Relevant Perceptual Factors in Stereoscopic Displays: Image Disparity, Convergence Distance, and Focus Length

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 185-185
Author(s):  
W A IJsselsteijn ◽  
H de Ridder ◽  
R Hamberg
Keyword(s):  
Subjective Assessment ◽  
Normal Vision ◽  
Quality Model ◽  
Systematic Deviation ◽  
Still Images ◽  
Stereoscopic Displays ◽  
Strong Linear Correlation ◽  
Perceptual Factors ◽  
Relevant Factors

Traditionally, visually relevant factors in stereoscopic displays have been investigated within a performance-oriented framework, focusing on the veridicality of depth perception. However, for some applications, most notably in the areas of broadcasting and entertainment, an appreciation-oriented approach seems to be more relevant. Within this framework, we investigated the influence of image disparity, convergence distance, and focus length on the subjective assessment of depth, naturalness of depth, and quality of depth (or preference). Twelve observers with normal or corrected-to-normal vision and good stereopsis viewed a fully randomised presentation of stereoscopic still images that varied systematically in image disparity (six levels of camera base difference: 0, 4, 8, 12, 16, and 24 cm), convergence distance (two levels: 1.30 m and 2.60 m) and focus length (two levels: 10 mm and 20 mm). Each observer was asked to rate, in separate counterbalanced sessions, his/her impression of depth, naturalness of depth, and quality of depth. The results indicate that observers prefer a stereoscopic presentation of images over a monoscopic presentation. A clear optimum was found at 4 cm image disparity for subjective judgments of naturalness and of quality. Depth judgements increased up to an image disparity of 12 cm, a result that is in line with earlier psychophysical literature. There was an effect of focus length only at extreme image disparities. An effect of convergence distance was also found that can be adequately explained by rescaling to match the effective visual disparities. Although there was a strong linear correlation between naturalness and quality (r = 0.96), a small but systematic deviation could be observed. This deviation was best modelled by a linear quality model that incorporates both naturalness and depth.

Effects of Stereo and Motion Manipulations on Measured Presence in Stereoscopic Displays

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 144-144 ◽  
Author(s):  
J Freeman ◽  
S E Avons ◽  
J Davidoff ◽  
D E Pearson
Keyword(s):  
Sensory Information ◽  
Subjective Assessment ◽  
Tv Viewing ◽  
Stereoscopic Displays ◽  
Continuous Evaluation ◽  
Quality Ratings ◽  
Post Test ◽  
Display Technology ◽  
Being There

Methods of assessing presence, a sense of ‘being there’ within a displayed virtual environment, include post-test subjective measures, discrimination tests, and monitoring reflexive responses. Each is limited—either they do not provide a measure of temporal variation, are not feasible with current display technology or are overly content-specific. A measure of presence derived from the method of continuous evaluation (ITU-R, Recommendation BT.500-7, revised, “Methodology for the subjective assessment of the quality of television pictures”, 1995) has been used to overcome these limitations. The results of two experiments are presented. Those of the first experiment established that the methodology is usable under the optimal viewing conditions for the 20 inch stereoscopic TV display upon which our stimuli were presented. It compares within-subject variation on continuous TV picture quality ratings under two viewing conditions—at six picture heights in the light (standard for quality evaluations) and at two picture heights in the dark (optimal stereo TV viewing). The second experiment investigated the effects of manipulations of the visual parameters of stereo, scene motion, and observer-based motion on participants' presence evaluations within edited sections of a stereoscopic film. The results provide support for theories predicting that the extent of sensory information available to a participant is one of the factors determining presence.

Feasibility and Clinical Implications of Remotely Guided Ultrasound Examinations

2020 ◽  
Vol 91 (7) ◽  
pp. 592-596
Author(s):  
Quinn Dufurrena ◽  
Kazi Imran Ullah ◽  
Erin Taub ◽  
Connor Leszczuk ◽  
Sahar Ahmad
Keyword(s):  
Clinical Utility ◽  
Regional Wall Motion ◽  
Subjective Assessment ◽  
Clinical Implications ◽  
Pilot Studies ◽  
Objective Quality ◽  
The Us ◽  
Regional Wall Motion Abnormalities ◽  
Wall Motion Abnormalities

BACKGROUND: Remotely guided ultrasound (US) examinations carried out by nonmedical personnel (novices) have been shown to produce clinically useful examinations, at least in small pilot studies. Comparison of the quality of such exams to those carried out by trained medical professionals is lacking in the literature. This study compared the objective quality and clinical utility of cardiac and pulmonary US examinations carried out by novices and trained physicians.METHODS: Cardiac and pulmonary US examinations were carried out by novices under remote guidance by an US expert and independently by US trained physicians. Exams were blindly evaluated by US experts for both a task-based objective score as well as a subjective assessment of clinical utility.RESULTS: Participating in the study were 16 novices and 9 physicians. Novices took longer to complete the US exams (median 641.5 s vs. 256 s). For the objective component, novices scored higher in exams evaluating for pneumothorax (100% vs. 87.5%). For the subjective component, novices more often obtained clinically useful exams in the assessment of cardiac regional wall motion abnormalities (56.3% vs. 11.1%). No other comparisons yielded statistically significant differences between the two groups. Both groups had generally higher scores for pulmonary examinations compared to cardiac. There was variability in the quality of exams carried out by novices depending on their expert guide.CONCLUSION: Remotely guided novices are able to carry out cardiac and pulmonary US examinations with similar, if not better, technical proficiency and clinical utility as US trained physicians, though they take longer to do so.Dufurrena Q, Ullah KI, Taub E, Leszczuk C, Ahmad S. Feasibility and clinical implications of remotely guided ultrasound examinations. Aerosp Med Hum Perform. 2020; 91(7):592–596.

scholarly journals Adaptive Reservation of Network Resources According to Video Classification Scenes

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1949
Author(s):  
Lukas Sevcik ◽  
Miroslav Voznak
Keyword(s):  
User Satisfaction ◽  
Quality Evaluation ◽  
Spatial Information ◽  
Service Providers ◽  
Video Quality ◽  
Subjective Assessment ◽  
Video Sequences ◽  
Network Resources ◽  
Proposed Model

Video quality evaluation needs a combined approach that includes subjective and objective metrics, testing, and monitoring of the network. This paper deals with the novel approach of mapping quality of service (QoS) to quality of experience (QoE) using QoE metrics to determine user satisfaction limits, and applying QoS tools to provide the minimum QoE expected by users. Our aim was to connect objective estimations of video quality with the subjective estimations. A comprehensive tool for the estimation of the subjective evaluation is proposed. This new idea is based on the evaluation and marking of video sequences using the sentinel flag derived from spatial information (SI) and temporal information (TI) in individual video frames. The authors of this paper created a video database for quality evaluation, and derived SI and TI from each video sequence for classifying the scenes. Video scenes from the database were evaluated by objective and subjective assessment. Based on the results, a new model for prediction of subjective quality is defined and presented in this paper. This quality is predicted using an artificial neural network based on the objective evaluation and the type of video sequences defined by qualitative parameters such as resolution, compression standard, and bitstream. Furthermore, the authors created an optimum mapping function to define the threshold for the variable bitrate setting based on the flag in the video, determining the type of scene in the proposed model. This function allows one to allocate a bitrate dynamically for a particular segment of the scene and maintains the desired quality. Our proposed model can help video service providers with the increasing the comfort of the end users. The variable bitstream ensures consistent video quality and customer satisfaction, while network resources are used effectively. The proposed model can also predict the appropriate bitrate based on the required quality of video sequences, defined using either objective or subjective assessment.

Study time, glasses utilization and age affect quality of life among senior first-year Chinese myopia students

2021 ◽  
pp. 112067212098252
Author(s):  
Ziqian Zhu ◽  
Yan He ◽  
Jiezheng Yang ◽  
Qiaoli Li ◽  
HuanHuan Cheng ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Risk Factors ◽  
Regression Analysis ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Study Time ◽  
First Year ◽  
Normal Vision ◽  
First Year Students

Purpose: To compare the quality of life of senior first-year students with normal vision and myopia, and to explore the risk factors related to quality of life in students with myopia. Methods: In this study, 1103 senior first-year students were enrolled in ten high schools. These students were divided according to the diopter degree, with 916 myopia students and 187 normal vision students. Visual function indexes, such as naked eye vision, were measured and recorded, and social demographic indexes and the National Eye Institute 25-Item Visual Function Questionnaire (NEI VFQ-25) was used. The differences in quality of life between the two groups were compared. Multiple linear regression analysis was used to explore the possible risk factors for quality of life in myopia students. Results: In the NEI VFQ-25, the total quality of life scores of myopia students (77.06 ± 15.66) were lower than those of normal vision students (85.49 ± 12.37). The difference was statistically significant ( p = 0.007). In the correlation analysis, the total scores of quality of life in myopia students were positively correlated with wearing glasses ( p = 0.049), and were negatively correlated with study time ( p = 0.029). Multiple linear regression analysis showed that study time, wearing glasses and age were risk factors affecting quality of life in myopia students. Conclusion: Our results show that senior first-year myopia students have lower quality of life scores than students with normal vision. Study time, wearing glasses and age are risk factors for quality of life in senior first-year myopia students.

Measuring the Quality of Internet Connectivity Service Rendered to South African Public Libraries

Mousaion ◽  
2021 ◽  
Vol 38 (4) ◽  
Author(s):  
Lesiba Stephen Ledwaba
Keyword(s):  
Service Quality ◽  
South African ◽  
Service Providers ◽  
Public Libraries ◽  
Internet Access ◽  
Quality Model ◽  
Technical Problems ◽  
Internet Connectivity ◽  
Access Service

The measuring of rendered services in any industry, especially in libraries, remains a critical tool to assess the satisfaction level of clients as well as the quality of the services. This article reports on a study that was undertaken to measure the quality of internet access service to South African public libraries by using the service quality model. The paper was guided by these objectives to identify the service quality models applicable to public libraries’ internet access; to determine how the quality of internet access service fits within the South African broadband policy; and to apply service quality dimensions to public libraries’ internet access. The study employed a quantitative approach and survey design in which a questionnaire was used to collect data from 322 heads of public libraries in South Africa. The stratified sampling method was used to obtain a proportional representation of public libraries. It emerged that most respondents regarded their internet service providers (ISPs) as incapable of solving their technical problems. It was further found that in most cases ISPs applied the internet access policies inconsistently to public libraries they served. The study recommended, among others, that internet connectivity to public libraries be centralised and that a competent provider be appointed to manage this service.

scholarly journals Assessment of Fatigue in Multiple Sclerosis

2017 ◽  
Vol 1 (02) ◽  
pp. E79-E85 ◽  
Author(s):  
Carina Sander ◽  
Hans-Ulrich Voelter ◽  
Hans-Peter Schlake ◽  
Paul Eling ◽  
Helmut Hildebrandt
Keyword(s):  
Multiple Sclerosis ◽  
Cognitive Performance ◽  
Causal Relation ◽  
Subjective Assessment ◽  
Clinically Isolated Syndrome ◽  
Professional Activity ◽  
Quality Of Sleep ◽  
Clinical Criteria ◽  
Clinical Interviews

AbstractOne of the most frequent symptoms in multiple sclerosis (MS) is fatigue. It has a major impact on quality of life as well as on professional activity. Even nowadays it is still unclear what constitutes an adequate assessment of the perceived fatigue.The following overview will discuss different possibilities to assess fatigue with the help of questionnaires, clinical interviews or the objective measurement of cognitive performance. Furthermore, a structured guideline for the assessment of fatigue will be proposed. Clinical criteria for MS related fatigue include the main symptoms, their everyday relevance, the possible causal relation with the cause of disease (the underlying MS), as well as an exclusion of other possible somatic or psychological reasons. It is recommended to use the “Würzburger Erschöpfungs-Inventar bei Multipler Sklerose (WEIMUS)” (English: Würzburg Fatigue Inventory for Multiple Sclerosis) and especially the “Fatigue Scale for Motor and Cognitive Functions” (FSMC), as these questionnaires distinguish between motor and cognitive fatigue and due to the larger number of research studies using the FSMC. Moreover, the presence of depression, quality of sleep and daytime sleepiness should be assessed. In addition, general cognitive performance as well as performance during monotonous stimulation (vigilance) should be assessed. This may be relevant for the evaluation of a patient’s capacity to work, and for determining prognosis, as there are indications for a relation to relapse frequency, a change from a clinically isolated syndrome (CIS) to an MS diagnosis with an increase of brain atrophy.All in all, it can be said, that despite the growing convergence of diagnostic criteria, the available studies of the objective as well as the subjective assessment of fatigue are still not sufficient and further research is needed.

scholarly journals Statistical analysis of factors affecting the service quality of Jetstar Pacific Airlines

2015 ◽  
Vol 18 (2) ◽  
pp. 67-75
Author(s):  
Nhan Huu Huynh ◽  
Dung Anh To
Keyword(s):  
Factor Analysis ◽  
Statistical Analysis ◽  
Service Quality ◽  
External Environment ◽  
Technical Quality ◽  
Quality Model ◽  
Factors Affecting ◽  
Functional Quality ◽  
The Relationship

The aim of this paper is to study the effects of service quality in Jetstar Pacific Airlines towards customer’s satisfaction under the perspective of Servqual and Gronroos service quality model and the relationship between functional quality, technical quality, internal and external environment influences mediated by Jetstar Pacific Airlines images and service quality using the main statistical methods such as factor analysis and multiple linear regression.

scholarly journals HEALTH-RELATED QUALITY OF LIFE AMONG DISPENSARY OBSERVATION PATIENTS WITH CHRONIC ILLNESS IN BULGARIA

2017 ◽  
Vol 5 ◽  
pp. 943-947
Author(s):  
Teodora Dimcheva ◽  
Boryana Levterova ◽  
Desislava Bakova ◽  
Nonka Mateva
Keyword(s):  
Quality Of Life ◽  
Chronic Diseases ◽  
Subjective Assessment ◽  
Cross Sectional Study ◽  
Communicable Diseases ◽  
Strong Impact ◽  
Cross Sectional ◽  
Non Communicable Diseases ◽  
Chronic Respiratory Diseases

Introduction: The prevalence of chronic non-communicable diseases (NCDs) worldwide acquires epidemic dimensions. In Europe, five nosological groups (diabetes mellitus, cardiovascular disease, cancer, chronic respiratory diseases and mental disabilities) constitute 77% of NCDs and cause about 86% of deaths in the region.Objectives: This study aimed to assess the quality of life in patients with chronic non-communicable diseases under dispensary observation.Methods: The pilot cross-sectional study was performed among adult with chronic diseases in primary care practices in the Plovdiv district (the second largest in Bulgaria) from May to June 2013.Results: A total of 200 adults with chronic diseases participated in the study. The mean age was 55.6 years (range 25–95, standard deviation (SD) 16.9). The most common chronic diseases in our study were cardiovascular 51% (ischemic heart disease, hypertension, etc.), followed by endocrinology diseases (23%). There was statistically significant differences in the assessments of "general health" in different groups of participants by gender (χ2 = 16.65, P <0.002), age (χ2 = 12.57, P <0.05) and social status (χ2 = 28.54, P <0.0001).Conclusion: The subjective assessment of health is a factor that has a strong impact on the quality of life of patients and is an important component in evaluating the effectiveness of provided health care for patients with chronic non-communicable diseases.

scholarly journals Study of a Context Quality Model for UbiPri Middleware

2020 ◽  
Author(s):  
Diandre de Paula ◽  
Daniel Saraiva ◽  
Romeiro Natália ◽  
Nuno Garcia ◽  
Valderi Leithardt
Keyword(s):  
Quality Indicators ◽  
Data Privacy ◽  
Context Information ◽  
Adaptation Process ◽  
Context Aware ◽  
Quality Model ◽  
Context Aware Computing ◽  
Quality Of Context ◽  
The Impact

With the growth of ubiquitous computing, context-aware computing-based applications are increasingly emerging, and these applications demonstrate the impact that context has on the adaptation process. From the context, it will be possible to adapt the application according to the requirements and needs of its users. Therefore, the quality of the context information must be guaranteed so that the application does not have an incorrect or unexpected adaptation process. But like any given data, there is the possibility of inaccuracy and/or uncertainty and so Quality of Context (QoC) plays a key role in ensuring the quality of context information and optimizing the adaptation process. To guarantee the Quality of Context it is necessary to study a quality model to be created, which will have the important function of evaluating the context information. Thus, it is necessary to ensure that the parameters and quality indicators to be used and evaluated are the most appropriate for a given type of application. This paper aims to study a context quality model for the UbiPri middleware, defining its quality indicators to ensure its proper functioning in the process of adaptation in granting access to ubiquitous environments. Keywords: QoC, Model, Context-Aware, Data, Privacy

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