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1
Content available Modeling and rendering of convective cumulus clouds for real-time graphics purposes
Kobak P., Alda W.
Computer Science
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2017
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Vol. 18 (3)
241--268
EN
The paper presents a simulation and rendering model of three dimensional covective cloud evolution. The model is physically based, however its purpose is graphical. The main stress is put on balancing two parts of a model: the atmsphere simulation with convective motion of air and water vapor combined with rendering of semi-transparent and light-scattering clouds, in order to achieve realistic animation in real-time. We examine and compare two algorithmic approaches based on CPU and GPU computations.
2
Content available remote Realistic model of spine geometry in the human skeleton in the VICON system
Długosz M., Chwała W., Maciejasz P., Alda W.
Bio-Algorithms and Med-Systems
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2012
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Vol. 8, no. 1
123--132
EN
The human spine is definitively one of the most important parts of a living body. From biomechanical point of view, this organ is the most complicated structure, and a dynamic analysis of its motion still requires more detailed models be created. The aim of this study is to build an accurate computer model of the geometry of the spine and insert it into available skeleton models, used in Vicon. Up to now such models were simplified and that is why they were not sufficient for research of detailed motion of the spine. The paper describes the process of creating models of the vertebrae. During research, authors simultaneously used two techniques: 3D scanning of the vertebrae and computed modeling in 3D graphics software. A universal data format: .obj used to keep the information about surface shape of an object, its colour, texture etc. is presented in detail. In a discussion on Vicon data formats and relations between them, several file types are taken under consideration: marker files: .mkr, global model parameters files: .mp, files of the model structure: .mod. But first of all, step-by-step instructions of how to connect the files with geometrical objects for the visualization purposes, are presented.
3
Content available remote A GPU-based method for approximate real-time fluid flow simulation
Rożen T., Boryczko K., Alda W.
Machine Graphics and Vision
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2008
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Vol. 17, No. 3
267-278
EN
Fluid flow can be realistically simulated by physical models. We present a method for simplifying the Navier-Stokes equations by relaxing the incompressibility constraint. Our method allows for low-cost real-time simulation of two-dimensional fluid flow with accuracy sufficient for computer graphics. The implementation takes advantage of recent programmable floating-point graphics hardware, which performs all the necessary computations.
4
Content available Optimization of frequency filtering in random access JPEG library
Radziszewski M., Alda W.
Computer Science
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2008
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Vol. 9
109-120
EN
In the paper we present a method of direct access to single blocks of JPEG files which contain textures, with on-the-fly decompression. Anisotropic, adaptive filtering is applied in order to minimize visual defects appearing mainly on blocks borders. Main purpose of the method is to enable fast extraction of only these parts of an entire image which arę currently needed and not to keep whole decompressed texture in the main memory. This approach enables effective usage of high quality textures with Iow memory consumption. It's benefits are mainly demonstrated in rendering complex 3D scenes using nondeterministic ray-tracing algorithm. The algorithms have been encapsulated into DLL and static library.
PL
W artykule przedstawiono metodę swobodnego dostępu do pojedynczych bloków obrazów JPEG zawierających tekstury, z dekompresją, wykonywaną na bieżąco. Zastosowane przy tym anizotropowe adaptacyjne filtry zostały dobrane pod kątem minimalizacji obserwowanych zniekształceń, pojawiających się głównie na granicach bloków. Głównym celem zaproponowanej metody jest umożliwienie szybkiego dostępu tylko do tych fragmentów obrazu, które aktualnie są wymagane, bez konieczności przechowywania całej zdekompresowanej tekstury w pamięci komputera. Takie podejście pozwala na efektywne użycie dużych tekstur o wysokiej rozdzielczości przy oszczędnym wykorzystaniu pamięci. Swoje zalety demonstruje głównie w renderowaniu scen 3D przy użyciu metody śledzenia promieni. Zaproponowane algorytmy zostały wbudowane w bibliotekę typu DLL i statyczną.
5
Content available remote Nowa metoda modelowania morfogenezy otwornic
Tyszka J., Topa P., Łabaj P., Alda W.
Przegląd Geologiczny
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2004
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Vol. 52, nr 1
80-83
EN
An overview of modeling methods of invertebrate shells as a background for modeling and visualization of mineral shells of foraminifera is presented. The recent authors propose more realistic methods of modeling. Our model introduces the moving reference approach to theoretical modeling of foraminiferal shells. This approach uses apertures as reference points, which move together with step-by-step growing chambers. Another important aspect of simulation is a random selection of parameters from the defined ranges of values. The resulted ``theoretical shells’’ closely mimic morphology and variability of recent and fossil foraminifera. The model is presented as an applet at http://www.icsr.agh.edu.pl/foraminifera . Future prospect includes an “emergent model”, gaining deeper insight into real morphogenetic processes.
6
Simulation and experimental studies of the process of filling porous materials
Górny Z., Kluska-Nawarecka S., Połcik H., Alda W.
Archives of Metallurgy
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2003
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Vol. 48, iss. 3
261-267
EN
The article shows the results of simulation studies conducted on metal matrix composites applying the method of the dynamics of molecular particles. the described method has been illustrated with numerical examples of the simulation and verified by experiments. The numerical computations have made on supercomputers available at the Academic Computer Centre in Kraków, while experimental studies were conducted by the Foundry Research Institute in Kraków.
PL
W pracy przedstawiono wyniki badań symulacyjnych kompozytów metalowych stosując metodę dynamiki cząstek molekularnych. Prezentowana metoda jest zilustrowana przykładami numerycznych symulacji oraz weryfikowana doświadczalnie. Obliczenia numeryczne prowadzono na superkomputerach w Akademickim Centrum Komputerowym w Krakowie, natomiast badania eksperymentalne zrealizowano w Instytucie Odlewnictwa w Krakowie.
7
Content available Simulation of fluid flow with interacting particles
Górecki R., Mars M., Alda W., Fioretti L., Rybicki J.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2001
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Vol. 5, No 1
59-69
EN
In the paper a method for modeling flows in the presence of interacting particles is briefly presented. The method is based on merging classical, continuous approach of numerical solution of Navier-Stokes equations on the 2D mesh with discrete particles interacting with the fluid and among themselves by means of central and friction forces. Several sample simulations have been described presenting the flow through porous medium and convection flow driven by sedimentation.
8
Content available 2D simulations of liquid percolation through model porous media: preliminary MD and DPD results
Rychcik M., Bośko J., Rybicki J., Alda W., Dzwinel W., Mancini G., Fioretti L.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2001
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Vol. 5, No 1
85-97
EN
In the paper we make a short overview of computer models based on particle approach, which can be suitable for the simulation of fluid flow through porous media. We concentrate on Molecular Dynamics (MD) and Dissipative Particle Dynamics (DPD) methods. We describe main features of our simulation programs, and present and discuss preliminary results of MD and DPD simulations of 2D fluid flow through a simple model rigid porous media. The paper aims at the evaluation of the applicability of MD and DPD methods for simulations of liquid flows in media of complicated geometry.
9
Large scale computing as a vehicle for studies in computational and computer sciences
Kitowski J., Alda W., Boryczko K., Bubak M., Dzwinel W., Funika W., Mościński J., Nikolow D., Pogoda M., Słota R., Wcisło R
Zeszyty Naukowe Uniwersytetu Jagiellońskiego. Prace Informatyczne
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2000
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z. 10
51-68
EN
In this paper we present some methods and algorithms for large scale computing which cover different areas of computational and computer sciences. They concern particle models, CFD computing, animation, monitoring and predicting of application performance as well as scientific visualization and scientific data storing and retrieving.
10
Content available Short- and medium-range order in bismuth-silicate glasses: a solecular dynamics study
Witkowska A., Rybicki J., Laskowski R., Mancini G., Feliziani S., Alda W.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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1999
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Vol. 3, No 2
239-254
EN
We report on the results of classical molecular dynamics (MD) simulations of str ucture of amorphous 15 Bi2O3 85 SiO2 [% mol] and 40 Bi2O3 60 SiO2 [% mol], and their totally reduced forms, 15 Bi2 85 SiO2 [% mol], and 40 Bi2 60 SiO2 [% mol], respectively. The simulations have been perfo rmed in the isobaric-isoenthalpic ensemble, using a two-body interaction potential. The set of the potential parameters was constructed as a suitable com bination of the parameters which were previously proposed for pure Bi2O3, and SiO2. Both unreduced, and reduced sy stems were initially prepared as well equilibrated hot melts, and then slowly co oled down to 300K. The structural information from the MD simulations was obtained from radial and angular distribution functions, static structural factors, Voronoi polyhedra sta tistics, and ring analysis. The simulation results can be summarised as follows. In unreduced glass with 15% [mol] Bi2O3 contents, the silicon structural units (mainly regular tetrahedra) form continuous network, whereas in 40% [mol] Bi2O3 glass these units are disconnected. In both unreduced systems Bi ions have mainly six-fold oxygen co-ordination, and no dominating structural unit can be individuated. However, the distorted bismu th units form a continuous network. In both totally reduced glasses (15% Bi2 85% SiO2, and 40% Bi2 60% SiO2 [% mol]), the silica network is built entirely from corner shari ng SiO4 tetrahedra. The structure of the silica subsystem is similar to that of pure *-SiO2. After the reduction, the Bi-Bi co-ordination significantly increases, whereas the first neighbour distance decreases. Moreover, partial static structural fact ors for Bi-Bi pairs indicate that the medium-range order in reduced glasses exhi bits greater periodicity than in unreduced glasses. Neutral Bi atoms form small clusters within the silica matrix.
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