scholarly journals Geometric Simplifications of Natural Caves in Ray-Tracing-Based Propagation Modelling

Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 2914
Author(s):  
Roman Novak ◽  
Andrej Hrovat ◽  
Michael D. Bedford ◽  
Tomaž Javornik
Keyword(s):  
Ray Tracing ◽  
Laser Scanning ◽  
3D Models ◽  
Computational Time ◽  
Modal Theory ◽  
Tracing Techniques ◽  
The Uk ◽  
Edge Collapse ◽  
Propagation Modelling ◽  
Vertex Clustering

Natural caves show some similarities to human-made tunnels, which have previously been the subject of radio-frequency propagation modelling using deterministic ray-tracing techniques. Since natural caves are non-uniform because of their inherent concavity and irregular limestone formations, detailed 3D models contain a large number of small facets, which can have a detrimental impact on the ray-tracing computational complexity as well as on the modelling accuracy. Here, we analyse the performance of ray tracing in repeatedly simplified 3D descriptions of two caves in the UK, i.e., Kingsdale Master Cave (KMC) Roof Tunnel and Skirwith Cave. The trade-off between the size of the reflection surface and the modelling accuracy is examined. Further, by reducing the number of facets, simulation time can be reduced significantly. Two simplification methods from computer graphics were applied: Vertex Clustering and Quadric Edge Collapse. We compare the ray-tracing results to the experimental measurements and to the channel modelling based on the modal theory. We show Edge Collapse to be better suited for the task than Vertex Clustering, with larger simplifications being possible before the passage becomes entirely blocked. The use of model simplification is predominantly justified by the computational time gains, with the acceptable simplified geometries roughly halving the execution time given the laser scanning resolution of 10 cm.

scholarly journals Internet Photogrammetry for Inspection of Seaports

2017 ◽  
Vol 24 (s1) ◽  
pp. 174-181 ◽  
Author(s):  
Zygmunt Paszotta ◽  
Malgorzata Szumilo ◽  
Jakub Szulwic
Keyword(s):  
Fundamental Matrix ◽  
Laser Scanning ◽  
3D Models ◽  
Digital Cameras ◽  
Correct Orientation ◽  
The Matrix ◽  
Transport Safety ◽  
Left And Right ◽  
Value Decomposition ◽  
The Relationship

Abstract This paper intends to point out the possibility of using Internet photogrammetry to construct 3D models from the images obtained by means of UAVs (Unmanned Aerial Vehicles). The solutions may be useful for the inspection of ports as to the content of cargo, transport safety or the assessment of the technical infrastructure of port and quays. The solution can be a complement to measurements made by using laser scanning and traditional surveying methods. In this paper the authors recommend a solution useful for creating 3D models from images acquired by the UAV using non-metric images from digital cameras. The developed algorithms, created and presented software allows to generate 3D models through the Internet in two modes: anaglyph and display in shutter systems. The problem of 3D image generation in photogrammetry is solved by using epipolar images. The appropriate method was presented by Kreiling in 1976. However, it applies to photogrammetric images for which the internal orientation is known. In the case of digital images obtained with non-metric cameras it is required to use another solution based on the fundamental matrix concept, introduced by Luong in 1992. In order to determine the matrix which defines the relationship between left and right digital image it is required to have at least eight homologous points. To determine the solution it is necessary to use the SVD (singular value decomposition). By using the fundamental matrix the epipolar lines are determined, which makes the correct orientation of images making stereo pairs, possible. The appropriate mathematical bases and illustrations are included in the publication.

The effect of N-acetylcysteine in a combined antibiofilm treatment against antibiotic-resistant Staphylococcus aureus

2020 ◽  
Vol 75 (7) ◽  
pp. 1787-1798
Author(s):  
Arthika Manoharan ◽  
Theerthankar Das ◽  
Gregory S Whiteley ◽  
Trevor Glasbey ◽  
Frederik H Kriel ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Dna Cleavage ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Combination Treatments ◽  
Resazurin Assay ◽  
Biofilm Architecture ◽  
Biofilm Disruption ◽  
The Uk

Abstract Background The WHO declared Staphylococcus aureus as a ‘pathogen of high importance’ in 2017. One-fifth of all bloodstream-related infections in Australia and 12 000 cases of bacteraemia in the UK (2017–18) were caused by the MRSA variant. To address the need for novel therapies, we investigated several permutations of an innovative combination therapy containing N-acetylcysteine (NAC), an antibiotic and an enzyme of choice in eradicating MRSA and MSSA biofilms. Methods Biofilm viability (resazurin assay) and colony count methods were used to investigate the effect of NAC, antibiotics and enzymes on S. aureus biofilm disruption and killing. The effects of NAC and enzymes on the polysaccharide content of biofilm matrices were analysed using the phenol/sulphuric acid method and the effect of NAC on DNA cleavage was determined using the Qubit fluorometer technique. Changes in biofilm architecture when subjected to NAC and enzymes were visualized using confocal laser scanning microscopy (CLSM). Results NAC alone displayed bacteriostatic effects when tested on planktonic bacterial growth. Combination treatments containing 30 mM NAC resulted in ≥90% disruption of biofilms across all MRSA and MSSA strains with a 2–3 log10 decrease in cfu/mL in treated biofilms. CLSM showed that NAC treatment drastically disrupted S. aureus biofilm architecture. There was also reduced polysaccharide production in MRSA biofilms in the presence of NAC. Conclusions Our results indicate that inclusion of NAC in a combination treatment is a promising strategy for S. aureus biofilm eradication. The intrinsic acidity of NAC was identified as key to maximum biofilm disruption and degradation of matrix components.

scholarly journals Modeling of Hypervelocity Impact Experiments Using Gamma-SPH Technique

2017 ◽  
Author(s):  
Jérôme Limido ◽  
Mohamed Trabia ◽  
Shawoon Roy ◽  
Brendan O’Toole ◽  
Richard Jennings ◽  
...  
Keyword(s):  
Computation Time ◽  
3D Models ◽  
Hypervelocity Impact ◽  
Side Impact ◽  
Particle Methods ◽  
Computational Time ◽  
Back Surface ◽  
Tensile Instability ◽  
Particle Hydrodynamics ◽  
And Performance

A series of experiments were performed to study plastic deformation of metallic plates under hypervelocity impact at the University of Nevada, Las Vegas (UNLV) Center for Materials and Structures using a two-stage light gas gun. In these experiments, cylindrical Lexan projectiles were fired at A36 steel target plates with velocities range of 4.5–6.0 km/s. Experiments were designed to produce a front side impact crater and a permanent bulging deformation on the back surface of the target without inducing complete perforation of the plates. Free surface velocities from the back surface of target plate were measured using the newly developed Multiplexed Photonic Doppler Velocimetry (MPDV) system. To simulate the experiments, a Lagrangian-based smooth particle hydrodynamics (SPH) is typically used to avoid the problems associated with mesh instability. Despite their intrinsic capability for simulation of violent impacts, particle methods have a few drawbacks that may considerably affect their accuracy and performance including, lack of interpolation completeness, tensile instability, and existence of spurious pressure. Moreover, computational time is also a strong limitation that often necessitates the use of reduced 2D axisymmetric models. To address these shortcomings, IMPETUS Afea Solver® implemented a newly developed SPH formulation that can solve the problems regarding spurious pressures and tensile instability. The algorithm takes full advantage of GPU Technology for parallelization of the computation and opens the door for running large 3D models (20,000,000 particles). The combination of accurate algorithms and drastically reduced computation time now makes it possible to run a high fidelity hypervelocity impact model.

scholarly journals EVALUATION OF MODEL RECOGNITION FOR GRAMMAR-BASED AUTOMATIC 3D BUILDING MODEL RECONSTRUCTION

2016 ◽  
Vol XLI-B4 ◽  
pp. 63-69
Author(s):  
Qian Yu ◽  
Petra Helmholz ◽  
David Belton
Keyword(s):  
Laser Scanning ◽  
Quality Evaluation ◽  
Evaluation Process ◽  
3D Models ◽  
Point Of View ◽  
Three Dimensions ◽  
Public And Private ◽  
Building Models ◽  
Evaluation Point ◽  
Increasing Demand

In recent years, 3D city models are in high demand by many public and private organisations, and the steadily growing capacity in both quality and quantity are increasing demand. The quality evaluation of these 3D models is a relevant issue both from the scientific and practical points of view. In this paper, we present a method for the quality evaluation of 3D building models which are reconstructed automatically from terrestrial laser scanning (TLS) data based on an attributed building grammar. The entire evaluation process has been performed in all the three dimensions in terms of completeness and correctness of the reconstruction. Six quality measures are introduced to apply on four datasets of reconstructed building models in order to describe the quality of the automatic reconstruction, and also are assessed on their validity from the evaluation point of view.

scholarly journals USE OF IMAGE BASED MODELLING FOR DOCUMENTATION OF INTRICATELY SHAPED OBJECTS

2016 ◽  
Vol XLI-B5 ◽  
pp. 327-334
Author(s):  
M. Marčiš ◽  
P. Barták ◽  
D. Valaška ◽  
M. Fraštia ◽  
O. Trhan
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Image Data ◽  
3D Models ◽  
Architectural Elements ◽  
Advantages And Disadvantages ◽  
Interior Spaces ◽  
Automated Processing ◽  
2D Drawing ◽  
Photogrammetric Measurement

In the documentation of cultural heritage, we can encounter three dimensional shapes and structures which are complicated to measure. Such objects are for example spiral staircases, timber roof trusses, historical furniture or folk costume where it is nearly impossible to effectively use the traditional surveying or the terrestrial laser scanning due to the shape of the object, its dimensions and the crowded environment. The actual methods of digital photogrammetry can be very helpful in such cases with the emphasis on the automated processing of the extensive image data. The created high resolution 3D models and 2D orthophotos are very important for the documentation of architectural elements and they can serve as an ideal base for the vectorization and 2D drawing documentation. This contribution wants to describe the various usage of image based modelling in specific interior spaces and specific objects. The advantages and disadvantages of the photogrammetric measurement of such objects in comparison to other surveying methods are reviewed.

scholarly journals Documentación 3D para la conservación del patrimonio histórico: el castillo de Priego de Córdoba

2021 ◽  
Vol 12 (24) ◽  
pp. 115
Author(s):  
Diego Francisco García-Molina ◽  
Ramón González-Merino ◽  
Jesús Rodero-Pérez ◽  
Bartolomé Carrasco-Hurtado
Keyword(s):  
Local Governments ◽  
Point Cloud ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Digital Preservation ◽  
3D Models ◽  
City Council ◽  
Heritage Management ◽  
Technological Advances ◽  
The 19Th Century

<p class="VARKeywords">One of the main objectives of heritage management policies is to promote measures aimed at the maintenance, restoration and enhancement of cultural and archaeological assets. To guarantee this, the responsible institutions must promote actions for the dissemination and transference of cultural heritage, as well as promoting actions with the greatest possible rigour, developing scientific and technical studies that support and improve intervention methods. Recent technological advances in fields such as photogrammetry, digital terrestrial scanning and 3D modelling have made a significant contribution to the digital preservation and dissemination of architectural heritage.</p><p class="VARKeywords">European administrations, in their desire of regional development, as well as the central or local governments have notably boosted the recovery of their rich and diverse heritage. A particular case is Priego de Cordoba’s Castle, a stronghold which was one of the most important monumental icons of the Andalusian period.</p><p class="VARKeywords">Currently, this site is the main target of many architectural interventions and a model due to the implementation of last generation techniques in digital preservation. The local archaeological department promotes a large number of interventions and archaeological excavations. This has made a priority to get a qualitative geometrical 3D documentation, and therefore a constantly updated the point cloud (xyzRGB).</p><p class="VARKeywords">This paper is focussed on presenting the results of the digital preservation process through 2D planimetry obtained from photogrammetric technics, 3D models, and geospatial data. These techniques are a previous step to large architectonical intervention planned in Priego de Cordoba’s Castle, in particular, the identified structures as Wall 1 and Tower 1.</p><p class="VARKeywords">Two out of the three studied structures can be found in Wall 1. They correspond to a cobblestone pavement located in the rampart of the Wall 1, which is a post-medieval period; a double-stepped semi-underground path, excavated in the infill of the wall. The third structure studied in this paper consists of a well, which drills vertically the infill of the wall of the Tower 1. This feature is interpreted in the last research as a vertical well to place the weights of the clock sited in this tower until the 19th century.</p><p class="VARKeywords">This work combines two techniques of geometric documentation to obtain a more complete point cloud. The terrestrial laser scanning, and the photogrammetry due to the higher colour performance, along with the completion of the point cloud obtained with the laser scanner. Along with this study, we will analyse the features which will better define the best technique to fit the documentation of the different structures. Their geometric characteristics, the incidence of sunlight or the accessibility will condition the use and choice of the technique.</p><p class="VARKeywords">We have stated that there is software nowadays which makes it easier to access and consult the information through new computing hardware. Besides, we have highlighted the importance of knowledge and synergy from the different stakeholders implied (city council, technological centre and private companies). The final goal consists of making the society aware of the capital importance of digital preservation as well as dissemination of science.</p>

scholarly journals EVALUATION OF MODEL RECOGNITION FOR GRAMMAR-BASED AUTOMATIC 3D BUILDING MODEL RECONSTRUCTION

2016 ◽  
Vol XLI-B4 ◽  
pp. 63-69 ◽  
Author(s):  
Qian Yu ◽  
Petra Helmholz ◽  
David Belton
Keyword(s):  
Laser Scanning ◽  
Quality Evaluation ◽  
Evaluation Process ◽  
3D Models ◽  
Point Of View ◽  
Three Dimensions ◽  
Public And Private ◽  
Building Models ◽  
Evaluation Point ◽  
Increasing Demand

In recent years, 3D city models are in high demand by many public and private organisations, and the steadily growing capacity in both quality and quantity are increasing demand. The quality evaluation of these 3D models is a relevant issue both from the scientific and practical points of view. In this paper, we present a method for the quality evaluation of 3D building models which are reconstructed automatically from terrestrial laser scanning (TLS) data based on an attributed building grammar. The entire evaluation process has been performed in all the three dimensions in terms of completeness and correctness of the reconstruction. Six quality measures are introduced to apply on four datasets of reconstructed building models in order to describe the quality of the automatic reconstruction, and also are assessed on their validity from the evaluation point of view.

scholarly journals ANALYSIS OF 3D BUILDING MODELS ACCURACY BASED ON THE AIRBORNE LASER SCANNING POINT CLOUDS

2018 ◽  
Vol XLII-2 ◽  
pp. 797-804 ◽  
Author(s):  
W. Ostrowski ◽  
M. Pilarska ◽  
J. Charyton ◽  
K. Bakuła
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Large Scale ◽  
Point Clouds ◽  
3D Models ◽  
Airborne Laser Scanning ◽  
Aerial Images ◽  
Statistical Parameters ◽  
Airborne Laser ◽  
Building Models

Creating 3D building models in large scale is becoming more popular and finds many applications. Nowadays, a wide term “3D building models” can be applied to several types of products: well-known CityGML solid models (available on few Levels of Detail), which are mainly generated from Airborne Laser Scanning (ALS) data, as well as 3D mesh models that can be created from both nadir and oblique aerial images. City authorities and national mapping agencies are interested in obtaining the 3D building models. Apart from the completeness of the models, the accuracy aspect is also important. Final accuracy of a building model depends on various factors (accuracy of the source data, complexity of the roof shapes, etc.). In this paper the methodology of inspection of dataset containing 3D models is presented. The proposed approach check all building in dataset with comparison to ALS point clouds testing both: accuracy and level of details. Using analysis of statistical parameters for normal heights for reference point cloud and tested planes and segmentation of point cloud provides the tool that can indicate which building and which roof plane in do not fulfill requirement of model accuracy and detail correctness. Proposed method was tested on two datasets: solid and mesh model.

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