The emergence of use cases such as immersive telepresence and virtual entertainment, where real life dynamic scenes of humans are captured and reconstructed in 3D, has led to the development of new methods for point cloud compression and quality assessment. However, these methods only consider the coordinates and color attributes of the points. Other properties, such as the normals that describe the surface of the represented object and could improve decoded point cloud rendering, are ignored. In this paper, we add the coding of the normals as attributes in video-based point cloud compression (V-PCC). Through a subjective quality assessment study, we consider the impact of the induced coding distortions on shaded rendering and on the perceived quality of decoded point clouds of digital humans. We demonstrate the relevance of encoding these attributes, and the effect of this new type of distortion on the standard test methodology.

Visual quality assessment of volumetric videos has become an important matter for emerging use cases and applications in eXtended Reality (XR). The results of such experiments can pave the way for upgrades in compression and rendering methods that will improve the Quality of Experience of end users. However, only a few subjective experiments were run to assess the perceived quality of such dynamic content, and no standard methodologies and recommendations have been defined for now. In this paper, we analyze and compare the available results from subjective experiments in XR for the quality assessment of volumetric videos represented as Dynamic Point Clouds. By doing so, we determine the requirements in terms of number of observers for various test and rating methodologies. Our conclusion is a step forward to the definition of common test conditions for dynamic volumetric content in 6DoF subjective quality assessment.

The building industry and the design of interior environments are increasingly focusing on the user experience, incorporating sensory analysis to reconsider how office environments can be optimized. New immersive technologies offer significant opportunities for sensory science, enhancing our understanding of human perception and enabling the collection of multi-sensory data under controlled laboratory conditions. While the potential of Virtual Reality (VR) for these types of studies is well recognized, certain limitations still need to be addressed, including the lack of standardized research practices and the challenge of ensuring the simulated environment closely mirrors the real world. In this study, we compare 360° and 3D formats, to real-life settings in order to determine which format offers greater ecological validity for visual perception and immersion. Additionally, we examine the effects of vibroacoustic stimuli with different levels of intensity on perception and cognition of 30 participants. Subjective, physiological and cognitive data was collected throughout the test to tackle the participant's experience. This preliminary study introduces an immersive methodology that leverages advanced techniques to gain deeper insights into multisensory user experience in VR, marking a significant step forward in the optimization of VR for building evaluation.

Omnidirectional media formats, particularly 360° videos with spatial audio, provide new immersive experiences and introduce a novel dimension to content consumption.We explore the relationship between subjective data quality and metric performance evaluation in the context of Omnidirectional videos with spatial audio. While methodologies for 360° video quality assessment have been standardized and well-documented, previous efforts primarily focus on video with limited audio conditions, e.g., mono/stereo rendering. Moreover, the experimental test setup and subjective test methodologies impact data quality and the ability to use these data for objective quality metrics performance evaluation. Such a problem is key in the industry and the standardization activities, as codecs and quality models must be compared. Hence, the requirements on the ground truth data quality have to be clarified to allow proper conclusions.In this paper, we compare two setups and three test methodologies to study how experiment discriminability changes with conditions and participant number. Then, we show how discriminability impacts the resolving power of quality metrics. We show that higher-performing metrics require higher-quality data to reveal their full potential. In doing so, we put into relation the experimental cost, data quality, and resolving power.

This demo’s objective is to display how simulated environments can be used in the evaluation of work-related indoor environments compared to physical environments. In fact, in indoor environment evaluations, Virtual Reality (VR) offers new possibilities for experimental design as well as a functional rapprochement between the laboratory and real life. With VR, environmental parameters (e.g light, color, furniture...) can be easily manipulated at reasonable costs, allowing to control and guide the user’s sensorial experience. One main challenge is to acknowledge to which extent simulated environments are ecologically valid and which functions would be more solicited in different environmental-simulation display formats. User-centric evaluation and sensory analysis in the building sector is in its beginning; this new tool could be of benefit for the building sector, on one hand for methodological facilitation purposes and on the other for cost reductions. In order to achieve the objectives of this project, a first step is to develop and validate the indoor simulations. In environmental simulations, one of the most used formats, for its visual realism and ease of use are 360° panoramic photos and videos, which permits capturing physical-world images. In an objective of validation of the format, 360° photos of workplaces were taken in the building of Halle 6 Ouest of Nantes University and an immersive and interactive test based on physiological indicators to subjectively and objectively assess comfort and performances in work offices was developed. The demo will comprise a head-mounted display with integrated eye-tracking and the measure of electrodermal activity, heart rate and galvanic skin response.

The building sector and the indoor environment conception is undergoing major changes. There is a need to reconsider the way offices are built from a user’s centric point of view. Research has shown the influence of perceived comfort and satisfaction on performance in the workplace. By understanding how multi-sensory information is integrated into the nervous system and which environmental parameters influence the most perception, it could be possible to improve work environments. With the emergence of new virtual reality (VR) and augmented reality (AR) technologies, the collection and processing of sensory information is rapidly advancing, moving forward more dynamic aspects of sensory perception. Through simulated environments, environmental parameters can be easily manipulated at reasonable costs, allowing control and guiding the user’s sensory experience. Moreover, the effects of contextual and surrounding stimuli on users can be easily collected throughout the test, in the form of physiological and behavioral data. Through the use of indoor simulations, this doctoral research goal is to develop a multi-criteria comfort scale based on physiological indicators under performance constraints. In doing this, it would be possible to define new quality indicators combining the different physical factors adapted to the uses and space. In order to achieve the objectives of this project, the first step is to develop and validate an immersive and interactive methodology for the assessment of multisensory information on comfort and performance in work environments.

Point clouds are acknowledged as an essential data structure to represent 3D objects in many use cases, notably immersive experience settings such as Virtual, Augmented or Mixed Reality. This work is the first part of a research project on immersive Quality Assessment of point clouds in different lighting. In this report, I focus mainly on the physically-based rendering of such data in Unity 3D, and the impact of point cloud compression when considering various lighting conditions on the objects. These first observations and results will serve in the implementation of a 6DoF immersive experiment setting for subjective quality assessment.

Tone-mapping operator (TMO) plays a crucial role in the task towards displaying high dynamic range (HDR) contents on standard displays. Similarly, visual attention (VA) is a vital feature of the human visual system (HVS), while it has not been sufficiently investigated in preference of tone-mapped images. The potential benefits of visual attention-based features for quality assessment of tone-mapped images are studied in this paper. A novel framework is proposed for tone-mapped image quality assessment to predict image preference. The framework is evaluated on two different datasets. Experimental results illustrate the importance of visual attention for improving the performance of objective metrics. The proposed framework outperforms the existing methods and presents as a competitive alternative for tone-mapped images evaluation.

In this paper, we propose a novel framework to characterize a wide color gamut image content based on perceived quality due to the processes that change color gamut, and demonstrate two practical use cases where the framework can be applied. We first introduce the main framework and implementation details. Then, we provide analysis for understanding of existing wide color gamut datasets with quantitative characterization criteria on their characteristics, where four criteria, i.e., coverage, total coverage, uniformity, and total uniformity, are proposed. Finally, the framework is applied to content selection in a gamut mapping evaluation scenario in order to enhance reliability and robustness of the evaluation results. As a result, the framework fulfils content characterization for studies where quality of experience of wide color gamut stimuli is involved.

Visual attention has been shown as a good proxy for QoE, revealing specific visual patterns considering content, system and contextual aspects of a multimedia applications. In this paper, we propose a novel approach based on hidden markov models to analyze visual scanpaths in an image memorability task. This new method ensures the consideration of both temporal and idiosyncrasic aspects of visual behavior. The study shows promising results for the use of indirect measures for the personalization of QoE assessment and prediction.

The recent development of Virtual Reality (VR) technologies and interactive visual content faces some important challenges in multimedia processing and Quality of Experience (QoE). Considering omnidirectional, also called 360-degree, content, one major research topic is the development of reliable visual attention models. In this paper, we present a new dataset to study the influence of emotions on eye behavior in omnidirectional content. This dataset is based on an eye-tracking experiment where 19 observers have assessed emotional valence and arousal dimensions in 360-degree images. Several analyses are then conducted to compare fixation and saccade features, inter-observer saliency congruency and spatial oculomotor biases in positive, neutral and negative content. Results show a significant impact of negative images on visual attention, with more visual agitation and avoidance behavior from larger, longer and faster saccades. However, no obvious difference of eye behavior is found between positive and neutral stimulis on this dataset.

Considering the content dependence of the perceived quality, selection of source content can significantly influence the results of studies related to Quality of Experience. In this paper, we propose an automated content selection method towards wide color gamut stimuli. The framework enables to objectively characterize the content according to its perceptual properties and thus allows to select a representative, diverse, and challenging subsets for various studies. Experimental results validate the reliability and robustness of the proposed framework.

The emergence of UHD video format induces larger screens and involves a wider stimulated visual angle. Therefore, its effect on visual attention can be questioned since it can impact quality assessment, metrics but also the whole chain of video processing and creation. Moreover, changes in visual attention from different viewing conditions challenge visual attention models. In this paper, we present a comparative study of visual attention and viewing behavior on three video datasets in SD, HD and UHD conditions. Then, we propose and assess an improvement for video visual attention models by applying a stimulated visual angle dependent center model.

The emergence of UHD video format induces larger screens and involves a wider stimulated visual angle. Therefore, its effect on visual attention can be questioned since it can impact quality assessment, metrics but also the whole chain of video processing and creation. Moreover, changes in visual attention from different viewing conditions challenge visual attention models. In this paper, we present a new HD and UHD video eye tracking dataset composed of 37 high quality videos observed by more than 35 naive observers. This dataset can be used to compare viewing behavior and visual saliency in HD and UHD, as well as for any study on dynamic visual attention in videos. It is available at http://ivc.univ-nantes.fr/en/databases/HD_UHD_Eyetracking_Videos/.

With the ever-growing availability of multimedia content produced, broadcast and consumed worldwide, subtitling is becoming an essential service to quickly share understandable content. Simultaneously, the increased resolution of the ultra high definition (UHD) standard comes with wider screens and new viewing conditions. Services as the display of subtitles thus require adaptation to better fit the new induced viewing visual angle. This paper aims at evaluating quality of experience of subtitled movies in UHD to propose guidelines for the appearance of subtitles. From an eye-tracking experiment conducted on 68 observers and 30 video sequences, viewing behavior and visual saliency are analyzed with and without subtitles and for different subtitle styles. Various metrics based on eye-tracking data, such as the Reading Index for Dynamic Texts (RIDT), are computed to objectively measure the ease of reading and subtitle disturbance. The results mainly show that doubling the visual angle of subtitles from HD to UHD guarantees subtitle readability without compromising the enjoyment of the video content.

Virtual reality is a good tool to design and assess urban projects and to study perception in cities. Climate perception significantly influences the perception and use of urban spaces, however, virtual urban environments are scarcely represented with different climatic aspects. In this paper, we study the role that visual cues (sky aspect, shadows, sun location, and light effects) specifically play in climate perception (season, daytime and temperature) in virtual urban environments. We present and discuss the data we collected from a recent virtual reality experiment in which ten variations of the climatic context in the same urban space were assessed.

Virtual reality is a good tool to design and assess urban projects and to study perception in cities. Climate perception significantly influences the perception and use of urban spaces; however, virtual urban environments are scarcely represented with different climatic aspects. In this paper, we study the role that visual cues (sky aspect, shadows, sun location, and light effects) specifically play in climate perception (season, daytime and temperature) in virtual urban environments. We present and discuss the data we collected from a recent virtual reality experiment in which ten variations of the climatic context in the same urban space were assessed. The results prove the feasibility of suggesting complex climatic perceptions and thermal feelings by processing only sky, shadow and lighting effects. Furthermore, our results highlight the role of subjective interpretation, personal background and current real-world environment in interpretation and understanding of visual cues. Finally, we show that perceived climate influences global perception of virtual urban environments.

Climatic effects represent the physical signals (temperature, wind, humidity, light) which can have a perceptual impact for human-beings. They significantly influence perception and use of urban spaces. Nevertheless, while virtual environments have been proven as good tools to assess urban projects by non-expert people or to study perception in cities, climatic atmospheres are very seldom integrated in the virtual urban model [Drettakis et al. 2007; Tahrani and Moreau 2007]. Indeed, virtual urban environments are represented in ideal situations: the sky is blue, there are a few white clouds, trees are leafy or flowered and the sun is shining. Thus, participants can rarely experiment various seasons, times of day or weathers and and evaluate the urban design under different climatic or lighting situations.