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1

A novel method for fast generation of 3D objects from multiple depth sensors

Szmuc Tomasz, Mrówka Rafał, Brańka Marek, Ficoń Jakub, Pięta Piotr

Journal of Artificial Intelligence and Soft Computing Research

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2023

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Vol. 13, No. 2

95--105

EN

Scanning real 3D objects face many technical challenges. Stationary solutions allow for accurate scanning. However, they usually require special and expensive equipment. Competitive mobile solutions (handheld scanners, LiDARs on vehicles, etc.) do not allow for an accurate and fast mapping of the surface of the scanned object. The article proposes an end-to-end automated solution that enables the use of widely available mobile and stationary scanners. The related system generates a full 3D model of the object based on multiple depth sensors. For this purpose, the scanned object is marked with markers. Markers type and positions are automatically detected and mapped to a template mesh. The reference template is automatically selected for the scanned object, which is then transformed according to the data from the scanners with non-rigid transformation. The solution allows for the fast scanning of complex and varied size objects, constituting a set of training data for segmentation and classification systems of 3D scenes. The main advantage of the proposed solution is its efficiency, which enables real-time scanning and the ability to generate a mesh with a regular structure. It is critical for training data for machine learning algorithms. The source code is available at https://github.com/SATOffice/improved_scanner3D.

2

New method to analyze resolution acquisition for intraoral scanners

Desoutter Alban, Subsol Gérard, Fargier Eric, Sorgius Alexandre, Tassery Hervé, Fages Michel, Cuisinier Frédéric

Metrology and Measurement Systems

|

2022

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Vol. 29, nr 2

391--404

EN

In dentistry, 3D intraoral scanners (IOSs) are gaining increasing popularity in the production of dental prostheses. However, the quality of an IOS in terms of resolution remains the determining factor of choice for the practitioner; a high resolution is a quality parameter that can reduce error in the production chain. To the best of our knowledge, the evaluation of IOS resolution is not clearly established in the literature. This study provides a simple assessment of resolution of an IOS by measuring a reference sample and highlights various factors that may influence the resolution. A ceramic tip was prepared to create a very thin object with an edge smaller than the current resolution stated by the company. The sample was scanned with microCT (micro-computed tomography) and an IOS. The resulting meshes were compared. In the mesh obtained with the IOS, the distance between two planes on the edge was approximately 100 micrometers, and that obtained with microtomography was 25 micrometers. The curvature values were 27.46 (standard deviation - SD) 14.71) μm-1 and 5.18 (SD 1.16) μm-1 for microCT and IOS, respectively. These results show a clear loss of information for objects that are smaller than 100 μm. As there is no normalized procedure to evaluate resolution of IOSs, the method that we have developed can provide a positive parameter for control of IOSs performance by practitioners.

3

Detection of periodic displacements of shell structures with edges using spline surfaces, meshes and point clouds

Lenda Grzegorz, Abrachamowicz Katarzyna

Reports on Geodesy and Geoinformatics

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2021

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Vol. 112

27--33

EN

This research paper tackles the problem of determining displacements of complex-shaped shell structures, measured periodically using laser scanning. Point clouds obtained during different measurement epochs can be compared with each other directly or they can be converted into continuous models in the form of a triangle mesh or smooth patches (spline functions). The accuracy of the direct comparison of point clouds depends on the scanning density, while the accuracy of comparing the point cloud to the model depends on approximation errors that are formed during its creation. Modelling using triangle meshes flattens the local structure of the object compared to the spline model. However, if the shell has edges in its structure, their exact representation by spline models is impossible due to the undulations of functions along them. Edges can also be distorted by the mesh model by their chamfering with transverse triangles. These types of surface modelling errors can lead to the generation of pseudo-deformation of the structure, which is difficult to distinguish from real deformation. In order to assess the possibility of correct determination of deformation using the above-mentioned methods, laser scanning of a complex shell structure in two epochs was performed. Then, modelling and comparison of the results of periodic measurements were carried out. As a result of the research, advantages and disadvantages of each method were identified. It was noticed that none of the methods made it possible to correctly represent all deformations while suppressing pseudo-deformation. However, the combination of their best qualities made it possible to determine the actual deformation of the structure.

4

Resolution in the 3D modeling of objects for additive manufacturing and reverse engineering – shutter effect

Coutiño-Moreno Elvis, Estrada Quirino, Maldonado-Onofre Daniel, Rodriguez-Mendez Alejandro, Gomez-Giron Julio

Applied Computer Science

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2021

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Vol. 17, no 1

40--52

EN

This article presents a proportional relationship between Shutter and the value of the resolution scanning system that allows decision making for modeling 3D parts used in reverse engineering and additive manufacturing. As a first step, the object of interest is treated to dim excessive brightness, then the object is scanned (by point cloud or mesh) with the use of a Handyscan 700 scanner. The point cloud is processed with the Geomagic software Desing X to generate a CAD image and a “.stl” file for 3D printing.

5

Deflection ductility of slabs made of hybrid mesh-and-fibre-reinforced cement-based composite

Sakthivel P. B.

Archives of Civil Engineering

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2017

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Vol. 63, nr 3

115--137

EN

Steel Mesh-Reinforced Cementitious Composites (SMRCC) (traditionally known as ferrocement) have been in existence for few decades, but have some limitations set on element thickness and number of reinforcing mesh layers and the resulting deflection ductility. Therefore, the author has made an attempt to explore whether deflection ductility will improve in mesh-reinforced cementitious composites (25 mm thick) if discontinuous fibres are added to slab elements. For this purpose, thin slab elements of dimensions 700 mm (length) × 200 mm (width) × 25 mm (thickness) were cast and subjected to four point bending tests. Based on the flexural tests conducted on SMRCC (Control Slab Elements, cast with Steel Mesh Volume of reinforcement, MVr=0.78, 0.94, and 1.23%) and Hybrid Mesh-and-Fibre-Reinforced Cement Based Composite (HMFRCBC) (Test Slab Elements, combining MVr=0.78, 0.94 and 1.23% and Polyolefin Fibre Volume fraction, PO-FVf=0.5-2.5% of volume of specimens, with 0.5% interval), load-deflection and the deflection ductility index were analyzed. From the flexural load-deflection curves it has been observed that HMFRCBC slabs demonstrate higher flexural load-carrying capacity and deflection ductility when compared to SMRCC slabs. This study shows that higher the polyolefin fibre volume fraction (PO-FVf) from 0.5 to 2.5% (with a 0.5% interval) in HMFRCBC slabs, the higher the flexural deflection ductility. The Deflection Ductility Index (DDI) of HMFRCBC (with 5 layers of mesh and PO-FVf=2.5%) is 4.5 times that of SMRCC. This study recommends that HMFRCBC can be used as an innovative construction material due to its higher flexural ductility characteristics.

PL

Cementowe materiały kompozytowe zbrojone siatką stalową (tradycyjnie znane jako siatkobeton) stanowią innowacyjny materiał składający się z hydraulicznej zaprawy cementowej oraz ciasno rozmieszczonych warstw ciągłej siatki stalowej o małej średnicy oczek do stworzenia sztywnej konstrukcji, a ze względu na swoją doskonałą wytrzymałość na zginanie są wykorzystywane jako prefabrykaty dachowe. Pomimo, że na przestrzeni ostatnich kilkudziesięciu lat na świecie wybudowano kilka konstrukcji siatkobetonowych (prefabrykowane i wylewane na miejscu pierwszorzędne oraz drugorzędne konstrukcje dachowe i elementy belkowe, panele ścienne, ściany zatrzymujące ziemię, prefabrykowane schody, ławki, sklepienia, kopuły, cienkie pergole oraz systemy ochrony przeciwsłonecznej, ściany graniczące z morzem, nadziemne zbiorniki wodne, podziemne zbiorniki ściekowe, baseny i łodzie – wymieniając jedynie kilka), istnieją pewne ograniczenia dotyczące grubości elementu, a także liczby warstw siatki zbrojeniowej oraz wynikowego odchylenia plastyczności. Plastyczność jest niezwykłym zjawiskiem umożliwiającym odkształcenie elementu przy lub w okolicach granicznego obciążenia niszczącego bez znacznej utraty jego wytrzymałości. O zachowaniu plastycznym świadczy jego zdolność do utrzymania wyższych poziomów obciążenia po pierwszym pękaniu na skutek dużych odkształceń. Poprzednie badania wskazują, że nieciągłe włókna mogą być dodane do matrycy cementowej cementowych materiałów kompozytowych zbrojonych siatką stalową w formie hybrydowej w celu poprawy jej wytrzymałości na zginanie oraz odchylenia plastyczności.

6

Importance of economic and noneconomic factors in collaborative consumption

Chudzian J.

Ekonomia i Zarządzanie

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2015

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Vol. 7, no. 4

14--22

EN

The main goal of this paper is to point out the awareness and activity of young consumers in the area of collaborative activities and to indicate what factors condition such attitudes and behaviours. The study performed has comparative character and was conducted on the group of active user of one of the forms of collaborative consumption and on the control group with a use of questionnaire. Results show clearly that people who do not use this form of collaborative consumption consider economical aspects more important. Active users, on the other hand, value higher ecological, social and psychological benefits. Additionally, the research shows the profile of collaborative consumption users as well as factors that drive their activity. This research aims at answering hypotheses spread about collaborative consumption being a trend corresponding only to economic crisis.

7

Analysis of mesh settings during FEM modelling of abrasive water jet flow

Wstawska I., Ślimak K.

Archives of Mechanical Technology and Automation

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2014

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Vol. 34, no. 2

41--50

EN

The paper presents issues related to the flow modelling during abrasive water jet machining. A few of cutting head model assumptions were tested and their influence on the velocity of the stream was assessed. Mainly, modelling of abrasive water jet flow through the canals of the water jet cutting head, mesh parameters selection and necessary simplifications are discussed. This allowed to form recommendations for mesh setup and for the further research. Also, the achieved results are presented in the form of exemplary model built upon above mentioned recommendations.

PL

W artykule rozpatrywano zagadnienia związane z modelowaniem przepływu strugi w trakcie obróbki wodno-ściernej. Analizowano różne założenia do modelu głowicy tnącej oraz ich wpływ na uzyskiwaną prędkość strugi. Omówiono głównie przepływ strumienia wodno-ściernego przez kanały głowicy tnącej, dobór parametrów siatki oraz konieczne uproszczenia. Takie podejść umożliwiło określenie zaleceń dotyczących doboru parametrów siatki oraz pozwoliło na wskazanie kierunków przyszłych prac. Przedstawiono także uzyskane wyniki w postaci przykładowego modelu przepływu utworzonego z uwzględnieniem wspomnianych zaleceń.

8

Stimulation of unconventional hydrocarbon reservoirs

Szabo D., Pinka J., Stolićny E.

AGH Drilling, Oil, Gas

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2014

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Vol. 31, no. 2

307--313

EN

In the "new age" oil and gas industry came more and more into focus term of unconventional hydrocarbons. Gained experience and success in the United States tight gas sand reservoirs Piceance, Anadarko, Greater Green, Lobo fields confirmed the hidden potential of unconventional hydrocarbon resources. In some production and development areas called coal bed seam, shale gas and tight sand reservoirs without intensifying operations isn't possible to produce commercial gas volumes. Used practises and gained large experiences in the crude oil fields are commonly used in the shale and tight gas fields across the United States. Application of these technologies of stimulation methods like fracturing in Europe is at the very beginning. Pioneer investors are waiting in all Europe for the well testing results from the first dozen fractured shale gas and tight sand reservoirs. Test results could have significant influence on the future planned massive drilling campaign of exploration of the unconventional hydrocarbon resources

9

Performance evaluation of Tree and Mesh ZigBee Network Topologies used in Street Lighting Control Systems

Lavric A., Popa V., Finis I., Males C.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 4

168-171

EN

The design of a high performance street lighting control system is an important issue. This paper focuses on an assessment of the performance of the ZigBee mesh and tree network topologies which, can be implemented in different street lighting control network configurations. The paper also presents the performance evaluation of three configurations in order to select the best candidate that can be integrated within a street lighting control system. The data reveal that the tree topology is much more efficient than the mesh topology. Also, the impact of the acknowledgment (ACK) communication mechanism on the network throughput and on the end-to-end delay application parameter is analyzed.

PL

W artykule przedstawiono wyniki analizy działania sieci w topologii siatki ZigBee oraz drzewa, w zastosowaniu do sterowania oświetleniem ulicznym. Ocenie poddane skuteczność doboru najlepszych kandydatów do integracji z systemem oświetlenia w odniesieniu do trzech konfiguracji. Stwierdzono znacznie większą skuteczność działania struktury drzewiastej w stosunku do struktury siatki.

10

Interworking and cross-layer service discovery extensions for IEEE 802.11s wireless mesh standard

Gierłowski K.

Journal of Telecommunications and Information Technology

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2013

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nr 3

97--105

EN

With the rapid popularization of mobile end-user electronic devices, wireless network technologies begin to play a crucial role as networks access technologies. While classic point-to-multipoint wireless access systems, based on fixed infrastructure of base stations providing access to clients, remain the main most popular solution, an increasing attention is devoted to wireless mesh systems, where each connecting client can extend overall resources of the network by becoming a network node capable of forwarding transit traffic. This ability results in severe reduction of the necessary network infrastructure, provides through coverage (thereby offering significant step towards ubiquity of network access) and offers massive redundancy. One of the most promising wireless mesh solutions currently being developed is an IEEE 802.11s standard, based on popular Wi-Fi technology. It combines low deployment costs with comprehensive suite of mechanisms able to operate a self-forming, autoconfigurable, dynamically extending, and secure mesh solution. However, despite its advantages, the standard lacks sufficient support for a number of functionalities, which can lead to significant inefficiency and degradation of service quality in real-world IEEE 802.11s network deployments. In the paper we propose a number of extensions of IEEE 802.11s mechanisms, designed to provide better service quality in case of real-world deployment scenarios, especially in case of large systems. Both propositions introduce modifications to mesh path discovery and interworking procedures, while retaining compatibility with standard solution. Their basic functionality and efficiency have been verified by means of simulation model in large-scale, self-organizing mesh structure. Subsequently they have been implemented and tested in real-world, access network testbed deployment. The results clearly indicate their utility, particularly in case of larger deployments of this network system type.

11

Motion simulation of industrial screen meshes

Modrzewski R., Wodziński P.

AGH Journal of Mining and Geoengineering

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2012

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Vol. 36, no. 4

91-100

EN

This paper is an account of a method of motion simulation of vibrating screen meshes developed and tested at the Department of Process Equipment at the Technical University of Łódź. It is obvious that a type of screen vibration and its parameters such as throwing index have a crucial influence on the efficacy of separating granular mixtures. The possibility of simulating this motion before construction of a machine helps to save both the time and money, and it is also a significant contribution to further kinematic tests because it gives the chance of verifying the proper functioning of electronic meter circuits.

PL

Niniejsza praca prezentuje opis metody symulacji ruchu sit w przesiewaczach swobodnie drgających opracowanych i badanych w Katedrze Aparatury Procesowej Politechniki Łódzkiej. Jak wiadomo, rodzaj ruchu drgającego przesiewaczy, oraz parametry tego ruchu, takie jak np. wskaźnik podrzutu, mają decydujący wpływ na skuteczność procesu rozdzielania mieszanin ziarnistych. Możliwość symulacji tego ruchu jeszcze przed zbudowaniem konkretnej maszyny pozwala zaoszczędzić zarówno czas jak i pieniądze, jest też istotnym wsparciem późniejszych badań kinematycznych, gdyż pozwala zweryfikować poprawność działania elektronicznych układów pomiarowych.

12

Optimization of a nonconventional engine evaporator

Kovalčik A., Toporcer E.

Journal of KONES

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2010

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Vol. 17, No. 2

217-223

EN

The papers deal with the optimization of the evaporator of a nonconventional combustion engine. Lithium bromide liquid (LiBr - an alternative cooling medium) flows in a cooling circuit of a nonconventional energetic unit. The solved energetic system is defined in the area of trigeneration systems. The mentioned system is a source of electric energy, cold and heat too. The space geometrical model corresponding to the geometry of the original evaporator is created in the CAD (Computer Aided Design) software CATIA. Only one half of the evaporator is created because of the decrease in the demand on the computational means. This CAD model is then imported into the preprocessor Gambit. The imported model is repaired and a suitable mesh is then created. The last step is the definition of the types of boundary conditions. The completed computational mesh is then exported from Gambit and imported into the CFD (Computational Fluid Dynamics) software Fluent. Fluent is used for the numerical simulation of the cooling medium flow in an evaporator. The simulation shows the filling of the evaporator cone, the time when the cooling medium starts to pour through the edge of the evaporator cone, the filling of the evaporator ring and finally also the fact that the off-take is able to take away the needed amount of cooling liquid from the evaporator.

13

Algorithms for reliable networks deployment in mesh topology with flow control

Debita G., Staniec K.

International Journal of Electronics and Telecommunications

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2010

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Vol. 56, No. 1

73-79

EN

The article presents innovative methods for designing and controlling topology in mesh networks. The authors of the paper simulate the procedure of deploying a mesh structure and prove that the shortest path for such a network is also one with the least number of hops in the sense of intermediate nodes.

14

Analiza szerokopasmowych sieci bezprzewodowych serii IEEE 802.11 i 16 (WiFi i WiMAX) z transmisją wieloetapową

Gierłowski K., Woźniak J.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2008

|

R. 81, nr 8-9

925-936

PL

Dokonano analizy różnych, odmiennych technologicznie rozwiązań sieci złożonych typu mesh, tj. z transmisją wieloetapową, opartych na standardowych modułach serii IEEE 802.11 i 16 (WiFi i WiMAX). Wskazano specyficzne właściwości takich sieci, jak też zwrócono uwagę na ich potencjalną przydatność i nowe obszary zastosowań, a także pokazano korzyści oferowane przez rozwiązania rozproszone. Wskazano też problemy wynikające z potrzeby bądź konieczności współpracy różnych technik.

EN

The paper discusses promising proposals of wireless broadband mesh networks constructed with the use of standard IEEE 802.11 and 16 modules, and analyses of scenarios of operation and possible applications of such solutions. The goal of the article is also to point out specific features and new environments for mesh installations, together with showing advantages and benefits brought by such networks. Some remarks on coexistence and cooperation aspects of different technologies are also given.

15

Optimized point cloud triangulation for 3D scanning systems

Sitnik R., Karaszewski M.

Machine Graphics and Vision

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2008

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Vol. 17, No. 4

349-371

EN

This article deals with a new Mesh3D algorithm used for triangulation of point clouds obtained from real 3D objects via optical scanning systems. The algorithm is characterized by a high level of automation. Triangle meshes obtained by using this algorithm are of a better quality than those created through the application of popular algorithms. Procedures used for areas with large shape gradients allow us to obtain a higher accuracy of a geometric object representation. It is also a very efficient method even when the procedure of point clouds smoothing is applied initially. The implementation of this kind of a complex mesh quality assessment system enables us to improve the smoothness and continuity of the mesh, which allows us to obtain more realistic and visually better reconstructions of objects.

16

A hybrid-mesh solution for coverage issues in WiMAX metropolitan area networks

Gierłowski K., Wodniak J., Nowicki K.

Journal of Telecommunications and Information Technology

|

2008

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nr 1

20-28

EN

The new WiMAX technology offers several advantages over the currently available (GSMor UMTS-based) solutions. It is a cost effective, evolving, and robust technology providing quality of service guarantees, high reliability, wide cov- erage and non-line-of-sight (NLOS) transmission capabilities. All these features make it particularly suitable for densely populated urban environments. In this paper we discuss the design and implementation difficulties concerning network coverage discovered in a test-bed implementation of WiMAX. We point out the presence of unexpected "white spots" in the coverage, which are not inherently characteristic of the WiMAX concept. As a possible remedy to this significant drawback of the otherwise very promising technology, we consider reconfigurable mesh organization of WiMAX base stations. We also suggest directions for further development of this kind of network operation, partly based on our practical experience. Despite the clear advantages of the mesh mode in WiMAX networks, its development is currently at an early stage, due to the high complexity of the necessary mechanisms. In this situation, we propose an original, much simpler solution: the so-called support-mesh mode.

17

Mesh representation of simply connected 3D objects in visualisation of melting phenomena

Szajerman D.

Machine Graphics and Vision

|

2006

|

Vol. 15, No. 3/4

621-630

EN

This paper discusses some aspects of the physics approach to simulation of the melting phenomena: energy distribution in a volumetric model, substance vaporization and their relation to geometric properties of a model. A new simulation method for melting objects is presented. The method consists in mesh deformations which allow simulation of melting phenomena with preservation of visual effects similar to those achieved in the volumetric approach. Moreover, a few examples of melted models are included to show visual effects achievable with the help of the method. Meshes used with the method should be simply connected sets. This means there are no holes in them, and that they constitute a single object through the whole simulation process. Furthermore, a new method for determining whether a point is situated inside a given polygon is shown.

18

Obciążalność zazębienia przekładni ślimakowych

Marciniak T.

Zeszyty Naukowe. Rozprawy Naukowe / Politechnika Łódzka

|

2004

|

Z. 329

3-94

PL

Przedstawiona praca dotyczy zagadnienia obliczania obciążalności zazębienia przekładni ślimakowych. Prezentowana metoda, w odróżnieniu od dotychczas stosowanych metod, daje zadowalającą zgodność z wynikami badań. Rezultaty takie zapewniło zastosowanie w obliczeniach zmodyfikowanych wzorów Hertza i uwzględnienie w rozkładzie nacisków zmiennej sztywności zazębienia. Ze względu na złożoność geometrii kontaktu stykających się powierzchni opracowano algorytmy i oprogramowanie pod nazwami TESTER i MOMENT, które stanowią narzędzie do wykonania obliczeń. Przedstawione w tej pracy podstawy teoretyczne obliczania obciążalności zostały potwierdzone prezentowanymi w pracy badaniami eksperymentalnymi przekładni. Na tej podstawie opracowano metodę badań modelowych zużycia przekładni ślimakowych pozwalającą z bardzo dobrym przybliżeniem odtworzyć warunki pracy w zazębieniu. Zbudowano stanowisko i przeprowadzono badania. Uzyskane wyniki obliczeń i przeprowadzonych badań pozwoliły na opracowanie podstaw racjonalnego doboru parametrów geometrycznych zazębienia przyjmując jako kryterium obciążalność zazębienia.

EN

The thesis concerns on calculations of the load capacity of meshing in worm transmission. The method presented gives a satisfactory conformity with experimental results. Such results were obtained due to application of modified Hertz equations and taking variable teeth stiffness into consideration in calculations. Due to a very complex geometry of teeth contact in worm transmission the appropriate algorithms and computer programs, TESTER and MOMENT, were developed to carry out calculations. Theoretical basics of calculations of load capacity of meshing in worm gear transmission presented in the thesis were confirmed by experiments. On this basis, the method of model investigations of worm gear transmission wear was proposed which makes it possible, with a very good approximation, to simulate working conditions in teeth meshing. The experimental stand was designed and produced to carry out researches in this field to proof the model. Computed and experimental results obtained made it possible to elaborate basics for rational selection of teeth mesh geometrical parameters taking load capacity as a basic criterion.

19

Wpływ kąta zarysu narzędzia na parametry wieńca zębnika typu BBW

Kozik B.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

|

2004

|

z. 64 [217]

100--103

PL

W artykule przedstawiono wpływ kąta zarysy narzedzia na podstawowe parametry wieńca zębatego zębnika przekładni walcowej z zazębieniem wypukło-wklęsłym typu BBW.

EN

The article presents the influence of pressure angle of the tool on basic parameters of teeth of pinion in the concavo-convex BBW type gearing.

20

Construction of differential quotients using the control volume method

Lara S., Pawlak E.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2004

|

z. 78

221-224

EN

In the paper the control volume method is applied for the construction of differential quotients approximating the operator (delta2 T) being a typical component appearing in the well known diffusion equation (2D problem is discussed). It turned out that for non-typical differential meshes it is possible to find the form of (delta2 T) approximation using the equations resulting from the control volume method (CVM) [1]. The results obtained in this scope will be below presented.