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Item A Study on Natural 3D Shape Manipulation in VR(The Eurographics Association, 2018) Cordeiro, E.; Giannini, F.; Monti, M.; Mendes, D.; Ferreira, A.; Livesu, Marco and Pintore, Gianni and Signoroni, AlbertoCurrent immersive modeling environments use non-natural tools and interfaces to support traditional shape manipulation operations. In the future, we expect the availability of natural methods of interaction with 3D models in immersive environments to become increasingly important in several industrial applications. In this paper, we present a study conducted on a group of potential users with the aim of verifying if there is a common strategy in gestural and vocal interaction in immersive environments when the objective is modifying a 3D shape model. The results indicate that users adopt different strategies to perform the different tasks but in the execution of a specific activity it is possible to identify a set of similar and recurrent gestures. In general, the gestures made are physically plausible. During the experiment, the vocal interaction was used quite rarely and never to express a command to the system but rather to better specify what the user was doing with gestures.Item Error Correction in Redirection: Rotational Manipulation for Natural Walking and Control of Walking Paths(The Eurographics Association, 2018) Mizutani, Junya; Matsumoto, Keigo; Nagao, Ryohei; Narumi, Takuji; Tanikawa, Tomohiro; Hirose, Michitaka; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, SueThis study proposes a novel rotational manipulation method for redirection when users attempt to turn around a corner within a virtual environment. The basic manipulation of conventional redirection can be classified into translational, rotational, and curvature manipulations. In conventional rotational manipulation, users must stop and rotate. However, this behavior is not natural in everyday walking. In addition, because the manipulated rotation varies depending on the amount of the user's rotation, this manipulated rotation could differ from the assumed rotation if the user does not rotate by the assumed angle during this manipulation. Correspondingly, the actual walking path may deviate from the planned path. Misalignment of the walking path may cause a deviation in the interaction with an object in real space, thus resulting in collision with real-space objects and other users. We devised a basic manipulation of redirection and formulated a novel method for manipulating the amount of rotation when users rotate while moving. Using this method, we changed the axis of rotational manipulation for preventing mismatches between real and virtual environments, and set an area to correct the error in rotational manipulation. The results of our experiments demonstrated that it is possible to control the walking paths and manipulate the amount of rotation during movement without changing the amount of rotation perceived by users, and without increasing discomfort. The results demonstrated that our method is useful for manipulating the viewpoint when a user walks naturally.Item Visualizing Transport and Mixing in Particle-based Fluid Flows(The Eurographics Association, 2019) Rapp, Tobias; Dachsbacher, Carsten; Schulz, Hans-Jörg and Teschner, Matthias and Wimmer, MichaelTo gain insight into large, time-dependent particle-based fluid flows, we visually analyze Lagrangian coherent structures (LCS), a robust skeleton of the underlying particle dynamics. To identify these coherent structures, we build on recent work that efficiently computes the finite-time Lyapunov exponent (FTLE) directly on particle data. We formulate the LCS definitions for particles based on robust approximations for higher-order derivatives of the FTLE. Based on these formulations, we derive a per-particle distance to the closest coherent structure. This allows us to visually analyze and explore the Lagrangian transport behavior directly on the particle data. We show that this is especially beneficial to detect and visualize flow features on different time scales. Lastly, we apply our approach to study mixing in multiphase flows by visualizing the different types of fluids and their relation to the coherent structures.Item A Gaze-depth Estimation Technique with an Implicit and Continuous Data Acquisition for OST-HMDs(The Eurographics Association, 2017) Lee, Youngho; Piumsomboon, Thammathip; Ens, Barrett; Lee, Gun A.; Dey, Arindam; Billinghurst, Mark; Tony Huang and Arindam DeyThe rapid development of machine learning algorithms can be leveraged for potential software solutions in many domains including techniques for depth estimation of human eye gaze. In this paper, we propose an implicit and continuous data acquisition method for 3D gaze depth estimation for an optical see-Through head mounted display (OST-HMD) equipped with an eye tracker. Our method constantly monitoring and generating user gaze data for training our machine learning algorithm. The gaze data acquired through the eye-tracker include the inter-pupillary distance (IPD) and the gaze distance to the real and virtual target for each eye.Item DimSUM: Dimension and Scale Unifying Map for Visual Abstraction of DNA Origami Structures(The Eurographics Association and John Wiley & Sons Ltd., 2018) Miao, Haichao; Llano, Elisa De; Isenberg, Tobias; Gröller, Eduard; Barišic, Ivan; Viola, Ivan; Jeffrey Heer and Heike Leitte and Timo RopinskiWe present a novel visualization concept for DNA origami structures that integrates a multitude of representations into a Dimension and Scale Unifying Map (DimSUM). This novel abstraction map provides means to analyze, smoothly transition between, and interact with many visual representations of the DNA origami structures in an effective way that was not possible before. DNA origami structures are nanoscale objects, which are challenging to model in silico. In our holistic approach we seamlessly combine three-dimensional realistic shape models, two-dimensional diagrammatic representations, and ordered alignments in one-dimensional arrangements, with semantic transitions across many scales. To navigate through this large, two-dimensional abstraction map we highlight locations that users frequently visit for certain tasks and datasets. Particularly interesting viewpoints can be explicitly saved to optimize the workflow. We have developed DimSUM together with domain scientists specialized in DNA nanotechnology. In the paper we discuss our design decisions for both the visualization and the interaction techniques. We demonstrate two practical use cases in which our approach increases the specialists' understanding and improves their effectiveness in the analysis. Finally, we discuss the implications of our concept for the use of controlled abstraction in visualization in general.Item VR Video Storytelling for Intangible Cultural Heritage Preservation(The Eurographics Association, 2018) Selmanovic, Elmedin; Rizvic, Selma; Harvey, Carlo; Boskovic, Dusanka; Hulusic, Vedad; Chahin, Malek; Sljivo, Sanda; Sablatnig, Robert and Wimmer, MichaelInteractive digital storytelling has become a popular method for virtual cultural heritage presentations. Combinations of stories and 3D virtual reconstructions are attractive for the audience and have high edutainment values. In this paper we investigate if 360 degrees VR videos further contribute to user immersion in the preservation of intangible cultural heritage. It describes a case study of the Mostar bridge diving project, aimed to present and preserve the bridge diving tradition from the Old Bridge in Mostar, Bosnia and Herzegovina. It is a virtual reality application which enables the user to virtually jump off the bridge after watching 360 degrees video stories about its history and the bridge diving tradition and upon successfully completing the quiz evaluation of the knowledge gained from the stories. The user experience evaluation study shows that our method was successful in preserving a form of intangible heritage and posits suggestions that can be used in developing an intangible heritage preservation framework.Item A Visual Interface for Feature Subset Selection Using Machine Learning Methods(The Eurographics Association, 2018) Rojo, Diego; Raya, Laura; Rubio-Sánchez, Manuel; Sánchez, Alberto; García-Fernández, Ignacio and Ureña, CarlosVisual representation of information remains a key part of exploratory data analysis. This is due to the high number of features in datasets and their increasing complexity, together with users' ability to visually understand information. One of the most common operations in exploratory data analysis is the selection of relevant features in the available data. In multidimensional scenarios, this task is often done with the help of automatic dimensionality reduction algorithms from the machine learning field. In this paper we develop a visual interface where users are integrated into the feature selection process of several machine learning algorithms. Users can work interactively with the algorithms in order to explore the data, compare the results and make the appropriate decisions about the feature selection process.Item Visual Analysis of Probabilistic Infection Contagion in Hospitals(The Eurographics Association, 2019) Wunderlich, Marcel; Block, Isabelle; von Landesberger, Tatiana; Petzold, Markus; Marschollek, Michael; Scheithauer, Simone; Schulz, Hans-Jörg and Teschner, Matthias and Wimmer, MichaelClinicians and hygienists need to know how an infection of one patient could be transmitted among other patients in the hospital (e.g., to prevent outbreaks). They need to analyze how many and which patients will possibly be infected, how fast the infection could spread, and which contacts are likely to transfer the infections within the hospital. Currently, infection contagion is modeled and visualized for populations only on an aggregate level, without identification and exploration of possible infection between individuals. We present a novel visual analytics approach that simulates the contagion in a contact graph of patients in a hospital. We propose a clustering approach to identify probable contagion scenarios in the simulation ensemble. Furthermore, our novel visual design for detailed assessment of transmission shows the temporal development of contagion per patient in one view. We demonstrate the capability of our approach to a real-world use case in a German hospital.Item VisualFlatter - Visual Analysis of Distortions in the Projection of Biomedical Structures(The Eurographics Association, 2018) Grossmann, Nicolas; Köppel, Thomas; Gröller, Eduard; Raidou, Renata Georgia; Puig Puig, Anna and Schultz, Thomas and Vilanova, Anna and Hotz, Ingrid and Kozlikova, Barbora and Vázquez, Pere-PauProjections of complex anatomical or biological structures from 3D to 2D are often used by visualization and domain experts to facilitate inspection and understanding. Representing complex structures, such as organs or molecules, in a simpler 2D way often requires less interaction, while enabling comparability. However, the most commonly employed projection methods introduce size or shape distortions, in the resulting 2D representations. While simple projections display known distortion patterns, more complex projection algorithms are not easily predictable.We propose the VisualFlatter, a visual analysis tool that enables visualization and domain experts to explore and analyze projection-induced distortions, in a structured way. Our tool provides a way to identify projected regions with semantically relevant distortions and allows users to comparatively analyze distortion outcomes, either from alternative projection methods or due to different setups through the projection pipeline. The user is given the ability to improve the initial projection configuration, after comparing different setups. We demonstrate the functionality of our tool using four scenarios of 3D to 2D projections, conducted with the help of domain or visualization experts working on different application fields. We also performed a wider evaluation with 13 participants, familiar with projections, to assess the usability and functionality of the Visual Flatter.Item Visual Exploratory Analysis for Multiple T-Maze Studies(The Eurographics Association, 2018) Bechtold, Fabrizia; Splechtna, Rainer; Matkovic, Kresimir; Puig Puig, Anna and Schultz, Thomas and Vilanova, Anna and Hotz, Ingrid and Kozlikova, Barbora and Vázquez, Pere-PauEvaluation of spatial learning and memory in rodents is commonly carried out using different maze settings such as the Multiple T-Maze. State-of-the-art analysis is primarily based on statistics of quantitative measures stemming from animal trajectories in a maze, e.g. path length or correct decisions made. Currently trajectories themselves are analyzed and evaluated one at a time and comparison of multiple trajectories is a tedious task. The resulting findings may not fully answer complex questions that behavioral researchers encounter as well, e.g., why do animals behave in a certain way or can atypical behaviour be detected? This paper describes an innovative approach on how exploratory analysis for Multiple T-Maze studies can be enhanced through interactive visual analysis. We explain our solution for analyzing a whole ensemble of data at once and support the finding of orientational characteristics and migration patterns within the ensemble. We also abstract the analysis tasks for Multiple TMaze studies and, based on these tasks, we extend a coordinated multiple views system to support the solving of fundamental problems which behavioral researchers face. Besides views of standard charts we deploy a multi-resolution heat map and the Gate-O-Gon, which is a novel visual element. It gives clues on the animals' general movement orientation and distribution of revisited gates, as well as enhances the discovery of patterns in movement and identifying of irregular behavior. Finally we demonstrate the usefulness of the newly proposed approach using a real life data set consisting of 400 Multiple T-Maze runs.