Visual Distortions in 360-degree Videos.

Omnidirectional (or 360°) images and videos are emergent signals being used in many areas, such as robotics and virtual/augmented reality. In particular, for virtual reality applications, they allow an immersive experience in which the user can interactively navigate through a scene with three degrees of freedom, wearing a head-mounted display. Current approaches for capturing, processing, delivering, and displaying 360° content, however, present many open technical challenges and introduce several types of distortions in the visual signal. Some of the distortions are specific to the nature of 360° images and often differ from those encountered in classical visual communication frameworks. This paper provides a first comprehensive review of the most common visual distortions that alter 360° signals going through the different processing elements of the visual communication pipeline. While their impact on viewers' visual perception and the immersive experience at large is still unknown-thus, it is an open research topic-this review serves the purpose of proposing a taxonomy of the visual distortions that can be encountered in 360° signals. Their underlying causes in the end-to-end 360° content distribution pipeline are identified. This taxonomy is essential as a basis for comparing different processing techniques, such as visual enhancement, encoding, and streaming strategies, and allowing the effective design of new algorithms and applications. It is also a useful resource for the design of psycho-visual studies aiming to characterize human perception of 360° content in interactive and immersive applications

Visual Distortions in 360-degree Videos

Omnidirectional (or 360-degree) images and videos are emergent signals in many areas such as robotics and virtual/augmented reality. In particular, for virtual reality, they allow an immersive experience in which the user is provided with a 360-degree field of view and can navigate throughout a scene, e.g., through the use of Head Mounted Displays. Since it represents the full 360-degree field of view from one point of the scene, omnidirectional content is naturally represented as spherical visual signals. Current approaches for capturing, processing, delivering, and displaying 360-degree content, however, present many open technical challenges and introduce several types of distortions in these visual signals. Some of the distortions are specific to the nature of 360-degree images, and often different from those encountered in the classical image communication framework. This paper provides a first comprehensive review of the most common visual distortions that alter 360-degree signals undergoing state of the art processing in common applications. While their impact on viewers' visual perception and on the immersive experience at large is still unknown ---thus, it stays an open research topic--- this review serves the purpose of identifying the main causes of visual distortions in the end-to-end 360-degree content distribution pipeline. It is essential as a basis for benchmarking different processing techniques, allowing the effective design of new algorithms and applications. It is also necessary to the deployment of proper psychovisual studies to characterise the human perception of these new images in interactive and immersive applications

Realtà Virtuale: stato dell'arte e studio sperimentale di tracce di traffico dati

Questo elaborato presenta nella sua parte iniziale un'esplorazione della storia e della tecnologia della realtà virtuale in modo da poter meglio inquadrare l'analisi del traffico generato da applicazioni di Realtà Virtuale (VR). Tale analisi si basa su una serie di misure di traffico di un visore VR Meta Quest 2, e riguarda il traffico totale scambiato sul cavo USB usato per collegare il visore a un computer, il traffico nelle due direzioni (ovvero, da e verso il visore), la lunghezza dei pacchetti, e il tempo interpacchetto. Si daranno delle spiegazione ai risultati ottenuti sulla base delle tracce di traffico reali. Un passo successivo a questo elaborato sarà quello di formalizzare i risultati in un modello matematico che poi potrà essere usato come base per sviluppare algoritmi di compressione dati predittivi. Tutto ciò risulta molto importante visto l'importante sviluppo e diffusione che questa tecnologia sta avendo

Remote surgery guidance using virtual reality and 360º video

There is a strong demand for the use of virtual reality (VR) in healthcare, particularly in surgical procedures. This thesis motivates this need and presents the design and prototype implementation of Virtual Reality Remote Surgery Guidance (VRSG). This tool allows the live connection of a remote specialist surgeon to provide live guidance on surgeries at remote locations, particularly in low-and-middle-income countries (LMICs). VRSG also supports an educational experience by offering the ability for users to follow recorded surgeries for practice and review purposes. The main contributions of this work are the feasibility demonstration of the proposed VRSG system through a rigorous 3D user interface design process, the implementation of a prototype VR application that realizes the proposed design, and the usability evaluation that offers evidence towards the effectiveness of the proposed tool. VRSG’s design and implementation can be summarized as follows. The design of an interactive, immersive interface of the remote surgeon connected to the surgery room via an immersive 360º video stream mounted in a strategic location inside the surgery room. Two additional non-immersive streams were added to the interface to show a detailed view of the surgery site and monitor with patient’s vital signs. The remote surgeon offers guidance to the local surgery team by performing annotations directly onto the detailed views, which are transmitted to the surgery room. To simulate the surgery room interface, we created a desktop application that displays the remote surgeon's audio, current point of view, and annotations. All the streaming videos can be saved on the local server in support of the educational element of VRSG. We performed a usability evaluation of VRSG with 6 participants to test the efficiency of the remote surgeon’s user interface. Descriptive statistics show that participants had an overall positive experience with the tool, and qualitative observations pointed to limitations that we discuss and address as recommendations for the evolution of the VRSG. Overall, this thesis achieved its goals through the design, implementation, and usability assessment of a tool to facilitate remote surgery guidance by experts

"Enriching 360-degree technologies through human-computer interaction: psychometric validation of two memory tasks"

This doctoral dissertation explores the domain of neuropsychological assessment, with the objective of gaining a comprehensive understanding of an individual's cognitive functioning and detecting possible impairments. Traditional assessment tools, while possessing inherent value, frequently exhibit a deficiency in ecological validity when evaluating memory, as they predominantly concentrate on short-term, regulated tasks. To overcome this constraint, immersive technologies, specifically virtual reality and 360° videos, have surfaced as promising instruments for augmenting the ecological validity of cognitive assessments. This work examines the potential advantages of immersive technologies, particularly 360° videos, in enhancing memory evaluation. First, a comprehensive overview of contemporary virtual reality tools employed in the assessment of memory, as well as their convergence with conventional assessment measures has been provided. Then, the present study utilizes cluster and network analysis techniques to categorize 360° videos according to their content and applications, thereby offering significant insights into the potential of this nascent medium. The study introduces then a novel platform, Mindscape, that aims to address the existing technological disparity, thereby enhancing the accessibility of clinicians and researchers in developing cognitive tasks within immersive environments. The conclusion of the thesis encompasses the psychometric validation of two memory tasks, which have been specifically developed with Mindscape to assess episodic and spatial memory. The findings demonstrate disparities in cognitive performance between individuals diagnosed with Mild Cognitive Impairment and those without cognitive impairments, underscoring the interrelated nature of cognitive processes and the promising prospects of virtual reality technology in improving the authenticity of real-world experiences. Overall, this dissertation aims to respond to the demand for practical and ecologically valid neuropsychological assessments within the dynamic field of neuropsychology. It achieves this by integrating user-friendly platforms and immersive cognitive tasks into its methodology. By highlighting a shift in the field of neuropsychology towards prioritizing functional and practical assessments over theoretical frameworks, this work indicates a changing perspective within the discipline. This study highlights the potential of comprehensive and purpose-oriented assessment methods in cognitive evaluations, emphasizing the ongoing significance of research in fully comprehending the capabilities of immersive technologies