Journal Issue: Научная визуализация
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Volume
2024-16
Number
1
Issue Date
Journal Title
Journal ISSN
2079-3537
Том журнала
Том журнала
Научная визуализация
(2024-16)
Статьи
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Modifications of Classical Surface Reconstruction Algorithms for Visualization of a Function Defined on a Rectangular Grid
(НИЯУ МИФИ, 2024) Munts, N. V.; Kumkov, S. S.
In the paper, modifications of visualization algorithms for real-valued functions of two and three arguments given on a rectangular or parallelepipedal grid are considered. In the case of two arguments, the graph of the function is a surface embedded into the three-dimensional space. The majority of scientific visualization systems offer visualization procedures for such surfaces, but they construct them under the assumption that the functions are continuous. In the paper, for the case of a discontinuous function, a modification of this algorithm is proposed. In addition, the algorithm removes “plateaus” that occur after cutting the function at some level (in order to remove too large values).
Visualization of a function of three arguments implies showing its level sets, that is, regions of the space of arguments where the magnitudes of the function do not exceed a certain value. In the case of a grid function, such sets are “voxel” sets, that is, they are composed of grid cells. With that, some smoothing of the surface of such sets is required, which is carried out by the Marching Cubes algorithm and algorithms of the Laplacian family. A modification of the Marching Cubes algorithm is proposed, which preserves the symmetry of the set surface with respect to the coordinate planes, axes, or some point, if the rendered set has such a symmetry.
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Possibility of Using the Gershberg-Papoulis Method in the Problem of Phase Structure Reconstructing from Low-angle Hilbertograms
(НИЯУ МИФИ, 2024) Arbuzov, E. V.; Arbuzov, A. V. ; Dubnishchev, Yu. N.; Zolotukhina, O. S.; Lapikov, M. M.; Lukashov, V. V.
The possibility of processing small-view hilbertograms by the Gershberg-Papulis method to restore the refractive index of phase objects is discussed. The method consists in iterative transitions from estimating a function in the Fourier plane to estimating it in a coordinate space with an adjustment using a priori information. The spectrum of the function is determined on the entire frequency plane as an iterative process result Numerical simulation of the refractive index reconstruction for various test functions was performed using the Gershberg-Papulis method using Radon data known for four angles. Experimental studies on the Hilbert diagnostics example of reacting media (flames) in a high-speed shooting mode (up to 2000 frames per second) were performed using a four-angle tomographic complex implemented on the basis of an upgraded IAB-463M shadow device.
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Structure Visualization of 4-DASPI–Cucurbituril Supramolecular Complex to Predict the Solvatochromic Shift of Absorption Spectrum
(НИЯУ МИФИ, 2024) Stepko, A. S.; Lebedev-Stepanov, P. V.; Лебедев-Степанов, Петр Владимирович
The study of supramolecular “host-guest” complexes in solutions is of fundamental and practical significance. The structures and formation enthalpy of supramolecular complexes for the 4-DASPI dye with two cavitands (cucurbit[6]uril and cucurbit[7]uril) have been obtained by the TDDFT quantum chemistry method with a camb3lyp basis. It was shown by visualization of the structures that the size of cucurbit[6]uril is too small and doesn’t allow the dye chromophore to penetrate into the cavitand cavity while the dye stays in the ground state, but the formation of an external complex is possible. On the contrary, formation of an inclusion complex with the cucurbit[7]uril is energetically favorable, and the dye chromophore penetrates into the cavity. Visualization of the complex structure allows us to determine the chromophore position relative to the given cavitand cavity, and thus we can predict the changes in the dye spectra due to complexation. The theoretical results of the work are in good correlation with the experiment.
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Building Depth Maps Using an Active-Pulse Television Measuring System in Real Time Domain
(НИЯУ МИФИ, 2024) Kapustin, V. V.; Tislenko, A. A.; Movchan, A.; Zabuga, S. A.
The paper presents the results of software development for building depth maps based on video data from a television camera of an active-pulse television measuring system (AP TMS) in real time domain. The development of such software is required to conduct various scientific studies, as well as to improve the methods and techniques for building depth maps and remote measurement of the characteristics of objects of interest. The software was implemented using the Python programming language with additional libraries installed. According to the results of testing the implemented algorithm, it was found that the calculation speed using the graphics processing unit (GPU) is on average 3.5 times higher than the speed of the algorithm using only the central processing unit (CPU). It has been established that with the help of CUDA cores it is possible to build depth maps in real time domain at the maximum possible resolution of video frames of the system (1544x2064 pixels), while when using the central processor, real-time operation is possible only at a reduced resolution of video frames (772x1032 pixels).
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Visualization of Flow of a Viscous Incompressible Fluid Corresponding to Exact Solutions of the Navier-Stokes Equations
(НИЯУ МИФИ, 2024) Galkin, V. А.; Dubovik, A. O.; Morgun, D. A.
The work visualizes flows corresponding to the exact solutions of the system of hydrodynamic equations previously published by the authors, consisting of the vector Navier-Stokes equation and the law of conservation of mass for an incompressible fluid. This work uses the MathGL library for the C/C++ language and ParaView for scientific visualization of the results of numerical and analytical calculations. Without the use of such means, it would be impossible to see that the fluid flow is stratified into invariant subregions, and the trajectories of motion of fluid particles are wound on torus-shaped surfaces.
Most of the scientific works on the study of hydrodynamic equations cover the results of calculations and do not address the questions of the existence of exact analytical solutions. At the same time, these calculations are performed with a specially selected set of fitting parameters unique to the equipment used and the computer software used. Questions about trust in the results of such calculations, their verification with exact solutions and the creation of a bank of test examples of applied problems in order to certify the applicability of the calculation results in practice become relevant.