Kolb, Andreas
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Publication Access status: Open Access , ATHENA Research BookThe ATHENA European University is an alliance of nine Higher Education Institutions with the mission of fostering excellence in research and innovation by facilitating international cooperation. The ATHENA acronym stands for Advanced Technologies in Higher Education Alliance. The partner institutions are from France, Germany, Greece, Italy, Lithuania, Portugal, and Slovenia: the University of Orléans, the University of Siegen, the Hellenic Mediterranean University, the Niccolò Cusano University, the Vilnius Gediminas Technical University, the Polytechnic Institute of Porto, and the University of Maribor. In 2022 institutions from Poland and Spain joined the alliance: the Maria Curie-Skłodowska University and the University of Vigo. This research book presents a selection of the ATHENA university partners' research activities. It incorporates peer-reviewed original articles, reprints and student contributions. The ATHENA Research Book provides a platform that promotes joint and interdisciplinary research projects of both advanced and early-career researchers.Source Type:Book292 404 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Decoupled Boundary Handling in SPH(2023); PArticle-based boundary representations are frequently used in smoothed pArticle hydrodynamics (SPH) due to their simple integration into fluid solvers. Commonly, incompressible fluid solvers estimate the current density and corresponding forces in case the current density exceeds the rest density to push fluid pArticles apart. Close to the boundary, the calculation of the fluid pArticles’ density involves both neighboring fluid and neighboring boundary pArticles, yielding an overestimation of density, and, subsequently, wrong pressure forces and wrong velocities leading to the disturbed fluid pArticles’ behavior in the vicinity of the boundary. In this paper, we present a detailed explanation of this disturbed fluid pArticle behavior, which is mainly due to the combined or coupled handling of the fluid–fluid pArticle and the fluid–boundary pArticle interaction. We propose the decoupled handling of both interaction types, leading to two densities for a given fluid pArticle, i.e., fluid-induced density and boundary-induced density. In our approach, we alternately apply the corresponding fluid-induced and boundary-induced forces during pressure estimation. This separation avoids force overestimation and reduces unintended fluid dynamics near the boundary, as well as a inconsistent fluid–boundary distance across different fluid amounts and different pArticle-based boundary handling methods. We compare our method with two regular state-of-the-art methods in different experiments and show how our method handles detailed boundary shapes.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Evaluation of pArticle‐based smoothed pArticle hydrodynamics boundary handling approaches in computer animationBoundary handling is an important aspect of fluid simulation, and several boundary handling approaches exist in smoothed pArticle hydrodynamics (SPH), which have individual strengths and weaknesses. However, comparing different boundary handling approaches is challenging as there is no common basis for evaluations, that is, no universal set of experiments with quantitative evaluation across different methods, especially within computer animation where many evaluations rely mainly on visual perception. This Article proposes a set of experiments to aid the evaluation of the main categories of fluid‐boundary interactions that are important in computer animation, that is, no motion (resting) fluid, tangential and normal motion of a fluid with respect to the boundary, and a fluid impacting a corner . We propose ten experiments, comprising experimental setup and quantitative evaluation with optional visual inspections, that are arranged in four groups which focus on one of the main category of fluid‐boundary interactions. We use these experiments to evaluate three pArticle‐based boundary handling methods, that is, pressure mirroring, pressure boundaries, and moving least squares pressure extrapolation, in combination with two incompressible SPH fluid simulation methods, namely IISPH and DFSPH, to establish a quantifiable relation between different combinations of boundary handling with simulation approaches and the main categories of fluid‐boundary interactions. Finally, we summarize all results in a rating table and show how our experiments can be used to determine the promising method for specific requirements regarding a given constellation of fluid‐boundary interaction.Source Type:ArticleDOI:10.1002/cav.21383 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Hashed, binned A-buffer for real-time outlier removal and rendering of noisy point clouds(2023); Typical point-based rendering algorithms cannot directly handle large outliers or high amounts of noise without either a costly pre-processing of the point cloud or using multiple render passes. In this paper, we propose an A-buffer-based approach that directly renders unprocessed point clouds and filters out outliers in real time, without introducing additional render passes. The core concept of our approach uses bins along each pixel ray in which intermediate information is accumulated. To improve storage efficiency, we extend the binned A-buffer approach using per-ray bin hashing. Our method significantly improves visual quality when rendering noisy point clouds with varying noise levels and large outliers, while only requiring little performance and memory overhead compared to traditional point rendering methods.Source Type:Article2 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Pacemod: parametric contour-based modifications for glyph generation(2023); ; Metaphoric glyphs are intuitively related to the underlying problem domain and enhance the readability and learnability of the resulting visualization. Their construction, however, implies an appropriate modification of the base icon, which is a predominantly manual process. In this paper, we introduce the parametric contour-based modification (PACEMOD) approach that lays the foundations of automated, controllable icon manipulations. Technically, the PACEMOD parametric representation utilizes diffusion curves, enriched with new degrees of freedom in arc-length parameterization, which allows for manipulation of the icon contours’ geometry and the related color attributes. Moreover, we propose an implementation of our generic approach for a specific, automated design of metaphoric glyphs, based on periodic, wave-like contour modifications. Finally, the practicality of such periodic contour modifications is demonstrated by two visualization examples, which comprise uncertainty visualization of a rain forecast and gradient glyphs applied to COVID-19 data. In summary, with the PACEMOD approach we introduce an instrument that facilitates a user-centered design of metaphoric glyphs and provides a generic basis for potential further implementations according to specific applications.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , PATTERN RECOGNITION OF ROUGH SURFACES BY USING GONIOMETRIC SCATTERED LIGHT(2018); Nowadays, most techniques for evaluating rough metal surfaces are based on tactile or confocal measurement procedures.However, these technologies have disadvantages in respect to measuring speeds, resistance to vibration, impact and dust.In this paper we present a novel surface measurement approach, which uses the scattering light technology.Our approach enhances the state-of-the-art scattering light-based surface measurement methodology in both the detector setup and evaluation of the raw intensity values acquired by the scattered light device.The main goal in optimizing the measurement setup is to capture scattering parameters for rough surfaces in a range greater than 10 µm based on an enlarged detector array.Regarding the evaluation, we propose a pattern recognition approach which maps the reflection intensity I back to material structures and the tenpoint mean roughness Rz, the golden standard in tactile roughness characterization.Based on this approach, we are able to classify rough surface deviations like stripes using a simple but robust thresholding.In order to demonstrate the generality of our approach, we evaluate our approach using two rather different materials, i.e. brushed stainless steel and anodized aluminium.Source Type:ArticleDOI:10.24425/1181603 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Pulse based Time-of-Flight range sensing(2018); ; Pulse-based Time-of-Flight (PB-ToF) cameras are an attractive alternative range imaging approach, compared to the widely commercialized Amplitude Modulated Continuous-Wave Time-of-Flight (AMCW-ToF) approach. This paper presents an in-depth evaluation of a PB-ToF camera prototype based on the Hamamatsu area sensor S11963-01CR. We evaluate different ToF-related effects, i.e., temperature drift, systematic error, depth inhomogeneity, multi-path effects, and motion artefacts. Furthermore, we evaluate the systematic error of the system in more detail, and introduce novel concepts to improve the quality of range measurements by modifying the mode of operation of the PB-ToF camera. Finally, we describe the means of measuring the gate response of the PB-ToF sensor and using this information for PB-ToF sensor simulationSource Type:Article553 371