Objective Evaluation Criteria for Shooting Quality of Stereo Cameras over Short Distance

Stereo cameras are the basic tools used to obtain stereoscopic image pairs, which can lead to truly great image quality. However, some inappropriate shooting conditions may cause discomfort while viewing stereo images. It is therefore considerably necessary to establish the perceptual criteria that can be used to evaluate the shooting quality of stereo cameras. This article proposes objective quality evaluation criteria based on the characteristics of parallel and toed-in camera configurations. Considering the different internal structures and basic shooting principles, this paper focuses on short-distance shooting conditions and establishes assessment criteria for both parallel and toed-in camera configurations. Experimental results show that the proposed evaluation criteria can predict the visual perception of stereoscopic images and effectively evaluate stereoscopic image quality

Remote Visual Observation of Real Places Through Virtual Reality Headsets

Virtual Reality has always represented a fascinating yet powerful opportunity that has attracted studies and technology developments, especially since the latest release on the market of powerful high-resolution and wide field-of-view VR headsets. While the great potential of such VR systems is common and accepted knowledge, issues remain related to how to design systems and setups capable of fully exploiting the latest hardware advances. The aim of the proposed research is to study and understand how to increase the perceived level of realism and sense of presence when remotely observing real places through VR headset displays. Hence, to produce a set of guidelines that give directions to system designers about how to optimize the display-camera setup to enhance performance, focusing on remote visual observation of real places. The outcome of this investigation represents unique knowledge that is believed to be very beneficial for better VR headset designs towards improved remote observation systems. To achieve the proposed goal, this thesis presents a thorough investigation of existing literature and previous researches, which is carried out systematically to identify the most important factors ruling realism, depth perception, comfort, and sense of presence in VR headset observation. Once identified, these factors are further discussed and assessed through a series of experiments and usability studies, based on a predefined set of research questions. More specifically, the role of familiarity with the observed place, the role of the environment characteristics shown to the viewer, and the role of the display used for the remote observation of the virtual environment are further investigated. To gain more insights, two usability studies are proposed with the aim of defining guidelines and best practices. The main outcomes from the two studies demonstrate that test users can experience an enhanced realistic observation when natural features, higher resolution displays, natural illumination, and high image contrast are used in Mobile VR. In terms of comfort, simple scene layouts and relaxing environments are considered ideal to reduce visual fatigue and eye strain. Furthermore, sense of presence increases when observed environments induce strong emotions, and depth perception improves in VR when several monocular cues such as lights and shadows are combined with binocular depth cues. Based on these results, this investigation then presents a focused evaluation on the outcomes and introduces an innovative eye-adapted High Dynamic Range (HDR) approach, which the author believes to be of great improvement in the context of remote observation when combined with eye-tracked VR headsets. Within this purpose, a third user study is proposed to compare static HDR and eye-adapted HDR observation in VR, to assess that the latter can improve realism, depth perception, sense of presence, and in certain cases even comfort. Results from this last study confirmed the author expectations, proving that eye-adapted HDR and eye tracking should be used to achieve best visual performances for remote observation in modern VR systems

Objective evaluation criteria for stereo camera shooting quality under different shooting parameters and shooting distances

The vigorous development of 3D technology has improved the photography technology of stereo cameras constantly. However, there are no widely recognized objective evaluation criteria for stereo camera shooting quality under different shooting parameters and shooting distances. At the same time, no shooting guideline can be used for reference when people take stereoscopic images. To solve this problem, we propose the objective evaluation criteria of shooting quality of two types of stereo cameras (parallel and toed-in camera configurations) under three shooting conditions (macro shooting, short, and long distance shooting). In our work, several prominent evaluation factors are built by analyzing the characteristics of each shooting condition. Based on the effective five-point scale used in our subjective experiments, the relationships between shooting factors and shooting quality are obtained and then effectively integrated together to build the overall evaluation criteria. Finally, extensive experiments have been conducted, and the results demonstrate that the proposed approach can effectively evaluate the shooting quality of stereo cameras

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 341)

This bibliography lists 133 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during September 1990. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

Biosignalų požymių regos diskomfortui vertinti išskyrimas ir tyrimas

Comfortable stereoscopic perception continues to be an essential area of research. The growing interest in virtual reality content and increasing market for head-mounted displays (HMDs) still cause issues of balancing depth perception and comfortable viewing. Stereoscopic views are stimulating binocular cues – one type of several available human visual depth cues which becomes conflicting cues when stereoscopic displays are used. Depth perception by binocular cues is based on matching of image features from one retina with corresponding features from the second retina. It is known that our eyes can tolerate small amounts of retinal defocus, which is also known as Depth of Focus. When magnitudes are larger, a problem of visual discomfort arises. The research object of the doctoral dissertation is a visual discomfort level. This work aimed at the objective evaluation of visual discomfort, based on physiological signals. Different levels of disparity and the number of details in stereoscopic views in some cases make it difficult to find the focus point for comfortable depth perception quickly. During this investigation, a tendency for differences in single sensor-based electroencephalographic EEG signal activity at specific frequencies was found. Additionally, changes in eye tracker collected gaze signals were also found. A dataset of EEG and gaze signal records from 28 control subjects was collected and used for further evaluation. The dissertation consists of an introduction, three chapters and general conclusions. The first chapter reveals the fundamental knowledge ways of measuring visual discomfort based on objective and subjective methods. In the second chapter theoretical research results are presented. This research was aimed to investigate methods which use physiological signals to detect changes on the level of sense of presence. Results of the experimental research are presented in the third chapter. This research aimed to find differences in collected physiological signals when a level of visual discomfort changes. An experiment with 28 control subjects was conducted to collect these signals. The results of the thesis were published in six scientific publications – three in peer-reviewed scientific papers, three in conference proceedings. Additionally, the results of the research were presented in 8 conferences.Dissertatio

Dynamism in the context of views out: A literature review

Previous studies have shown that access to a satisfactory view to the outside with sufficient daylight is essential for building occupants\u27 health and well-being. It has also been suggested that certain features of visual content improve view-out quality, such as horizontal stratification, natural landscapes, distant features, and diversity of visual elements. Additionally, having movement and changes in viewing content has been shown to further strengthen building occupants’ engagement and connectivity to their surrounding environment. The objective of this paper is to review the literature on the dynamism of the view content and the inclusion of this criterion in the current metrics of view evaluation. Our review revealed a need for further research on view dynamism, especially focusing on testing different types, speeds, and scales of movement on view quality assessment. It also showed that more comprehensive view evaluation frameworks should be developed to accurately preserve the dynamic qualities of window views in experimental settings. While many view rating metrics have acknowledged the importance of movement, this criterion is to date ignored or only poorly included in existing metrics, which further highlights the need of learning more about this topic

Application of intraoperative quality assurance to laparoscopic total mesorectal excision surgery

Introduction: The role of laparoscopy in the surgical management of rectal cancer is debated. Randomised trials have reported contrasting results with inadequate specimens obtained in a minority of patients. The reasons behind these findings are unclear. Complex surgical interventions and human performance are prone to variation, which may account for outcome differences, but neither are robustly measured. Application of quality assurance (QA) to the intraoperative period could explore surgical performance and any relationship with subsequent outcomes. The overarching aim of this thesis is the promotion of oncological and patient safety through application of QA to laparoscopic TME surgery. Methods: Evidence synthesis of QA tools was obtained through a systematic review to identify reported objective laparoscopic total mesorectal excision (TME) assessment tools. Development of novel QA tools for laparoscopic TME was performed and applied and validated using case video from two multicentre randomised trials with reliability and validity of the laparoscopic TME performance tool (L-TMEpt) assessed. A multicentre randomised trial comparing 3D vs. 2D laparoscopic TME was performed incorporating objective performance analyses. Scores divided surgeons into quartiles and compared with histopathological and clinical endpoints. A novel intraoperative adverse event classification was developed and piloted. Results: 176 cases from 48 credentialed surgeons were analysed. L-TMEpt inter-rater, test-retest and internal consistency reliabilities were established. Substantial variation in surgical performance were seen. Scores were strongly associated with the number of intraoperative errors, plane of mesorectal dissection and short-term patient morbidity. Upper quartile surgeons obtained excellent results compared with the lower quartile (mesorectal fascia 93% vs. 59%, NNT 2.9, p=0.002; 30-day morbidity 23% vs. 48%, NNT 4, p=0.043). Conclusions: Intraoperative QA using assessment tools can objectively and reliably measure complex cancer interventions. Laparoscopic TME surgical performance assessment showed substantial variation which is strongly associated with clinical outcomes holding implications for surgical trial design and interpretation.Open Acces

Photorealistic True-Dimensional Visualization of Remote Panoramic Views for VR Headsets

© 2023 IEEE. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/Virtual Reality headsets have evolved to include unprecedented display quality. Meantime, they have become light-weight, wireless and low-cost, which has opened to new applications and a much wider audience. Photo-based omnidirectional imaging has also developed, becoming directly exploitable for VR, with their combination proven suitable for: remote visits and realistic scene reconstruction, operator’s training and control panels, surveillance and e-tourism. There is however a limited amount of scientific work assessing VR experience and user’s performance in photo-based environment representations. This paper focuses on assessing the effect of photographic realism in VR when observing real places through a VR headset, for two different pixel-densities of the display, environment types and familiarity levels. Our comparison relies on the observation of static three-dimensional and omnidirectional photorealistic views of environments. The aim is to gain an insight about how photographic texture can affect perceived realness, sense of presence and provoked emotions, as well as perception of image-lighting and actual space dimension (true-dimension). Two user studies are conducted based on subjective rating and measurements given by users to a number of display and human factors. The display pixel-density affected the perceived image-lighting and prevailed over better lighting specs. The environment illumination and distance to objects generally played a stronger role than display. The environment affected the perceived image-lighting, spatial presence, depth impression and specific emotions. Distances to a set of objects were generally accurately estimated. Place familiarity enhanced perceived realism and presence. They confirmed some previous studies, but also introduced new elements.Peer reviewe

Open Profiling of Quality: A Mixed Methods Research Approach for Audiovisual Quality Evaluations

Den Anforderungen der Konsumenten gerecht zu werden und ihnen eine immer besser werdende Quality of Experience zu bieten, ist eine der großen Herausforderungen jeder Neuentwicklung im Bereich der Multimediasysteme. Doch proportional zur technischen Komplexität neuer Systeme, in denen Komponenten unterschiedlicher Technologien zu neuen System wie zum Beispiel mobilem 3D-Fernsehen verschmolzen werden, steigt auch die Frage, wie eine optimierte Quality of Experience eigentlich zu erreichen ist. Daher werden seit langer Zeit Nutzertests zur subjektiven Qualitätsbewertung durchgeführt. Deren Ziel über den gesamten Entwcklungsprozesses ist es, die kritischen Komponenten des Systems mit so wenig wie möglich wahrnehmbarem Einfluss auf diewahrgenommene Qualität des Nutzers zu optimieren. Bereits seit den 1970er Jahren werden hierfür Leitfäden verschiedener Standardisierungsgremien zur Verfügung gestellt, in denen unterschiedliche Evaluationsmethoden definiert sind, um die wahrgenommene Gesamtqualität des Systems mit Hilfe von Skalen quantitativ evaluieren zu können. Aktuelle Ansätze erweitern diese klassische Methoden um Sichtweise, die über die klassische Evaluation hedonistischer Gesamtqualität hinausgehen, um das Wissen über individuell zugrundeliegende Qualitätsfaktoren zu erweitern.Die vorliegende Dissertation verfolgt dabei zwei Ziele. Zum einen soll eine audiovisuelle Evaluationsmethode entwickelt werden, die eine kombinierte Analyse quantitativer und qualitativer Daten ermöglicht, um eine Verknüpfung hedonistischer Qualität und zugrundeliegender Qualitätsfaktoren zu ermöglichen. Weiter soll diese Methode innerhalb des Gebiets der mobiler 3DTV-Systeme erprobt und validiert werden.Open Profiling of Quality (OPQ) als Evaluationsmethode kombiniert quantitative Evaluation wahrgenommener Gesamtqualität und deskriptive, sensorische Analyse zur Erhebung individueller Qualitätsfaktoren. Die Methode ist für Erhebungen mit naiven Probanden geeignet. OPQ wurde unter besonderer Beachtung von Validität und Reliabilität in einem konstruktivem Ansatz entwickelt und in einer Folge von Studien während der Entwicklung eines mobilem 3DTV-Systems mit über 300 Probanden angewendet. Die Ergebnisse dieser Studien unterstreichen die sich ergänzenden Ergebnisse quantitativer und sensorischer Analysen.Neben der Entwicklung von OPQ werden in der vorliegenden Arbeit weitere Ansätze sensorischer Analyse präsentiert und miteinander verglichen. Gerade dieser Vergleich ist ein wichtiger Bestandteil der Validierung der OPQ-Methode. Um die Stärken und Schwächen jeder Methode ganzheitlich erfassen und vergleichen zu können, wurde hierfür ein Methodenvergleichsmodell entwickelt und operationalisiert, das den methodischen Beitrag der Arbeit vervollständigtTo meet the requirements of consumers and to provide them with a greater quality of experience than existing systems do is a key issue for the success of modern multimedia systems. However, the question about an optimized quality of experience becomes more and more complex as technological systems are evolving and several systems are merged into new ones, e.g. systems for mobile 3D television and video. To be able to optimize critical components of a system under development with as little perceptual errors as possible, user studies are conducted throughout the whole process. A variety of research methods for different purposes have been provided by standardization bodies since the 1970s. These methods allow researchers to evaluate the hedonic excellence of a set of test stimuli. However, a broader view to quality has been taken recently to be able to evaluate quality beyond its hedonic excellence to obtain a greater knowledge about perceived quality and its subjective quality factors that impact on the user.The goal of this thesis is twofold. The primary goal is the development of a validated mixed methods research approach for audiovisual quality evaluations. The method shall allow collecting quantitative and descriptive data during the experiment to combine evaluation of hedonic excellence and the elicitation of underlying subjective quality factors. The second goal is the application of the developed method within a series of studies in the domain of mobile 3D video and television to show its applicability.Open Profiling of Quality (OPQ) is a mixed-methods research approach which combines a quantitative, psychoperceptual evaluation of hedonic excellence and a descriptive sensory analysis of underlying quality factors based on naive participants' individual vocabulary. This combination allows defining the excellence of overall quality, understanding the characteristics of quality perception, and, eventually, constructing a link between preferences and quality attributes. The method was developed under constructive research with respect to validity and reliability of test results. A series of quality evaluation studies with more than 300 test participants was conducted along different critical components of a system for optimized mobile 3DTV content delivery over DVB-H.The results complemented each other, and, even more importantly, quantitative quality preferences were explained by sensory descriptions in all studies. Beyond the development of OPQ, the thesis proposes further research approaches, e.g. a conventional profiling in which OPQ's individual vacobulary is substituted by a fixed set of Quality ofExperience components or Descriptive Sorted Napping which combines a sorting task and a short post-task interview. All approaches are compared to Open ProVling of Quality at the end of the thesis. To be able to holistically contrast strengths and weaknesses of each method, a comparison model for audiovisual evaluation methods was developed and a Vrst conceptual operationalization of the model was applied in the comparison

Development of Immersive and Interactive Virtual Reality Environment for Two-Player Table Tennis

Although the history of Virtual Reality (VR) is only about half a century old, all kinds of technologies in the VR field are developing rapidly. VR is a computer generated simulation that replaces or augments the real world by various media. In a VR environment, participants have a perception of “presence”, which can be described by the sense of immersion and intuitive interaction. One of the major VR applications is in the field of sports, in which a life-like sports environment is simulated, and the body actions of players can be tracked and represented by using VR tracking and visualisation technology. In the entertainment field, exergaming that merges video game with physical exercise activities by employing tracking or even 3D display technology can be considered as a small scale VR. For the research presented in this thesis, a novel realistic real-time table tennis game combining immersive, interactive and competitive features is developed. The implemented system integrates the InterSense tracking system, SwissRanger 3D camera and a three-wall rear projection stereoscopic screen. The Intersense tracking system is based on ultrasonic and inertia sensing techniques which provide fast and accurate 6-DOF (i.e. six degrees of freedom) tracking information of four trackers. Two trackers are placed on the two players’ heads to provide the players’ viewing positions. The other two trackers are held by players as the racquets. The SwissRanger 3D camera is mounted on top of the screen to capture the player’