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Item Rendering and Extracting Extremal Features in 3D Fields(The Eurographics Association and John Wiley & Sons Ltd., 2018) Kindlmann, Gordon L.; Chiw, Charisee; Huynh, Tri; Gyulassy, Attila; Reppy, John; Bremer, Peer-Timo; Jeffrey Heer and Heike Leitte and Timo RopinskiVisualizing and extracting three-dimensional features is important for many computational science applications, each with their own feature definitions and data types. While some are simple to state and implement (e.g. isosurfaces), others require more complicated mathematics (e.g. multiple derivatives, curvature, eigenvectors, etc.). Correctly implementing mathematical definitions is difficult, so experimenting with new features requires substantial investments. Furthermore, traditional interpolants rarely support the necessary derivatives, and approximations can reduce numerical stability. Our new approach directly translates mathematical notation into practical visualization and feature extraction, with minimal mental and implementation overhead. Using a mathematically expressive domain-specific language, Diderot, we compute direct volume renderings and particlebased feature samplings for a range of mathematical features. Non-expert users can experiment with feature definitions without any exposure to meshes, interpolants, derivative computation, etc. We demonstrate high-quality results on notoriously difficult features, such as ridges and vortex cores, using working code simple enough to be presented in its entirety.Item Algorithmic Improvements on Hilbert and Moore Treemaps for Visualization of Large Tree-structured Datasets(The Eurographics Association, 2021) Scheibel, Willy; Weyand, Christopher; Bethge, Joseph; Döllner, Jürgen; Agus, Marco and Garth, Christoph and Kerren, AndreasHilbert and Moore treemaps are based on the same named space-filling curves to lay out tree-structured data for visualization. One main component of them is a partitioning subroutine, whose algorithmic complexity poses problems when scaling to industry-sized datasets. Further, the subroutine allows for different optimization criteria that result in different layout decisions. This paper proposes conceptual and algorithmic improvements to this partitioning subroutine. Two measures for the quality of partitioning are proposed, resulting in the min-max and min-variance optimization tasks. For both tasks, linear-time algorithms are presented that find an optimal solution. The implementation variants are evaluated with respect to layout metrics and run-time performance against a previously available greedy approach. The results show significantly improved run time and no deterioration in layout metrics, suggesting effective use of Hilbert and Moore treemaps for datasets with millions of nodes.Item A context-aware immersive interface for teleoperation of mobile robots(The Eurographics Association, 2020) Quintas, João; Almeida, Luís; Sousa, Elísio; Menezes, Paulo; Dias, Paulo and Menezes, PauloIn this paper we present a context-aware immersive teleoperation interface to assist operators during navigation tasks. This new interface strategy aims to address the problems associated with mental overload, often experienced by operators of teleoperated devices. Our approach simplifies the high complexity of information displayed in control rooms. Our approach includes a context-based human-robot interaction framework that detects relevant information and automatically adapts the displayed interface in virtual windshield. Results showed that the proposed approach enhances user immersion while maximizes task performances and minimizes the operator physical and cognitive workload.Item A Massively Parallel CUDA Algorithm to Compute and Visualize the Solvent Excluded Surface for Dynamic Molecular Data(The Eurographics Association, 2019) Schäfer, Marco; Krone, Michael; Byska, Jan and Krone, Michael and Sommer, BjörnThe interactive visualization of molecular surfaces can help users to understand the dynamic behavior of proteins in molecular dynamics simulations. These simulations play an important role in biochemical and pharmaceutical research, e.g. in drug design. The efficient calculation of molecular surfaces in a fast and memory-saving way is a challenging task. For example, to gain a detailed understanding of complex diseases like Alzheimer, conformational changes and spatial interactions between molecules have to be investigated. Molecular surfaces, such as Solvent Excluded Surfaces (SES), are instrumental for identifying structures such as tunnels or cavities that critically influence transport processes and docking events, which might induce enzymatic reactions. Therefore, we developed a highly parallelized algorithm that exploits the massive computing power of modern graphics hardware. Our analytical algorithm is suitable for the real-time computation of dynamic SES based on many time steps, as it runs interactively on a single consumer GPU for more than 20 k atoms.Item On the Beat: Analysing and Evaluating Synchronicity in Dance Performances(The Eurographics Association, 2023) Menzel, Malte; Tauscher, Jan-Philipp; Magnor, Marcus; Guthe, Michael; Grosch, ThorstenThis paper presents a method to analyse and evaluate synchronicity in dance performances automatically. Synchronisation of a dancer's movement and the accompanying music is a vital characteristic of dance performances. We propose a method that fuses computer vision-based extraction of dancers' body pose information and audio beat tracking to examine the alignment of the dance motions with the background music. Specifically, the motion of the dancer is analysed for rhythmic dance movements that are then subsequently correlated to the musical beats of the soundtrack played during the performance. Using a single mobile phone video recording of a dance performance only, our system is easily usable in dance rehearsal contexts. Our method evaluates accuracy for every motion beat of the performance on a timeline giving users detailed insight into their performance. We evaluated the accuracy of our method using a dataset containing 17 video recordings of real world dance performances. Our results closely match assessments by professional dancers, indicating correct analysis by our method.Item Towards Biomechanically and Visually Plausible Volumetric Cutting Simulation of Deformable Bodies(The Eurographics Association, 2019) Qian, Yinling; Huang, Wenbin; Si, Weixin; Liao, Xiangyun; Wang, Qiong; Heng, Pheng-Ann; Lee, Jehee and Theobalt, Christian and Wetzstein, GordonDue to the simplicity and high efficiency, composited finite element method(CFEM) based virtual cutting attracted much attention in the field of virtual surgery in recent years. Even great progress has been made in volumetric cutting of deformable bodies, there are still several open problems restricting its applications in practical surgical simulator. First among them is cutting fracture modelling. Recent methods would produce cutting surface immediately after an intersection between the cutting plane and the object. But in real cutting, biological tissue would first deform under the external force induced by scalpel and then fracture occurs when the stress exceeds a threshold. Secondly, it's computation-intensive to reconstruct cutting surface highly consistent with the scalpel trajectory, since reconstructed cutting surface in CFEM-based virtual cutting simulation is grid-dependent and the accuracy of cutting surface is proportional to the grid resolution. This paper propose a virtual cutting method based on CFEM which can effectively simulate cutting fracture in a biomechanically and visually plausible way and generate cutting surface which is consistent with the scalpel trajectory with a low resolution finite element grid. We model this realistic cutting as a deformation-fracture repeating process. In deformation stage, the object will deform along with the scalpel motion, while in the fracture stage cutting happens and a cutting surface will be generated from the scalpel trajectory. A delayed fracturing criteria is proposed to determine when and how the cutting fracture occurs and an influence domain adaptation method is employed to generate accurate cutting surface in both procedures of deformation and fracture. Experiments show that our method can realistically simulate volumetric cutting of deformable bodies and efficiently generate accurate cutting surface thus facilitating interactive applications.Item Interactions for Seamlessly Coupled Exploration of High-Dimensional Images and Hierarchical Embeddings(The Eurographics Association, 2023) Vieth, Alexander; Lelieveldt, Boudewijn; Eisemann, Elmar; Vilanova, Anna; Höllt, Thomas; Guthe, Michael; Grosch, ThorstenHigh-dimensional images (i.e., with many attributes per pixel) are commonly acquired in many domains, such as geosciences or systems biology. The spatial and attribute information of such data are typically explored separately, e.g., by using coordinated views of an image representation and a low-dimensional embedding of the high-dimensional attribute data. Facing ever growing image data sets, hierarchical dimensionality reduction techniques lend themselves to overcome scalability issues. However, current embedding methods do not provide suitable interactions to reflect image space exploration. Specifically, it is not possible to adjust the level of detail in the embedding hierarchy to reflect changing level of detail in image space stemming from navigation such as zooming and panning. In this paper, we propose such a mapping from image navigation interactions to embedding space adjustments. We show how our mapping applies the "overview first, details-on-demand" characteristic inherent to image exploration in the high-dimensional attribute space. We compare our strategy with regular hierarchical embedding technique interactions and demonstrate the advantages of linking image and embedding interactions through a representative use case.Item Embodied Augmented Reality for Lower Limb Rehabilitation(The Eurographics Association, 2024) Sarri, Froso; Kasnesis, Panagiotis; Symeonidis, Spyridon; Paraskevopoulos, Ioannis Th.; Diplaris, Sotiris; Posteraro, Federico; Georgoudis, George; Mania, Katerina; Pelechano, Nuria; Pettré, JulienImmersive platforms have emerged as valuable tools in rehabilitation, with potential to enhance patient engagement and recovery outcomes. Addressing the limitations of traditional Virtual Reality (VR) setups that restrict physical movement, this paper presents the system architecture of a novel, head-worn, Augmented Reality (AR) system for lower limb rehabilitation. The rehabilitation experience is enhanced by embodying avatars that replicate patients' movements. The system integrates varied avatar perspectives, such as mirror and follow modes, based on an avatar centered interface. The proposed system architecture supports seated and standing exercises, expanding the scope of rehabilitation beyond just gait. Computer vision-based 3D pose estimation captures patients' movement, mapped onto the avatar in real-time, accurately estimating the co-ordinates of 3D body landmarks. Wearable sensors evaluate patients' movements by utilizing deep learning to discern movement patterns. Feedback to patients is provided based on visual cues indicating limb areas for exercise adjustment so that exercise execution is improved. Embodiment has the potential to improve exercise understanding and assists patients' rehabilitation recovery.Item User Interaction Feedback in a Hand-Controlled Interface for Robot Team Tele-operation Using Wearable Augmented Reality(The Eurographics Association, 2017) Cannavò, Alberto; Lamberti, Fabrizio; Andrea Giachetti and Paolo Pingi and Filippo StancoContinuous advancements in the field of robotics and its increasing spread across heterogeneous application scenarios make the development of ever more effective user interfaces for human-robot interaction (HRI) an extremely relevant research topic. In particular, Natural User Interfaces (NUIs), e.g., based on hand and body gestures, proved to be an interesting technology to be exploited for designing intuitive interaction paradigms in the field of HRI. However, the more sophisticated the HRI interfaces become, the more important is to provide users with an accurate feedback about the state of the robot as well as of the interface itself. In this work, an Augmented Reality (AR)-based interface is deployed on a head-mounted display to enable tele-operation of a remote robot team using hand movements and gestures. A user study is performed to assess the advantages of wearable AR compared to desktop-based AR in the execution of specific tasks.Item Study of the Influence of User Characteristics on the Virtual Reality Presence(The Eurographics Association, 2018) Mayor, Jesús; Sánchez, Alberto; Raya, Laura; García-Fernández, Ignacio and Ureña, CarlosIn recent years, virtual reality has grown a lot in different areas of application, including ludic, social and research, being used by a large and growing number of users with different profiles. Presence is one of the most distinctive and important features of a virtual reality experience. The aim of this article is to study the most suitable areas of application for users and to analyze the influence of different characteristics of the user's profile in the perceived presence. We have tested the interest applications indicated by 159 subjects and we have designed an immersive virtual reality experience, testing the behavior and performance of 48 users. The results obtained show that gender can influence the perceptual sensation of presence in these types of virtual environments.