Wyniki wyszukiwania - BazTech

1

Reverse engineering-inspired parametric 3D geometry model of marine propeller

Zheng Long, Chen Shunhuai, Chen Xinyu, Ji Shengchen

Polish Maritime Research

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2023

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nr 3

35--47

EN

In this study, an effective parametric 3D geometry model of a propeller was established with the aid of reverse engineering. The goal is to reduce the free parameters while automating the modelling of the propeller. The process of building the parametric model begins by generating an initial point cloud by defining the feature matrix associated with the propeller blade profile shape. Subsequently, the initial point cloud is deformed and refined by the deformation feature matrix and resampling. Finally, a 3D geometry model of the propeller is generated by surface reconstruction. The model can be built automatically by interactively modifying the feature matrices. Two numerical analyses illustrate the performance of the parametric 3D geometry model. Specifically, two propellers are constructed using the proposed model to estimate the shape error between the reconstructed propellers and the original offset of the propellers. These propellers are selected as research objects to determine the hydrodynamic performance error between the propeller constructed by the proposed model and a benchmark propeller. According to the results of the numerical study, the parametric 3D geometry model can precisely reconstruct the aforementioned geometry within a valid error range. The hydrodynamic error analysis demonstrates that the geometric inaccuracy from the reconstructed model has less impact on the propeller performance. This indicates that the model described in this study is generalised and robust. Moreover, some uncommon propeller CAD models were generated in batches using the parametric 3D geometry model.

2

Badanie dokładności rekonstrukcji powierzchni z interferogramu światła białego z wykorzystaniem metod bazujących na transformacie Hilberta

Wrzuszczak M., Khoma A.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 4

210--215

PL

W pracy opisano metody rekonstrukcji profilu powierzchni z interferogramu światła białego. Po krótkim wprowadzeniu do teorii sygnałów analitycznych, zaproponowano cztery metody rekonstrukcji profilu powierzchni wykorzystujące dyskretną transformatę Hilberta. Przedstawiono wyniki badań dokładności tych metod na przykładzie rekonstrukcji powierzchni płaskiej pochyłej oraz kulistej.

EN

The paper describes methods of surface profile reconstruction from the white light interferogram. The theoretical basis for a theory of analytical signals are given. Four methods for the reconstruction of the surface profile using a discrete Hilbert transform are offered. The accuracy analyses of these methods are presented on an example of the slant planar surface and spherical surface reconstruction.

3

Surface Topology Reconstruction From The White Light Interferogram By Means Of Prony Analysis

Khoma A., Zygarlicki J.

Metrology and Measurement Systems

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2015

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Vol. 22, nr 4

479--490

EN

The paper presents a new method of surface topology reconstruction from a white light interferogram. The method is based on interferogram modelling by complex exponents (Prony method). The compatibility of white light interferogram and Prony models has already been proven. Effectiveness of the method was tested by modelling and examining reconstruction of tilted and spherical surfaces, and by estimating the reconstruction accuracy.

4

Accuracy assessment for cad modeling of freeform surface described by equation

Golba G.

Acta Mechanica et Automatica

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2015

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Vol. 9, no. 2

110--114

EN

This paper presents the results of comparative analysis of modeling accuracy the freeform surface constructed by using a variety of algorithms for surface modeling. Also determined the accuracy of mapping the theoretical freeform surface described by mathematical equation. To model surface objects used: SolidWorks 2012, CATIA v5 and Geomagic Studio 12. During the design process of CAD models were used: profile curves, fitting parametric surface and polygonal mesh. To assess the accuracy of the CAD models used Geomagic Qualify 12. On the basis of analyse defined the scope of application of each modeling techniques depending on the nature of the constructed object.

5

An algorithm of semi-Delaunay triangulation of points cloud scattered on a surface

Kucwaj J.

Computer Science

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2014

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Vol. 15 (3)

329--348

EN

The purpose of this paper is to generalize the Delaunay[13] triangulation onto surfaces. A formal definition and an appropriate algorithm are presented. Starting from a plane domain Delaunay triangulation definition, a theoretical approach is evolved (which is a background for further considerations). It has been proven that, in the case of a plane surface, the introduced Delaunay triangulation of surfaces is identical to classical Delaunay triangulation of the plane domain. The proposed algorithm is implemented and numerical results are shown.

6

Automatyczna rekonstrukcja modeli 3D małych obiektów bliskiego zasięgu

Zawieska D.

Archiwum Fotogrametrii, Kartografii i Teledetekcji

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2013

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Vol. 25

295--302

EN

Reconstruction of three-dimensional, realistic models of objects from digital images has been the topic of research in many areas of science for many years. This development is stimulated by new technologies and tools, which appeared recently, such as digital photography, laser scanners, increase in the equipment efficiency and Internet. The objective of this paper is to present results of automatic modeling of selected close range objects, with the use of digital photographs acquired by the Hasselblad H4D50 camera. The author's software tool was utilized for calculations; it performs successive stages of the 3D model creation. The modeling process was presented as the complete process which starts from acquisition of images and which is completed by creation of a photorealistic 3D model in the same software environment. Experiments were performed for selected close range objects, with appropriately arranged image geometry, creating a ring around the measured object. The Area Base Matching (CC/LSM) method, the RANSAC algorithm, with the use of tensor calculus, were utilized form automatic matching of points detected with the SUSAN algorithm. Reconstruction of the surface of model generation is one of the important stages of 3D modeling. Reconstruction of precise surfaces, performed on the basis of a non-organized cloud of points, acquired from automatic processing of digital images, is a difficult task, which has not been finally solved. Creation of poly-angular models, which may meet high requirements concerning modeling and visualization is required in many applications. The polynomial method is usually the best way to precise representation of measurement results, and, at the same time, to achieving the optimum description of the surface. Three algorithm were tested: the volumetric method (VCG), the Poisson method and the Ball pivoting method. Those methods are mostly applied to modeling of uniform grids of points. Results of experiments proved that incorrect utilization of these methods results in various artifacts and deformations of models. After generation of a triangular grid of the modeled surface, results were visualized using the shading methods and texturing of the cloud of points. The accuracy of obtained reconstructions of the model surface equaled bellow 1 mm.

PL

Celem niniejszego artykułu jest prezentacja wyników automatycznego modelowania wybranych obiektów bliskiego zasięgu (głowa manekina, kamień) z wykorzystaniem obrazów cyfrowych z aparatu Hasselblad H4D50. Do obliczeń wykorzystano autorski program, realizujący kolejne etapy tworzenia modelu 3D. Proces modelowania został zaprezentowany jako kompletny proces rozpoczynający się od pozyskania obrazów, który jest ukończony wraz z utworzeniem fotorealistycznego modelu 3D, w tym samym środowisku programowym. Eksperymenty przeprowadzono na wybranych obiektach bliskiego zasięgu, z odpowiednio wykonaną geometrią zdjęć, tworzących pierścień (okrąg) wokół mierzonego obiektu. Do automatycznego dopasowania punktów, wykrytych algorytmem SUSAN, wykorzystano metodę Area Base Matching (CC/LSM), algorytm RANSAC wykorzystując rachunek tensorowy. Rekonstrukcja powierzchni generowania modelu jest jednym z bardzo ważnych etapów modelowania 3D. Rekonstrukcja precyzyjnych powierzchni na podstawie nieregularnej chmury punktów uzyskanych z automatycznego opracowania obrazów cyfrowych jest zagadnieniem otwartym. Tworzenie wielokątnych modeli, które mogą sprostać wysokim wymaganiom w zakresie modelowania i wizualizacji, potrzebne jest w wielu aplikacjach. Metoda wielokątów jest zwykle idealna drogą do dokładnego reprezentowania wyników pomiarów, a jednocześnie do uzyskania optymalnego opisu powierzchni. Przetestowano trzy algorytmy: metodę objętościową (VCG), metodę Poissona i metodę Ball Pivoting. Metody te są najczęściej stosowane do modelowania jednorodnej siatki punktów. Wyniki eksperymentów wykazały, że niewłaściwe zastosowanie tych metod powoduje różne artefakty i zniekształcenia powierzchni modelu. Po utworzeniu siatki trójkątów modelowanej powierzchni, wyniki zwizualizowano wykorzystując metodę cieniowania oraz teksturowanie chmury punktów. Dokładność uzyskanej rekonstrukcji powierzchni modelu uzyskano z poniżej 1 mm.

7

A System for Reconstruction of Solid Models from Large Point Clouds

Hussein A. S.

Machine Graphics and Vision

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2009

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Vol. 18, No. 3

321-344

EN

This paper presents an integrated system for reconstructing solid models capable of handling large-scale point clouds. The present system is based on new approaches to implicit surface fitting and polygonization. The surface fitting approach uses the Partition of Unity (POU) method associated with the Radial Basis Functions (RBFs) on a distributed computing environment to facilitate and speed up the surface fitting process from large-scale point clouds without any data reduction to preserve all of the surface details. Moreover, the implicit surface polygonization approach uses an innovative Adaptive Mesh Refinement (AMR) based method to adapt the polygonization process to geometric details of the surface. This method steers the volume sampling via a series of predefined optimization criteria. Then, the reconstructed surface is extracted from the adaptively sampled volume. The experimental results have demonstrated accurate reconstruction with scalable performance. In addition, the proposed system reaches more than 80% savings in the total reconstruction time for large datasets of Ο (10⁷) points.

8

Digital modelling of a human skull

Etxaniz O., Solaberrieta E., Mínguez R., Muniozguren J., Arias A.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 27, nr 1

55-58

EN

Purpose: This paper describes the first step of a project that aims to improve the design and placement of dental prostheses through an in-depth analysis of jaw movement. This analysis requires prior obtaining quality digital models of all elements involved in the movement. The paper describes the process to obtain the digital models through Reverse Engineering techniques, and evaluates their quality. Design/methodology/approach: The process of digitalization of a human skull by means of a hand-held 3D laser scanner has been evaluated to see the suitability of this technique. A skull has been chosen as test element as it has several characteristics that make its digitisation by optical techniques difficult, such as a non-uniform surface and a complex geometry. The surfaces obtained by the scanner have been edited by point cloud edition software. Findings: Reverse Engineering optical hardware has several limitations to correctly digitize complex geometries, but these deficiencies can be solved using the Reverse Engineering software properly. Research limitations/implications: The same analysis should be performed by point clouds obtained through other Reverse Engineering technologies, such as structured light scanners. These technologies can achieve best values of accuracy and resolution, so that both results should be compared. Practical implications: This paper gives the chance to apply Reverse Engineering techniques to achieve high quality digital models of free form complex geometries. The constraints presented by optical digitization technologies can be solved through powerful point cloud edition software. Originality/value: This paper describes the process of digitalization of complex free form geometries and the subsequent point cloud edition.

9

Frequency-based representation of 3D point-based surfaces using spherical harmonics

Mousa M., Chaine R., Akkouche S.

Machine Graphics and Vision

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2006

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Vol. 15, No. 3/4

537-546

EN

In this paper, we propose a precise frequency-based representation for oriented point-based surfaces using spherical harmonics. The representation can be useful in many applications, such as filtering, progressive transmission and coding of 3D surfaces. The basic computation in our approach is the spherical harmonics transform of local spherical radial functions induced by a set of points. An important feature of our approach is that the calculations are performed directly on local 2D triangulations of the point-based surface without any prior space voxelization. This property ensures that the complexity of our computation of the spherical harmonics transform is linear in the number of triangles in the local patch. We present some experimental results which demonstrate our technique.

10

The Effect of Propanal on the Stability Range of the Reconstructed Au(100) Surface in Different Electrolytes

Skołuda P.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 4

583-589

EN

Voltammetric measurements have been employed to assess the effect of propanal on the stability range of the reconstructed Au(100) surface in different electrolytes. The results show that, depending on the type of anions, propanal reduces or increases or does not change the stability range of the reconstructed surface. The influence of the propanal electrooxidation on this stabilization is considered.

11

A robust technique for surface reconstruction from orthogonal slices

Sviták R., Skala V.

Machine Graphics and Vision

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2004

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Vol. 13, No. 3

221-233

EN

The problem of surface reconstruction from sets of planar slices representing cross sections through 3D objects is presented. The final result of surface reconstruction is always based on the correct estimation of the structure of the original object and on the visual quality of the resultant surface. This paper is a case study of the structure reconstruction and the surface formation problems. We present a new approach, which is based on considering mutually orthogonal sets of slices. A new method for surface reconstruction from orthogonal slices is described, and the benefit of orthogonal slices is also discussed. The properties and sample results are presented as well. Key words: surface reconstruction, orthogonal slices, orthogonal cross-sections, contour correspondence.

12

Complex approach to surface reconstruction of microscopic samples from bimodal image stereo data

Jan J., Janova D.

Machine Graphics and Vision

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2001

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Vol. 10, No. 3

261-288

EN

The paper describes a set of approaches and mathods enabling robust and relatively precise stereo-analysis-based surface reconstruction in scanning electron microscopy(SEM). The paper primarily deals with the disparity analysis problem, namely with selection of a suitable similarity criterion to be used for finding image correspondences. The search-and-match method (as opposed to feature-based analysis) is shown as probablyn the only practical solution in the given environment of SEM when no prior constraints on the surface type are allowed. Extensive comparison of some common and newly suggested similarity criteria lead to the conclusion that the designed angle criterion is the only one acceptable so far with respect to the error rate. Use of the criterion has been shown equivalent to applying a non-linear two-dimensional matched filter, which enables efficient frequency domain implementation in the form of a linear matched filter modification. An important improvement in reliability of the computed disparities has been achieved by using both available imaging modalities (back-scattered electrons - BEI and secondary electrons - SEI), thus providing vector image data. Expressing the criterion for the vector case in terms of both individual scalar cases cuts computational requirements by half, besodes allowing for an additional reliability criterion - comaprison of three different, though partly, dependent criteria. Secondly, the comprehensive approach includes also solution of problems which may seem marginal but are important for the practical success of the analysis. Recent improvements, solving some of such specific problems of SEM stereo analysis, are discussed as well. The paper summarises the present state of the method's development over the past few years partial descriptions of which can be found scattered in previous publication devoted to individual specific problems.

13

Optimal blocs subdivision in the "Dividing-cubes" algorithm : application to the 3D medical imagery

Kebaili A., Boumghar F.

Machine Graphics and Vision

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2000

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Vol. 9, No. 1/2

281-288

EN

In this article we present an optimisation of the execution time of the "dividing-cubes" alorithm. whose aim is to extract 3D surfaces from volumic images. These images are generally very voluminous and represents an pile up of many iso-surfaces, what require a considerable time to process them fpr extract the desired iso-surface. In first time it's matter of reducing the cover time of the 3D image by subdividing it into blocs of voxels, witch comes to visits a more reduce number of voxels. We propose in a second step, an optimization of the subdividing blocs parameters that allow us to have a bloc size the most suitable as possible, and permint to genetare a minimal execution time.Our propositions and formulations are made vaild by means of experiments carried out on processed images, and medical images.

14

Rekonstrukcja powierzchni ściany (100) monokryształu złota w środowisku elektrochemicznym

Skołuda P.

Wiadomości Chemiczne

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1999

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[Z] 53, 1-2

115-133

EN

The low-index single crystal surfaces of gold and platinum are known to reconstruct under ultra-high-vacuum conditions. It has been demonstrated that many of these reconstruction phenomena can also be observed for the metal surface in contact with an electrolyte. The data presented will focus on the surface reconstruction of Au(100) electrode in view of the results of recent electochemical studies. We shall describe the preparation and the conditions under which Au(100)-(hex) surface is stable in solution. Flame annealed Au(100) surface is reconstructed and it is demonstrated under what conditions this initial (thermally induced) reconstruction is preserved during and after the contact with an electrolyte. The so-called charge-induced reconstruction and its influence on electrochemical adsorption reactions is presented. The kinetics studies of surface structural transition due to charge-induced reconstruction or anion-induced lifting of the reconstruction are discussed in some detail. Finally, the role of the surface charge and the coverage of the adsorbate in the lifting of the reconstruction of Au(100) surfaces is briefly discussed.

15

Surface strain during homoepitaxy : growth and ion ablation of CdTe

Tatarenko S., Etgens V. H., Hartmann J. M., Martrou D., Arnoult A., Cibert J., Magnea N., Sauvage-Simkin M., Alvarez J., Ferrer S.

Opto-Electronics Review

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1999

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Vol. 7, No. 2

75-80

EN

Oscillations of the surface lattice parameter were observed by RHEED during the homoepitaxial growth of (001) CdTe by molecular beam epitaxy (MBE) and atomic layer epitaxy (ALE). The oscillations are associated to a deformation, induced by the surface reconstruction, at the free edges of the small 2D islands formed during the growth. In the same way, a lateral relaxation is measured during the layer by layer "de-growth" of (001) CdTe. Experiments using a CCD X-ray sensitive camera combined with the very bright X-ray beam offered by the European Synchrotron Radiation Facility allowed us to investigate the two layers behaviour of the CdTe surface in real time during the ablation by ion sputtering. The results show a relaxation mechanism, which is effective only whem islands are presented on the surface. A correlation has been found between the size the islands, their distribution, and the surface reconstruction. Particularly, a long-distance correlation between islands along the [1-10] direction has been observed.