Browsing by Author "Mania, Katerina"

Now showing 1 - 6 of 6
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    Audio Augmented Reality for Cultural Heritage Outdoors
    (The Eurographics Association, 2022) Kritikos, Yannis; Giariskanis, Fotios; Protopapadaki, Eftychia; Papanastasiou, Anthi; Papadopoulou, Eleni; Mania, Katerina; Ponchio, Federico; Pintus, Ruggero
    Audio Augmented Reality (AAR) is a novel area of AR representing the augmentation of reality with auditory input. The way auditory input is combined with 3D superimposed information in AAR is challenging, especially in noisy and busy environments outdoors. This paper presents a novel, work-in-progress, mobile AAR experience that is deployed in a city environment while walking past seven archaeological excavation sites in the city of Chania, Crete, Greece. The proposed AAR experience embeds 3D graphics and audio related to the cultural content while a visitor walks around the city, offering a non-linear narrative. Visual and audio digital elements are accurately geo-located while a personalized AAR SoundScape Generator boosts audience creativity. AAR design is optimized for outdoor use.
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    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, Julien
    Immersive 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.
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    EUROGRAPHICS 2024: Tutorials Frontmatter
    (Eurographics Association, 2024) Mania, Katerina; Artusi, Alessandro; Mania, Katerina; Artusi, Alessandro
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    An Inverted Pyramid Acceleration Structure Guiding Foveated Sphere Tracing for Implicit Surfaces in VR
    (The Eurographics Association, 2023) Polychronakis, Andreas; Koulieris, George Alex; Mania, Katerina; Ritschel, Tobias; Weidlich, Andrea
    In this paper, we propose a novel rendering pipeline for sphere tracing signed distance functions (SDFs) that significantly improves sphere tracing performance. Previous methods simply focus on over-relaxing the step size by a fixed amount and thus reducing the total step count of the ray based on the error of the previous step at the full rendering resolution. Unlike those, our system reconstructs the final image in a multi-scale inverted pyramid fashion that provides progressively finer approximations of a surface's distance from the camera origin. We initiate sphere tracing at a very low resolution approximation of the scene which provides an initial estimate of the closest surface to a group of rays to be sphere traced. We shoot and trace those rays from that approximated distance instead of shooting them from the camera origin, providing a massive head-start for the rays to leap ahead in the 3D scene, successively generating the following level until the full resolution is reached. This significantly reduces the total step count. Moving up in the pyramid in higher and higher resolutions we repeat this process to further eliminate sphere tracing steps. The multiple resolution levels of the pyramid ascertain that we avoid jumps of the ray in the 3D scene that would potentially generate artefacts, especially around scene edges that might be missed when rendering at lower resolutions. This approach allows for a much more efficient use of computational resources and results in a significant boost in performance (more than 20x speed-up in some cases). Integrating a foveated rendering algorithm within the inverted pyramid pipeline further accelerates performance enabling 16x super-sample anti-aliasing of implicit surfaces in a VR headset. Our experiments demonstrate that our image manipulation remains imperceptible. Our benchmark evaluation indicated a significant boost in sphere tracing performance with or without foveated rendering applied. This enables efficiently rendering SDFs in VR headsets, often otherwise impossible due to limited performance.
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    Near-Eye Display and Tracking Technologies for Virtual and Augmented Reality
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) Koulieris, George; AKSIT, KAAN; Stengel, Michael; Mantiuk, Rafał K.; Mania, Katerina; Richardt, Christian; Giachetti, Andrea and Rushmeyer, Holly
    Virtual and augmented reality (VR/AR) are expected to revolutionise entertainment, healthcare, communication and the manufacturing industries among many others. Near-eye displays are an enabling vessel for VR/AR applications, which have to tackle many challenges related to ergonomics, comfort, visual quality and natural interaction. These challenges are related to the core elements of these near-eye display hardware and tracking technologies. In this state-of-the-art report, we investigate the background theory of perception and vision as well as the latest advancements in display engineering and tracking technologies. We begin our discussion by describing the basics of light and image formation. Later, we recount principles of visual perception by relating to the human visual system. We provide two structured overviews on state-of-the-art near-eye display and tracking technologies involved in such near-eye displays. We conclude by outlining unresolved research questions to inspire the next generation of researchers.
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    Skipping Spheres: SDF Scaling & Early Ray Termination for Fast Sphere Tracing
    (The Eurographics Association, 2024) Polychronakis, Andreas; Koulieris, George Alex; Mania, Katerina; Hunter, David; Slingsby, Aidan
    This paper presents a rapid rendering pipeline for sphere tracing Signed Distance Functions (SDFs), showcasing a notable boost in performance compared to the current state-of-the-art. Existing methods endeavor to reduce the ray step count by adjusting step size using heuristics or by rendering multiple intermediate lower-resolution buffers to pre-calculate non-salient pixels at reduced quality. However, the accelerated performance with low-resolution buffers often introduces artifacts compared to fully sphere-traced scenes, especially for smaller features, which might go unnoticed altogether. Our approach significantly reduces steps compared to prior work while minimising artifacts. We accomplish this based on two key observations and by employing a single low-resolution buffer: Firstly, we perform SDF scaling in the low-resolution buffer, effectively enlarging the footprint of the implicit surfaces when rendered in low resolution, ensuring visibility of all SDFs. Secondly, leveraging the low-resolution buffer rendering, we detect when a ray converges to high-cost surface edges and can terminate sphere tracing earlier than usual, further reducing step count. Our method achieves a substantial performance improvement (exceeding 3× in certain scenes) compared to previous approaches, while minimizing artifacts, as demonstrated in our visual fidelity evaluation.