Sekce matematiky


Recent Submissions

Now showing 1 - 5 of 5
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    Registration of Partially Focused Images for 2D and 3D Reconstruction of Oversized Samples
    (Hindawi, 2017-12-18) Martišek, Dalibor; Druckmüllerová, Hana
    Methods of fracture surface 3D reconstruction from a series of partially focused images acquired in a small field of view (e.g., by confocal microscope or CCD camera) are well known. In this case, projection rays can be considered parallel and recorded images do not differ in any geometrical transformation from each other. In the case of larger samples (oversized for microscope or CCD camera), it is necessary to use a wider viewing field (e.g., standard cameras); taken images primarily differ in scaling but may also differ in shifting and rotation.These images cannot be used for reconstruction directly; they must be registered; that is, we must determine all transformations in which the images differ and eliminate their effects.There are several ways to do this. This paper deals with the registration based on phase correlation.
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    The Enhancement of 3D Scans Depth Resolution Obtained by Confocal Scanning of Porous Materials
    (De Gruyter Open, 2017-11-24) Martišek, Dalibor; Procházková, Jana
    Scans of porous materials such as concrete ofr cement paste are highly problematic due to its low depth resolution. We propose an averaging method based on the Lindeberg-Levi theorem that improves the final depth resolution.
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    3D Reconstruction of the Surface using a Standard Camera
    (Hindawi ltd, England, 2017-12-17) Martišek, Dalibor
    This paper deals with 3D reconstructions of series of partially focused images. Some of these methods are known in case of images which were acquired is small field of view.
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    Joint Rock Coefficient Estimation Based on Hausdorff Dimension
    (Scientific Research Publishing, 2017-12-18) Martišek, Dalibor
    The strength of rock structures strongly depends inter alia on surface irregularities of rock joints. These irregularities are characterized by a coefficient of joint roughness. For its estimation, visual comparison is often used. This is rather a subjective method, therefore, fully computerized image recognitionprocedures were proposed. However, many of them contain imperfections, some of them even mathematical nonsenses and their application can be very dangerous in technical practice. In this paper, we recommend mathematically correct method of fully automatic estimation of the joint roughness coefficient. This method requires only the Barton profiles as a standard.
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    Notes on iterative closest algorithm
    (Institute of Mathematics and Physics, Faculty of Mechanical Engineering, Slovak University of Technology in Bratislava, 2018-03-23) Procházková, Jana; Martišek, Dalibor
    Point clouds are commontly used in many areas of technical practice. Nowadays, the common applications are in area of autonomous cars and 3D terrain or object modelling. During the scanning process, the scanning device or object is moving. So, the problem of precise point cloud registration arises. In this article, we describe Iterative Closest Point (ICP) algorithm that is suitable for fine registration. We introduce some of the improvements that leads to higher precision, speed computation and efficiency.