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- Lindskog, Eric, et al.
(author)
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Generalized Playback Bar for Interactive Branched Video
- 2019
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In: PROCEEDINGS OF THE 27TH ACM INTERNATIONAL CONFERENCE ON MULTIMEDIA (MM19). - New York, NY, USA : ASSOC COMPUTING MACHINERY. - 9781450368896 ; , s. 2369-2377
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Conference paper (peer-reviewed)abstract
- During viewing of interactive branched video, users are asked to make viewing choices that impact the storyline of the video playback. This type of video puts the users in control of their viewing experiences and provides content creators with great flexibility how to personalize the viewing experience of individual viewers. However, in contrast to with traditional video, where the use of a playback bar is default for most - if not all - players, there currently does not exist any generic playback bar for branched video that helps visualize the upcoming branch choices. Instead, most branched video implementations are typically custom-made on a per-video basis (e.g., see custom-made Netflix and BBC movies) and do not use a playback bar. As an important step towards addressing this void, we present the first branched video player with a generalized playback bar that visualizes the tree-like video structure and the buffer levels of the different branches. The player is implemented in dash.js and is made public with this publication, is the first of its kind, and allows both the playback bar and the presentation of branch choices to be customized with regards to visual appearance, functionality, and the content itself. Furthermore, the design is generic (making it applicable to any video) and allows content creators to easily create large numbers of branched movies using a simple metafile format. Finally, and most importantly, we perform a three-phase user study in which we evaluate the playback bar, compare with alternative designs, and other branch-related features. The user study highlights the value of a branched video playback bar, and provides interesting insights into how it and other design customization features may best be integrated into a player.
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| 2. |
- Wrang, Linus, et al.
(author)
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Comparative Analysis of Environmental Contour Approaches to Estimating Extreme Waves for Offshore Installations for the Baltic Sea and the North Sea
- 2021
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In: Journal of Marine Science and Engineering. - : MDPI. - 2077-1312. ; 9:1
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Journal article (peer-reviewed)abstract
- At the stage of design load analysis for offshore installations such as wave energy systems, a critical step is the determination of environmental cases to be evaluated for the definition of the characteristic design load. A commonly used methodology for load case selection, applied in multiple studies and recommended by technical specifications and guidelines, is the environmental contour approach. Here, 50-year environmental contours were generated for four study sites located in the North Sea, Skagerrak and the Baltic Sea by considering both observations and hindcast (model) data. For the construction of the contours, the well-established inverse first-order method (I-FORM) and a modified version using principal component analysis (PCA) were both examined. Furthermore, a 2-dimensional peaks-over-threshold (2D POT) method was evaluated. It was found that a version of the regular I-FORM was able to produce satisfactory contours which properly accounted for the highest waves. When using PCA, the dependency in the data was not properly captured by the probability functions under consideration. The 2D POT method, where applicable, was found to underestimate the extreme sea states. Comparisons between contours obtained from observations and hindcast data showed that the contours may differ substantially depending on the site and method, and thus care must be exercised when using hindcast data for such purposes.
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