Leonid I. Dimitrov

Austrian Academy of Sciences

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MŠ

Miloš Šrámek

Austrian Academy of Sciences

Emanuel Wenger

Austrian Academy of Sciences

M. G. Mozerov

Institute for Information Transmission Problems

ВН

В. Н. Карнаухов

Institute for Information Transmission Problems

Nikolay S. Merzlyakov

Institute for Information Transmission Problems

Jakob Andreas Bærentzen

Technical University of Denmark

Viliam Solčány

Austrian Academy of Sciences

G Partsch

Ludwig Boltzmann Institute for Digital Health and Prevention

Igor Holl�nder

Austrian Academy of Sciences

Luis Weruaga

Khalifa University of Science and Technology

Cooperative Institutions

Austrian Academy of Sciences

University of Vienna

Institute for Information Transmission Problems

Ludwig Boltzmann Institute for Digital Health and Prevention

Seibersdorf Laboratories (Austria)

TU Wien

Russian Academy of Sciences

Kaiser-Franz-Josef-Spital

Medical University of Vienna

Ludwig-Maximilians-Universität München

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Bone Segmentation in CT Angiography Data Using a Probabilistic Atlas.

Vision Modeling and Visualization (2003)

Matús Straka Alexandra La Cruz A. Köchl Leonid I. Dimitrov Miloš Šrámek

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Citations (14)

<title>Pseudo-colored visualization of EEG activities on the human cortex using MRI-based volume rendering and Delaunay interpolation</title>

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (1995)

Leonid I. Dimitrov

A method for a pseudo-colored smooth representation of evaluated EEG parameters on a three-dimensional reconstruction of a proband's cortex is proposed. The EEG data are obtained through standard measurements and are subsequently Fourier analyzed in order to transform them to parameters representing the signals' power and coherence changes with respect to the averaged EEG at rest. The morphological data for the 3D-reconstruction of the brain is gained through MRI-scans of the head. The three-dimensional reconstruction of the cortex is achieved by means of a graylevel gradient shading method. During rendering, each brain surface voxel (volume element) is associated with a suitable parameter value determined through an inverse distance-weighted interpolation scheme from the values evaluated for its neighbors in the Delaunay triangulation mesh between the electrodes. Following the interpolation, a mapping of the calculated surface value in the HSV color space is employed in order to achieve an expressively colored brain surface with well perceptible distinct activation regions and smooth transitions between them. The presented method provides a possibility for direct, visual comparisons of the activated brain regions of a healthy individual.

Interpolation

Surface reconstruction

10.1117/12.207641

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Citations (6)

Correction of Voxelization Artifacts by Revoxelization

Eurographics (2001)

Miloš Šrámek Leonid I. Dimitrov Jakob Andreas Bærentzen

Alias

10.1007/978-3-7091-6756-4_18

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Citations (2)

The Spectral Nature of Maximum Likelihood Noise Compensated Linear Prediction

IEEE Transactions on Audio Speech and Language Processing (2013)

Luis Weruaga Leonid I. Dimitrov

The effects of noise in autoregressive (AR) analysis (or linear prediction) and its compensation (NCAR) has been commonly carried out in the time domain under the least square (LS) criterion. This paper studies the adequacy of such an approach by means of a comparative analysis with selected frequency-based NCAR methods. In particular, the maximization of the spectral likelihood (ML) results in a proper optimization problem that is easy to solve and brings useful insights into the rationale of the NCAR problem. On the contrary, popular time-based NCAR methods are shown in the paper to be designed, in the ML context, around ill-conditioned criteria, requiring constraints to guarantee stable solutions. The statistical analysis on a realistic scenario as well as an experiment on speech enhancement complement this analysis.

Complement

Maximization

10.1109/tasl.2013.2255277

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Citations (4)

<title>Visualizing different kinds of 3D data sets in a uniform and comprehensive manner</title>

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (1995)

Leonid I. Dimitrov Igor Hollaender Miloš Šrámek

In our work, we present a method and an interactive program resulting from it for visualizing and manipulating different three-dimensional data sets in a consistent way. After an introductory discussion of the motivation which initiated the ongoing research, a short description of the program ensues. A section devoted to different uses of the program in a few chosen domains illustrates the applicability of the program to the manifold issues encountered in diverse visualization situations nowadays.

Section (typography)

Manifold (fluid mechanics)

10.1117/12.199637

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The reflection of cognitive tasks in EEG and MRI and a method of its visualization

Brain Topography (1997)

Igor Holl�nder Helmuth Petsche Leonid I. Dimitrov Oliver Filz Emanuel Wenger

Schematic

10.1007/bf01190387

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Citations (13)

<title>Object-oriented design and implementation of VORTEX--a C++-class library with Tcl-interface for volume visualization</title>

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (1998)

Leonid I. Dimitrov

This paper describes the design and implementation of VORTEX, a software package for generating high-quality images depicting shadowed and colored/textured representations of objects inherently present in a volumetric data set. It is realized as a C++-class library, provided with an API, and suited for inclusion in customized programs. Besides, VORTEX features a Tcl- interface allowing for interactive execution or preparation of scripts for calculating longer image sequences under controlled alteration of the viewing and/or rendering parameters. Specialties of the package include oversampling in image and object space, voxel traversal acceleration, dynamic adaptation of the ray/surface intersections, depth- dependent transparency, higher order gray level gradient approximations, arbitrarily orientable cut planes, and texture-mapped surface colorations. The design of the class library adheres strictly to the object-oriented paradigm which enables easy alteration and/or adaptation of additional classes and objects. The source and header files of the library are extensively documented according to an own scheme allowing for automatic generation of man-pages and Tcl-wrappers for the Tcl-interpreter by means of a suite of proprietary Perl-scripts. A practical application of VORTEX to a brain physiology problem is discussed at the end of the paper.

Perl

Header

10.1117/12.301365

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Citations (1)

Resampling structured grids into regular ones

Eurographics (2003)

Leonid I. Dimitrov Aleksej Kolcun Miloš Šrámek

Resampling

10.2312/egp.20031014

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Citations (2)

Texturing 3D‐reconstructions of the human brain with EEG‐activity maps

Human Brain Mapping (1998)

Leonid I. Dimitrov

A method for representing the results of statistical EEG analysis in a visually comprehensive and concentrated way is presented.It consists of a combination of scattered data interpolation, texture mapping, and volume rendering techniques.First, starting with an EEG study of the proband in question, a smoothly interpolated rectangular map of the EEG findings in the (, )-domain ( and denote spherical coordinates) is calculated.Then, using the data from an accompanying MRI scan, volume-rendered representations of the brain with a pseudo-colored cortical surface, vividly depicting the precalculated EEG-activities, are produced.Custom-developed software was used for interpolating the EEG maps from the scattered data samples, as well as for mapping and rendering them together with the brain volume data.The algorithm which achieves the scattered data interpolation is a genuine development employing Delaunay triangulation and a modification of the well-known rotation-invariant Phong interpolation.The pictures produced by the presented method are currently being utilized in neurophysiology for detecting correlations between EEG-parameters, cortical morphology, and underlying mental activities.Hum.

Human brain

Brain mapping

10.1002/(sici)1097-0193(1998)6:4<189::aid-hbm1>3.3.co;2-7

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Citations (2)

Texturing 3D-reconstructions of the human brain with EEG-activity maps

Human Brain Mapping (1998)

Leonid I. Dimitrov

Human brain

Brain mapping

10.1002/(sici)1097-0193(1998)6:4<189::aid-hbm1>3.0.co;2-

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Citations (5)