, finite difference formulation, Lagrangian particle remeshing procedure, and accuracy tests were shown. Flow past complex geometries was possible through the penalization method. A procedure description for preparing geometry data was included. The entire methodology was tested with flow past impulsively started cylinder for three Reynolds numbers: 550, 3000, 9500. Drag coefficient, streamlines, and vorticity contours were checked against results obtained by other authors. Afterwards, simulations and experimental results are presented for a standard airfoil and those equipped with a trapping vortex cavity. Airfoil with an optimized cavity shape was tested under three angles of attack: 3°, 6°, 9°. The Reynolds number is equal to Re = 2 × 104. Apart from performing flow analysis, drag and lift coefficients for different shapes were measured to assess the effect of vortex trapping cavity on aerodynamic performance. Flow patterns were compared against ultraviolet dye visualizations obtained from the water tunnel experiment.

Foids

We present a bio-inspired fish simulation platform, which we call "Foids", to generate realistic synthetic datasets for an use in computer vision algorithm training. This is a first-of-its-kind synthetic dataset platform for fish, which generates all the 3D scenes just with a simulation. One of the major challenges in deep learning based computer vision is the preparation of the annotated dataset. It is already hard to collect a good quality video dataset with enough variations; moreover, it is a painful process to annotate a sufficiently large video dataset frame by frame. This is especially true when it comes to a fish dataset because it is difficult to set up a camera underwater and the number of fish (target objects) in the scene can range up to 30,000 in a fish cage on a fish farm. All of these fish need to be annotated with labels such as a bounding box or silhouette, which can take hours to complete manually, even for only a few minutes of video. We solve this challenge by introducing a realistic synthetic dataset generation platform that incorporates details of biology and ecology studied in the aquaculture field. Because it is a simulated scene, it is easy to generate the scene data with annotation labels from the 3D mesh geometry data and transformation matrix. To this end, we develop an automated fish counting system utilizing the part of synthetic dataset that shows comparable counting accuracy to human eyes, which reduces the time compared to the manual process, and reduces physical injuries sustained by the fish.

DAMPAK PEMBANGUNAN PINTU TOL JATIKARYA TERHADAP KINERJA SIMPANG 4 KRANGGAN

Kranggan intersection in Cibubur City is an intersection with four arms equipped with traffic light signals. Kranggan intersection is the confluence of four roads, namely Jl. Kranggan, Jl. Raya Kalimanggis Jl. Transyogi Barat, and Jl. Transyogi East. This intersection has a condition where long queues often occur at this intersection. especially after the existence of the Jatikarya toll gate, the behavior of the Kranggan 4 intersection has changed the direction of traffic flow, of course, so it is necessary to study how many changes have occurred. The research method used is a quantitative method by collecting road geometric data, intersection geometry and current traffic data in 2021 through direct surveys at the research location as well as traffic data on the Alternative Cibubur (Transyogi) road.Before the existence of the Jatikarya toll gate, it was known that the degrees of saturation for the north and west approaches were 0.80, 1.04 (ds > 0.75 ; saturated), while the south and east approaches produced a degree of saturation (ds) of 0.16 respectively. , 0.30 (ds < 0.75 ; unsaturated). The highest queue length is 387.82 m, the average delay of the resulting intersection is 51.47 sec/pcu and the level of service (LOS) is entered with level E (40-60 sec/pcu). After the presence of the Jatikarya toll gate, it is known that the degree of saturation for the South approach is 0.81 (ds > 0.75 ; saturated), while the North, East and West approaches produce degrees of saturation (ds) of 0.56, 0.11 respectively. , 0.38 (ds < 0.75 ; unsaturated). The highest queue length is 167.87 m, the average delay of the resulting intersection is 13, 72 sec/pcu and enter the the level of service (LOS) with level B (5 – 15 sec/pcu). In traffic conditions in the next 10 years, the performance of the intersection will be very bad, it is known that the degrees of saturation for the north and south approaches are 0.94, 1.37 (ds > 0.75 ; saturated), while the East and West approaches produce degrees of saturation (ds > 0.75 ; saturation). ) respectively 0.19, 0.65 (ds < 0.75 ; unsaturated). The highest queue length is 1353.94 m, the average delay of the resulting intersection is 128.33 sec/pcu and the the level of service (LOS) is entered with the F level (>60 sec/pcu). while the East and West approaches produce degrees of saturation (ds) respectively 0.19, 0.65 (ds < 0.75 ; unsaturated). The highest queue length is 1353.94 m, the average delay of the resulting intersection is 128.33 sec/pcu and the the level of service (LOS) is entered with the F level (>60 sec/pcu). while the East and West approaches produce degrees of saturation (ds) respectively 0.19, 0.65 (ds < 0.75 ; unsaturated). The highest queue length is 1353.94 m, the average delay of the resulting intersection is 128.33 sec/pcu and the the level of service (LOS) is entered with the F level (>60 sec/pcu).

Dam break analysis using HEC-RAS and HEC-GeoRAS: A case study of Hidkal dam, Karnataka state, India

A dam is a structure constructed across river which stores water and supplies water for various purposes. Though the dams have many benefits, there is always a threat of dam break floods which are devastating in nature. Hence it becomes essential to analyze and simulate dam failure scenarios to understand the severity of dam break flood and identify areas under threat which helps in land use planning and developing emergency response plans. This study attempts to carry out dam break/breach analysis for the Hidkal dam using a one-dimensional hydraulic model called Hydraulic Engineering Center's River Analysis System (HEC-RAS). HEC-GeoRAS tool is used to extract river geometry data from the Cartosat-1 digital elevation model (DEM) and to generate the inundation map to identify the areas affected. The study involves the prediction of breach parameters, breach flood hydrograph, peak flow, flood arrival time, and generation of inundation maps. The dam break model is simulated for unsteady flow conditions using Probable Maximum Flood (PMF) corresponding to piping and overtopping failure scenarios. HEC-RAS tool is utilized to determine the breach outflow hydrograph and hydraulic conditions at critical downstream locations. Further, the breach outflow hydrographs are routed using dynamic flood wave routing. Further HEC-RAS model is simulated for breach parameters derived from five different empirical methods, and the results are compared. A sensitivity analysis is also carried out to know the variation of peak flow and maximum stage with respect to the breach parameters. The immediate downstream of the dam experience a peak flow of 72,085.45 m3/s and 78,454.82 m3/s and the corresponding inundation area of 75.224 km2 and 79.205 km2 due to piping failure and overtopping failure, respectively. Around twenty village located on the downstream of dam location gets affected due to flood produced by dam break. The analysis shows that overtopping failure is more severe than failure due to piping. The study shall further help authorities concerned to develop an emergency response plan and flood mitigation measures.

Detecting Rock Glacier Displacement in the Central Himalayas Using Multi-Temporal InSAR

Rock glaciers represent typical periglacial landscapes and are distributed widely in alpine mountain environments. Rock glacier activity represents a critical indicator of water reserves state, permafrost distribution, and landslide disaster susceptibility. The dynamics of rock glacier activity in alpine periglacial environments are poorly quantified, especially in the central Himalayas. Multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) has been shown to be a useful technique for rock glacier deformation detection. In this study, we developed a multi-baseline persistent scatterer (PS) and distributed scatterer (DS) combined MT-InSAR method to monitor the activity of rock glaciers in the central Himalayas. In periglacial landforms, the application of the PS interferometry (PSI) method is restricted by insufficient PS due to large temporal baseline intervals and temporal decorrelation, which hinder comprehensive measurements of rock glaciers. Thus, we first evaluated the rock glacier interferometric coherence of all possible interferometric combinations and determined a multi-baseline network based on rock glacier coherence; then, we constructed a Delaunay triangulation network (DTN) by exploiting both PS and DS points. To improve the robustness of deformation parameters estimation in the DTN, we combined the Nelder–Mead algorithm with the M-estimator method to estimate the deformation rate variation at the arcs of the DTN and introduced a ridge-estimator-based weighted least square (WLR) method for the inversion of the deformation rate from the deformation rate variation. We applied our method to Sentinel-1A ascending and descending geometry data (May 2018 to January 2019) and obtained measurements of rock glacier deformation for 4327 rock glaciers over the central Himalayas, at least more than 15% detecting with single geometry data. The line-of-sight (LOS) deformation of rock glaciers in the central Himalayas ranged from −150 mm to 150 mm. We classified the active deformation area (ADA) of all individual rock glaciers with the threshold determined by the standard deviation of the deformation map. The results show that 49% of the detected rock glaciers (monitoring rate greater than 30%) are highly active, with an ADA ratio greater than 10%. After projecting the LOS deformation to the steep slope direction and classifying the rock glacier activity following the IPA Action Group guideline, 12% of the identified rock glaciers were classified as active and 86% were classified as transitional. This research is the first multi-baseline, PS, and DS network-based MT-InSAR method applied to detecting large-scale rock glaciers activity.

Abstract 11305: Protective Effects of Homoarginine on Cardiovascular Function in a Mouse Model of Chronic Kidney Disease

Introduction: The level of homoarginine (hArg) in plasma correlates inversely with cardiovascular and renal disease. However, the cardioprotective mechanism of hArg in renal disease is currently unknown. In this study, we assessed hArg’s effects on cardiovascular function in mice with chronic kidney disease (CKD). Hypothesis: We have previously reported that hArg reduces fibrosis and helps preserve ejection fraction in a model of coronary artery disease. We now hypothesize that hArg supplementation will 1) decrease cardiac and renal fibrosis and inflammation in a model of CKD, 2) preserve cardiac geometry and function, 3) increase renal artery blood flow, and 4) increase survival. Methods: The mice used in this study had a mutation in the low density lipoprotein receptor on the C57BL/6 genetic background. Mice of both sexes (n=28) were fed a standard rodent diet supplemented with 0.1% (F) and 0.2% (M) adenine to induce CKD. Mice were randomly assigned to 14 μg/ml hArg (in drinking water) or placebo (PBO). Cardiac structure and function as well as renal blood flow were measured via high frequency ultrasound (Vevo 3100, VisualSonics). Results: LV geometry data of hArg treated male mice showed increased left ventricular (LV) mass (p<0.05) with normal LV internal diameter and increased LV wall thickness (p<0.01). In terms of cardiac function, ejection fraction (EF, p<0.05), fractional shortening (p<0.01), and cardiac output (p<0.01) were also increased in hArg treated male mice compared to placebo. No differences in renal blood flow were observed. Survival was not affected by hArg. Additionally, we observed decreased food consumption (p<0.01) and fecal output (p<0.001) in hArg treated mice with no difference in urine output compared with placebo. Conclusion: hArg treated male mice developed physiologic cardiac hypertrophy with preserved EF in the absence of LV dilation. Additionally, hArg affected the metabolic state of treated mice reflected in food consumption.

FaceVAE: Generation of a 3D Geometric Object Using Variational Autoencoders

Deep learning for 3D data has become a popular research theme in many fields. However, most of the research on 3D data is based on voxels, 2D images, and point clouds. At actual industrial sites, face-based geometry data are being used, but their direct application to industrial sites remains limited due to a lack of existing research. In this study, to overcome these limitations, we present a face-based variational autoencoder (FVAE) model that generates 3D geometry data using a variational autoencoder (VAE) model directly from face-based geometric data. Our model improves the existing node and edge-based adjacency matrix and optimizes it for geometric learning by using a face- and edge-based adjacency matrix according to the 3D geometry structure. In the experiment, we achieved the result of generating adjacency matrix information with 72% precision and 69% recall through end-to-end learning of Face-Based 3D Geometry. In addition, we presented various structurization methods for 3D unstructured geometry and compared their performance, and proved the method to effectively perform reconstruction of the learned structured data through experiments.

The recent stress state of Germany – results of a geomechanical–numerical 3D model

Abstract. A decisive criterion for the selection and the long-term safety of a deep geological repository for high radioactive waste is the crustal stress state and its future changes. The basis of any prognosis is the recent crustal stress state, but the state of knowledge in Germany is quite low in this respect. There are stress orientation data provided by the World Stress Map (WSM, Heidbach et al., 2018) and stress magnitude data from a database (Morawietz et al., 2020) for Germany, both providing selective information on the recent stress field. However, these data are often incomplete, of low quality and spatially unevenly distributed. Therefore, a 3D continuous description is not possible with these data so far, at most for the orientation of the maximum horizontal stress (SHmax), but not for the most important magnitudes of the minimum (Shmin) and SHmax. In the course of the SpannEnD project, a geomechanical–numerical 3D model of Germany is created, with which a continuous description of the complete tensor of the recent stress field in Germany is possible. The model covers an area of 1250×1000 km2 from Poland in the east, to France in the west, from Italy in the south to Scandinavia in the north. The depth extent is 100 km. Even though the focus is primarily on Germany, the model area was chosen to be so wide to minimize boundary effects and for a simplified definition of the displacement boundary conditions, which are ideally oriented perpendicular or parallel to the orientation of SHmax. The model contains a total of 21 units: The upper part of the lithospheric mantle, the lower crust, four laterally overlapping units of the upper crust, and 14 stratigraphic units of the sedimentary cover. The stratigraphic subdivision of the sedimentary cover is only done in the core area of the model; because this area is the focus of our study, our calibration data are mainly from this region and well-resolved geometry data are available. Outside of the core area, the sediments are grouped into an undifferentiated unit. The units are parameterized with density and elastic material parameters (Poisson's ratio and Young's modulus). The model has a lateral resolution of 2.5×2.5 km2 and a vertical resolution of a maximum of 240 m; in total it includes 11.1 million hexahedral elements. The equilibrium of forces between body and surface forces is solved by finite element method. The model is calibrated with Shmin and SHmax magnitudes from the WSM and data from the stress magnitude database. First, an initial stress state is generated and in a second step displacement boundary conditions are defined at the model edges, which are adjusted until a best-fit to the calibration data is found. The results show good agreement with both the SHmax orientation data from the WSM and the magnitudes of the two principal horizontal stresses (Shmin and SHmax) from the magnitude database.

Semi-automatic geometry modelling: faster and streamlined building simulation models

The architecture, engineering, and construction (AEC) industry experiences a growing need for building performance simulations (BPS) as facilitators in the design process. However, inconsistent modelling practice and varying quality of export/import functions entail error-prone interoperability with IFC and gbXML data formats. Consequently, repeated manual modelling is still necessary. This paper presents a coupling module enabling a semi-automated extract of geometry data from the BIM software Revit and a further translation to a BPS input file using Revit Application Programming Interface (API) and visual programming in Dynamo. The module is tested with three test cases which shows promising results for fast and structured semi-automatic geometry modelling designed to fit today’s practice.

An efficient physical-based method for predicting the long-term evolution of vertical railway track geometries

The dynamic wheel-rail contact forces resulting from the interaction between vehicle and track are responsible for the local track settlement. If these local settlements vary along the track, geometric irregularities develop further amplifying the dynamic loading of the track caused by the interaction between the vehicle and track. In this work, an efficient vehicle-track interaction (VTI) model is presented for predicting the long-term evolution of vertical track settlement during operation. The VTI model has two interacting components – vehicle and track. The vehicle model describes the vertical dynamics of an 8th of a car. The track model considers an elastic rail on discrete (sleeper) supports. Each sleeper location can have its own stiffness, relative height and settlement characteristics. Dependent on the distribution of stiffness and settlement behaviour along the track together with the initial track geometry, each sleeper settles dependent on the number of load cycles (vehicle passes). The track model is initialized with measured vertical track geometry data and static track deflection data at the beginning (day 0) for two types of track sections in the field, a track section where concrete sleepers with Under Sleeper Pads (USP) are used and a track section where only concrete sleepers are used. Using the same settlement model parameters (constant along the track) for the two tracks, the physical-based VTI model can predict the different track geometry quality evolution for both tracks over 350 days. Finally, the VTI model is used to assess the track geometry deterioration when the track/vehicle properties are changed. The prediction strength of the fast VTI model based on the physical understanding can assist in designing and optimizing tracks and in supporting of maintenance activities.

Significance of a software interoperability matrix for architectural engineering and construction industry

Traditional project management applications are appeared working separately of their participating project teams and isolating the input of each team to both geometry and non-geometry of the project. With the introduction of Building Information Modelling (BIM), Architectural, Engineering and Construction (AEC) industry expected it would be a panacea as a tool to effectively collaborate project teams and to efficiently share geometry and non-geometry data relevant to not only design and construction but also covering the whole life-cycle of the project. All these BIM functions are relied on its automation capability; in other words, BIM vision totally discourages manual processing of data. As a result, good interoperability practice needs to pass data automatically between applications of different project teams. Many international associations are working in search of full interoperability among BIM players of the project; however, the goal is yet to succeed. The current study identifies the impact due to poor interoperability between applications and takes considerable effort to minimise or eliminate if possible. Software Interoperability Matrix (SIM) is the proposed solution delivering the outcome. Action research is the methodology adopted to develop SIM, in which researchers and professionals actively participated. Major industry contribution of SIM is to realise interoperability issues between BIM players prior to the project and upon identification, precautionary measures can be taken introducing new plug-ins or completely switching to new compatible application if it is the only solution.

Modeling of the Molten Salt Reactor Experiment with SCALE

A SCALE model was developed for the Molten Salt Reactor Experiment (MSRE) benchmark that was recently added to the International Handbook of Evaluated Reactor Physics Benchmark Experiments. This SCALE model served as a basis for criticality calculations and nuclear data sensitivity and uncertainty analyses with the Monte Carlo code Shift and the TSUNAMI computational capabilities in the SCALE code system. The focus of this work is the assessment of the impact of nuclear data on the calculated eigenvalue results in support of the discussion of differences between the calculated and the experimental eigenvalue result. The differences in the eigenvalues obtained using the ENDF/B-VII.0, ENDF/B-VII.1, and ENDF/B-VIII.0 nuclear data libraries cover a relatively small range of 230 pcm. Since eigenvalue sensitivity of the MSRE is dominated by the neutron multiplicity and neutron capture of 235U and elastic scattering in graphite, relevant changes in the ENDF/B libraries for nuclear reactions (such as carbon capture) that caused large differences in other graphite-moderated systems did not have a significant impact. Propagation of nuclear data uncertainty results in an eigenvalue uncertainty of pcm with the major contributors being U neutron multiplicity, graphite elastic scattering, and 7Li neutron capture. All calculations resulted in large differences of 2000 pcm in eigenvalue compared to the benchmark experimental value. Several potential contributors to this difference—including uncertainties and gaps in the knowledge of the material, geometry, and nuclear data—were identified. Simplified models of the full MSRE core were developed, and similarity assessments were conduced with the full MSRE core model. It was found that simplified models can serve as adequate surrogates of the full-core model such that they can be used for performing selected nuclear data performance assessments with a lower computational burden.

Combining modern 3D reconstruction and thermal imaging: generation of large-scale 3D thermograms in real-time

ABSTRACT In recent years, due to the availability of affordable 3D sensors and the increased computing power, various methods for the generation of 3D thermograms have been developed. 3D thermal imaging describes the fusion of geometry and temperature data. A well-established approach is the fusion of data from depth and long-wave infrared (LWIR) cameras. However, these models generated in real-time have the limitation that the model size is limited due to inefficient data storage approach. Newer algorithms from Computer Vision promise to overcome this limitation by more efficient data handling and storage. Within this work, three state of the art 3D reconstruction algorithms from the computer vision community are compared and one of these is extended by overlaying thermal data, which allows the creation of large-scale 3D thermograms with a portable 3D measurement system. For this purpose, a geometric calibration is required, the data structure is adapted, and the handling of cyclic non-uniformity corrections required for uncooled LWIR cameras is described. The results will show exemplary 3D thermograms and the advantages compared to current existing systems.

The Impact of Ski Geometry Data and Standing Height on the Risk of Falling in Recreational Alpine Skiers

The aim of this study was to evaluate the impact of individual, equipment-related and environmental factors associated with falls among adult recreational skiers. Individual, equipment-related (ski geometry data) and environmental data were collected by questionnaire among uninjured skiers with and without reported falls during the skiing day. Ski length, side cut radius, and width of the waist were directly recorded from the ski and standing height was measured using a digital sliding caliper. Absolute ski length was relativized to body height. A total of 1174 recreational skiers participated in this study, of whom 13.5% (n = 158) reported at least one fall during the skiing day. Results of the multiple logistic regression analysis found that a lower age, a very good/good fitness level, a moderate skiing speed, a lower relativized ski length, and fresh and grippy snow conditions decreased, while a lower skill level, a larger sidecut radius and an easy slope difficulty increased risk of falling on ski slopes. Besides individual and environmental factors, a lower relativized ski length and a lower sidecut radius decreased the risk of falling. Considering these ski geometry parameters when buying new skis could potentially decrease the risk of falling and thus prevent injuries in recreational skiers.