Objective assessment of region of interest-aware adaptive multimedia streaming quality

Adaptive multimedia streaming relies on controlled adjustment of content bitrate and consequent video quality variation in order to meet the bandwidth constraints of the communication link used for content delivery to the end-user. The values of the easy to measure network-related Quality of Service metrics have no direct relationship with the way moving images are perceived by the human viewer. Consequently variations in the video stream bitrate are not clearly linked to similar variation in the user perceived quality. This is especially true if some human visual system-based adaptation techniques are employed. As research has shown, there are certain image regions in each frame of a video sequence on which the users are more interested than in the others. This paper presents the Region of Interest-based Adaptive Scheme (ROIAS) which adjusts differently the regions within each frame of the streamed multimedia content based on the user interest in them. ROIAS is presented and discussed in terms of the adjustment algorithms employed and their impact on the human perceived video quality. Comparisons with existing approaches, including a constant quality adaptation scheme across the whole frame area, are performed employing two objective metrics which estimate user perceived video quality

GazeStereo3D: seamless disparity manipulations

Producing a high quality stereoscopic impression on current displays is a challenging task. The content has to be carefully prepared in order to maintain visual comfort, which typically affects the quality of depth reproduction. In this work, we show that this problem can be significantly alleviated when the eye fixation regions can be roughly estimated. We propose a new method for stereoscopic depth adjustment that utilizes eye tracking or other gaze prediction information. The key idea that distinguishes our approach from the previous work is to apply gradual depth adjustments at the eye fixation stage, so that they remain unnoticeable. To this end, we measure the limits imposed on the speed of disparity changes in various depth adjustment scenarios, and formulate a new model that can guide such seamless stereoscopic content processing. Based on this model, we propose a real-time controller that applies local manipulations to stereoscopic content to find the optimum between depth reproduction and visual comfort. We show that the controller is mostly immune to the limitations of low-cost eye tracking solutions. We also demonstrate benefits of our model in off-line applications, such as stereoscopic movie production, where skillful directors can reliably guide and predict viewers' attention or where attended image regions are identified during eye tracking sessions. We validate both our model and the controller in a series of user experiments. They show significant improvements in depth perception without sacrificing the visual quality when our techniques are applied

Gaze-contingent training enhances perceptual skill acquisition.

The purpose of this study was to determine whether decision-making skill in perceptual-cognitive tasks could be enhanced using a training technique that impaired selective areas of the visual field. Recreational basketball players performed perceptual training over 3 days while viewing with a gaze-contingent manipulation that displayed either (a) a moving window (clear central and blurred peripheral vision), (b) a moving mask (blurred central and clear peripheral vision), or (c) full (unrestricted) vision. During the training, participants watched video clips of basketball play and at the conclusion of each clip made a decision about to which teammate the player in possession of the ball should pass. A further control group watched unrelated videos with full vision. The effects of training were assessed using separate tests of decision-making skill conducted in a pretest, posttest, and 2-week retention test. The accuracy of decision making was greater in the posttest than in the pretest for all three intervention groups when compared with the control group. Remarkably, training with blurred peripheral vision resulted in a further improvement in performance from posttest to retention test that was not apparent for the other groups. The type of training had no measurable impact on the visual search strategies of the participants, and so the training improvements appear to be grounded in changes in information pickup. The findings show that learning with impaired peripheral vision offers a promising form of training to support improvements in perceptual skill

Evaluation of the Tobii EyeX Eye tracking controller and Matlab toolkit for research

The Tobii Eyex Controller is a new low-cost binocular eye tracker marketed for integration in gaming and consumer applications. The manufacturers claim that the system was conceived for natural eye gaze interaction, does not require continuous recalibration, and allows moderate head movements. The Controller is provided with a SDK to foster the development of new eye tracking applications. We review the characteristics of the device for its possible use in scientific research. We develop and evaluate an open source Matlab Toolkit that can be employed to interface with the EyeX device for gaze recording in behavioral experiments. The Toolkit provides calibration procedures tailored to both binocular and monocular experiments, as well as procedures to evaluate other eye tracking devices. The observed performance of the EyeX (i.e. accuracy < 0.6°, precision < 0.25°, latency < 50 ms and sampling frequency ≈55 Hz), is sufficient for some classes of research application. The device can be successfully employed to measure fixation parameters, saccadic, smooth pursuit and vergence eye movements. However, the relatively low sampling rate and moderate precision limit the suitability of the EyeX for monitoring micro-saccadic eye movements or for real-time gaze-contingent stimulus control. For these applications, research grade, high-cost eye tracking technology may still be necessary. Therefore, despite its limitations with respect to high-end devices, the EyeX has the potential to further the dissemination of eye tracking technology to a broad audience, and could be a valuable asset in consumer and gaming applications as well as a subset of basic and clinical research settings

Análisis de las características de la visión periférica y la ceguera por falta de atención para la aceleración del rendering en aplicaciones

En este trabajo se realizaron experimentos de percepción visual en la periferia del sistema de visión, explotando el efecto de ceguera por falta de atención, y con el objeto de acelerar el rendering en aplicaciones 3d, como video juegos y mundos virtuales.López Luro, FG. (2009). Análisis de las características de la visión periférica y la ceguera por falta de atención para la aceleración del rendering en aplicaciones. http://hdl.handle.net/10251/14213Archivo delegad

Keep Your Eyes above the Ball: Investigation of Virtual Reality (VR) Assistive Gaming for Age-Related Macular Degeneration (AMD) Visual Training

Humans are beyond all visual beings since most of the outside information is gathered through the visual system. When the aging process starts, visual functional damages become more and more common and the risk of developing visual impairment is higher. Age-related macular degeneration (AMD) is one of the main afflictions that leads to severe damage to the optical system due to the aging process. The ones affected lose the ability to use the central part of vision, essential for accurate visual information processing. Even if less accurate, peripheral vision remains unaffected, hence medical experts have developed training procedures to train patients to use peripheral vision instead to navigate their environment and continue their daily lives. This type of training is called eccentric viewing. However, there are several shortcomings in current approaches, such as not being engaging or individualizable enough nor cost and time-effective. The main scope of this dissertation was to find out if more engaging and individualizable methods can be used for peripheral training of AMD patients. The current work used virtual reality (VR) gaming to deliver AMD training; the first time such an approach was used for eccentric viewing training. In combination with eye-tracking, real-time individualized assistance was also achieved. Thanks to an integrated eye-tracker in the headset, concentric gaze-contingent stimuli were used to redirect the eyes toward an eccentric location. The concentric feature allowed participants to choose freely and individually their peripheral focus point. One study investigated the feasibility a VR system for individualized visual training of ophthalmic patients, two studies investigated two types of peripheral stimuli (three spatial cues and two optical distortions) and the last study was a case study looking into the feasibility of such an approach for a patient with late AMD. Changes in gaze directionality were observed in all the last three studies for one specific spatial cue, a concentric ring. In accordance with the literature, the gaze was directed spontaneously toward the most effective peripheral position. The last study additionally proved gaming feasible for future testing of the elderly AMD population. The current work opened the road to more individualized and engaging interventions for eccentric viewing training for late AMD

Online mouse tracking as a measure of attention in videos, using a mouse-contingent bi-resolution display

Master of ScienceDepartment of Psychological SciencesLester C LoschkyData on human visual attention is increasingly collected online, but there are limited tools available to study attention to video stimuli in online experiments. Webcam-based eye tracking is improving, but it faces issues with precision and attrition that prevent its adoption by many researchers. Here I detail an alternative mouse-based paradigm that can be used to measure attention to videos online. This method uses a blurred display and a high-resolution window centered on the user’s computer mouse location. As the user moves their mouse to view different screen content, their mouse movements are recorded, providing an approximation of eye movements and the attended screen location. To validate this Mouse-Contingent Bi-Resolution Display (MCBRD) paradigm, mouse movements collected from online participants watching twenty-seven videos were compared to eye movements from the DIEM dataset. Display settings of window size and blur level were manipulated to identify the settings that resulted in mouse movements most similar to eye movements. This validation study found differences in speed between mouse and eye movements, but similarities in attended regions of interest, especially when the MCBRD screen was blurred with the highest tested Gaussian blur sigma of 0.45 degrees of visual angle. These results suggest that the MCBRD paradigm can be used to measure what regions viewers find salient, interesting, or visually informative in online videos

The spatiotemporal dynamics of visual attention during real-world event perception

Doctor of PhilosophyDepartment of Psychological SciencesLester LoschkyEveryday event perception requires us to perceive a nearly constant stream of dynamic information. Although we perceive these events as being continuous, there is ample evidence that we “chunk” our experiences into manageable bits (Zacks & Swallow, 2007). These chunks can occur at fine and coarse grains, with fine event segments being nested within coarse-grained segments. Individual differences in boundary detection are important predictors for subsequent memory encoding and retrieval and are relevant to both normative and pathological spectra of cognition. However, the nature of attention in relation to event structure is not yet well understood. Attention is the process which suppresses irrelevant information while facilitating the extraction of relevant information. Though attentional changes are known to occur around event boundaries, it is still not well understood when and where these changes occur. A newly developed method for measuring attention, the Gaze-Contingent Useful Field of View Task (GC-UFOV; Gaspar et al., 2016; Ringer, Throneburg, Johnson, Kramer, & Loschky, 2016; Ward et al., 2018) provides a means of measuring attention across the visual field (a) in simulated real-world environments and (b) independent of eccentricity-dependent visual constraints. To measure attention, participants performed the GC-UFOV task while watching pre-segmented videos of everyday activities (Eisenberg & Zacks, 2016; Sargent et al., 2013). Attention was probed from 4 seconds prior to 6 seconds after coarse, fine, and non-event boundaries. Afterward, participants’ memories for objects and event order were tested, followed by event segmentation. Attention was predicted to either become impaired (attentional impairment hypothesis), or it was predicted to be broadly distributed at event boundaries and narrowed at event middles (the ambient-to-focal shift hypothesis). The results showed marginal evidence for both attentional impairment and ambient-to-focal shift hypotheses, however model fitness was equal for both models. The results of this study were then used to develop a proposed program of research to further explore the nature of attention during event perception, as well as the ability of these two hypotheses to explain the relationship between attention and memory during real-world event perception

Serious Games and Mixed Reality Applications for Healthcare

Virtual reality (VR) and augmented reality (AR) have long histories in the healthcare sector, offering the opportunity to develop a wide range of tools and applications aimed at improving the quality of care and efficiency of services for professionals and patients alike. The best-known examples of VR–AR applications in the healthcare domain include surgical planning and medical training by means of simulation technologies. Techniques used in surgical simulation have also been applied to cognitive and motor rehabilitation, pain management, and patient and professional education. Serious games are ones in which the main goal is not entertainment, but a crucial purpose, ranging from the acquisition of knowledge to interactive training.These games are attracting growing attention in healthcare because of their several benefits: motivation, interactivity, adaptation to user competence level, flexibility in time, repeatability, and continuous feedback. Recently, healthcare has also become one of the biggest adopters of mixed reality (MR), which merges real and virtual content to generate novel environments, where physical and digital objects not only coexist, but are also capable of interacting with each other in real time, encompassing both VR and AR applications.This Special Issue aims to gather and publish original scientific contributions exploring opportunities and addressing challenges in both the theoretical and applied aspects of VR–AR and MR applications in healthcare