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Investigating visual discomfort with 3D displays: the stereoscopic discomfort scale
Abstract
Notwithstanding their widespread diffusion, stereoscopic media have important drawbacks in terms of viewers' visual discomfort. Current assessment methods are mainly based on measures of objective parameters such as eye physiology or media characteristics. On the other hand, subjective methods only evaluate the personal experience related to the physiological symptoms. In this pilot study we developed and validated the Stereoscopic Discomfort Scale (SDS), a self-assessment tool for the subjective evaluation of physiological and psychological symptoms related to stereoscopic viewing. The results show evidence of internal consistency, unidimensionality and construct validity of the scale. Since SDS scores were also strongly correlated with facets of presence, we argue that the SDS could be a useful tool for the investigation of users' experience related to stereoscopic media.
... The Convergence Insufficiency Symptom Survey (CISS) by Lambooij et al. addressed different aspects of discomfort , such as double vision and and sleepiness [81], and Yang et al. added psychological factors such as impaired memory, disorientation, dizziness and vertigo [179] . The Stereoscopic Discomfort Scale (SDS) of Bracco et al. combines previous measures and extends them with new ones in order to create a more complete standard [18]. Unfortunately, none of these scales has been widely adopted, and many are still based on the ITU scale, making comparisons difficult. ...
This paper reviews the causes of discomfort in viewing stereoscopic content. These include objective factors, such as misaligned images, as well as subjective factors, such as excessive disparity. Different approaches to the measurement of visual discomfort are also reviewed, in relation to the underlying physiological and psychophysical processes. The importance of understanding these issues, in the context of new display technologies, is emphasized.
Background:
To regain 2-eyed vision in laparoscopy, dual-channeled optics have been introduced. With this optics design, the distance between the 2 front lenses defines how much stereoscopic effect is seen. This study quantifies the impact of an enhanced and a reduced stereo effect on surgical task efficiency.
Methods:
A prospective single-blinded study was performed with 20 laparoscopic novices in an inanimate experimental setting. A standard bichannelled stereo system was used to perform a suturing and knotting task. The working distance and the task size were scaled to vary the stereo effect and, thereby, simulate hypothetic stereo optics with enhanced and reduced optical bases. The task performances were timed, and the number of trials for stitching out was counted. The participants finally filled out a questionnaire to collect subjective impressions.
Results:
The increase of the stereo effect by 50% caused no objective improvement in laparoscopic knotting compared with typical 3D (control group with stereo basis of 4.5 mm). But ergonomic disadvantages (headache) were subjectively reported in 1 of 20 cases in the questionnaire. The reduction of the stereo effect by one-third led to a significantly longer average execution time. There was no significant dependence found between stereo effect and number of stich-out trials, stitching precision, or knotting quality.
Conclusions:
Considering laparoscopy, it does not seem advisable to enhance the stereo effect because of ergonomic problems. Otherwise, a miniaturization of the 3D scope (5 mm version) is problematic because its benefit mostly shrinks with the reduced stereo effect.
Virtual Reality for desktop or table mounted display environments can be a strong tool in supporting users in sighting spatial information and give a better understanding in their spatial relationships. Visualization of spatial data incorporates spatial interaction and manipulation with six degrees of freedom for data processing which is part of current research objectives. Modern tracking devices for desktop applications allow capturing a model of the human hand with three translational and three rotatory degrees of freedom which can be used as an input system allowing the control over a virtual hand model in a stereoscopic desktop system. Interaction with complex data in rich environments using virtual hand models, such as three-dimensional geographic information systems with integrated spatial data, requires visualization with a low degree of occluding virtual entities in the virtual scene but a high degree of recognition. An experimental task using a Fitts’ pointing task is conducted to investigate different minimalistic modeling approaches of virtual hand models using the Leap Motion Controller in a stereoscopic desktop environment. Movement times are analyzed for pointing movements in three different depth layers. Results indicate that a kinematic visualization of a virtual hand model produces significantly better movement times in pointing over a minimalistic point cloud model.
— This research identifies methods for signs of visual complaints associated with stereoscopic displays. Two potential causes for contradictory results concerning these signs in previous research are hypothesized: (1) not all clinical tests are equally appropriate and (2) there is a natural variation in susceptibility amongst people with normal vision. An optometric screening differentiated participants with moderate binocular status (MBS) from those with good binocular status (GBS). In a 2 × 2 within-subjects design (2-D vs. 3-D and MBS vs. GBS), a questionnaire and eight optometric tests (i.e., binocular acuity, aligning prism, fixation disparity, heterophoria, convergent and divergent fusional reserves, vergence facility, and accommodation response) were each administered before and immediately after a reading task. Results revealed that only participants with MBS in 3-D conditions showed clinically meaningful changes in fusion range, experienced more visual discomfort, and performed worse on the reading task. Acombination of fusion range measurements and self-report is appropriate for evaluating visual complaints of stereoscopic stills, and people with a MBS are more susceptible to visual complaints associated with stereoscopic displays. A simple measurement tool, i.e., the ratio of reading performance between 2-D and 3-D, to categorize people based on their binocular status is proposed.
Visual discomfort has been the subject of considerable research in relation to stereoscopic and autostereoscopic displays. In this paper, the importance of various causes and aspects of visual discomfort is clarified. When disparity values do not surpass a limit of 1 °, which still provides sufficient range to allow satisfactory depth perception in stereoscopic television, classical determinants such as excessive binocular parallax and accommodation-vergence conflict appear to be of minor importance. Visual discomfort, however, may still occur within this limit and we believe the following factors to be the most pertinent in contributing to this: (1) temporally changing demand of accommodation-vergence linkage, e.g., by fast motion in depth; (2) three-dimensional artifacts resulting from insufficient depth information in the incoming data signal yielding spatial and temporal inconsistencies; and (3) unnatural blur. In order to adequately characterize and understand visual discomfort, multiple types of measurements, both objective and subjective, are required.
p> Background : The increasing popularity of tri-dimensional (3D) movies has raised public concern and media interest about the safety of projected images for spectators. No specific instrument exists to assess the occurrence of visually induced motion sickness (VIMS) symptoms in 3D movie spectators in movie theaters.
Methods : We developed a questionnaire containing 20 items divided into socio demographics, individual characteristics, movie vision characteristics and VIMS symptoms (during, right after, and at two hours from the viewing of the movie ). The questionnaire was self administered to 38 subjects, asking them to report time taken for its completion, comments and eventual difficulties in interpreting items.
Results : Poor understanding or problems in identifying the correct item choice were noted for 4 questions belonging to the socio demographics section that were simplified in the final version of the questionnaire. Two other questions were merged into one after homogeneity analysis. Most VIMS symptoms were observed during the movie and quickly thereafter. Tired eyes was the symptom most often reported (39.5% of responders) followed by headache (18.4%), dizziness (18.4%) and nausea (15.8%). Double vision and palpitation were reported with very low frequency (respectively 5.3% and 2.3%) and vomit was not reported by any respondent. Homogeneity of symptom items was good (Cronbach alpha= 0.69). Reliability analysis showed satisfactory item-total correlations (alpha coefficient ranging from 0.61 to 0.73).
Conclusions : The refined survey questionnaire can be applied in future studies to assess the frequency of VIMS symptoms in spectators of 3D movies and to identify the risk factors connected to inter-individual differences in susceptibility and to the characteristics of the movie viewing.</p
The current study challenges traditional approaches to Visual-Verbal cognitive style as a unitary bipolar dimension, and instead suggests a new three-dimensional cognitive style model developed on the basis of modern cognitive science theories that distinguish between object imagery, spatial imagery and verbal dimensions. The results of the confirmatory factor analysis demonstrated that the overall fit to the data of the new three-dimensional model of cognitive style was significantly better than that of a traditional model. Furthermore, based on the new theoretical model, we designed and validated a new self-report instrument assessing the individual differences in object imagery, spatial imagery and verbal cognitive styles, the Object-Spatial Imagery and Verbal Questionnaire (OSIVQ). Across a series of studies, the OSIVQ demonstrated acceptable internal reliability as well as construct, criterion and ecological validity. The current study supports the validity of an object-spatial-verbal cognitive style dimension and related measures when developed on the basis of modern cognitive science theories. Copyright © 2008 John Wiley & Sons, Ltd.
Imperfections in binocular image pairs can cause serious viewing discomfort. For example, in stereo vision systems eye strain is caused by unintentional mismatches between the left and right eye images (stereo imperfections). Head-mounted displays can induce eye strain due to optical misalignments. We have experimentally determined the level of (dis)comfort experienced by human observers viewing brief presentations of imperfect binocular image pairs. We used a wide range of binocular image imperfections that are representative for commonly encountered optical errors (spatial distortions: shifts, magnification, rotation, keystone), imperfect filters (photometric asymmetries: luminance, color, contrast, crosstalk), and stereoscopic disparities. The results show that nearly all binocular image asymmetries seriously reduce visual comfort if present in a large enough amount. From our data we estimate threshold values for the onset of discomfort. The database collected in this study allows a more accurate prediction of visual comfort from the specification of a given binocular viewing system. Being able to predict the level of visual discomfort from the specification of binocular viewing systems greatly helps the design and selection process. This paper provides the basis.
People with some signs of binocular dysfunctioning can be susceptible to visual complaints associated with viewing stereoscopic content at large viewing distances. Two performance measurements enabled to distinguish people by their binocular status (BS) in previous research: the ratio of performance of the Wilkins rate of reading test (WRRT) between 2-D and 3-D, and the vergence facility. In an experiment, first, an extensive optometric screening was carried out to differentiate visually asymptomatic young adults with good BS (GBS) $({N}=27)$ from those with a moderate BS (MBS) $({N}=6)$. Second, participants had to perform the WRRT at short viewing distance followed by a questionnaire under different screen disparity settings. The results reveal that the ratio of the WRRT between 0 and ${-}{1.5}$ screen disparity is an appropriate indicator of participants with MBS in comparison with participants with GBS. In addition, the results show that 0.75$^{\circ}$ of screen disparity is already problematic for people with MBS. We conclude that the WRRT-ratio has potential as a BS test in consumer applications to provide individual settings for comfortable screen disparities based on viewers' BS.
The presence research community would benefit from a reliable and valid cross- media presence measure that allows results from different laboratories to be com- pared and a more comprehensive knowledge base to be developed. The ITC-Sense of Presence Inventory (ITC-SOPI) is a new state questionnaire measure whose de- velopment has been informed by previous research on the determinants of pres- ence and current self-report measures. It focuses on users' experiences of media, with no reference to objective system parameters. More than 600 people com- pleted the ITC-SOPI following an experience with one of a range of noninteractive and interactive media. Exploratory analysis (principal axis factoring) revealed four factors: Sense of Physical Space, Engagement, Ecological Validity, and Negative Ef- fects. Relations between the factors and the consistency of the factor structure with others reported in the literature are discussed. Preliminary analyses described here demonstrate that the ITC-SOPI is reliable and valid, but more rigorous testing of its psychometric properties and applicability to interactive virtual environments is re- quired. Subject to satisfactory confirmatory analyses, the ITC-SOPI will offer re- searchers using a range of media systems a tool with which to measure four facets of a media experience that are putatively related to presence.
Recent increased usage of stereo displays has been accompanied by public concern about potential adverse effects associated with prolonged viewing of stereo imagery. There are numerous potential sources of adverse effects, but we focused on how vergence-accommodation conflicts in stereo displays affect visual discomfort and fatigue. In one experiment, we examined the effect of viewing distance on discomfort and fatigue. We found that conflicts of a given dioptric value were slightly less comfortable at far than at near distance. In a second experiment, we examined the effect of the sign of the vergence-accommodation conflict on discomfort and fatigue. We found that negative conflicts (stereo content behind the screen) are less comfortable at far distances and that positive conflicts (content in front of screen) are less comfortable at near distances. In a third experiment, we measured phoria and the zone of clear single binocular vision, which are clinical measurements commonly associated with correcting refractive error. Those measurements predicted susceptibility to discomfort in the first two experiments. We discuss the relevance of these findings for a wide variety of situations including the viewing of mobile devices, desktop displays, television, and cinema.
Some people report visual discomfort when watching 3D displays. For both the objective measurement of visual fatigue and the subjective measurement of visual discomfort, we would like to arrive at general indicators that are easy to apply in perception experiments. Previous research yielded contradictory results concerning such indicators. We hypothesize two potential causes for this: 1) not all clinical tests are equally appropriate to evaluate the effect of stereoscopic viewing on visual fatigue, and 2) there is a natural variation in susceptibility to visual fatigue amongst people with normal vision. To verify these hypotheses, we designed an experiment, consisting of two parts. Firstly, an optometric screening was used to differentiate participants in susceptibility to visual fatigue. Secondly, in a 2x2 within-subjects design (2D vs 3D and two-view vs nine-view display), a questionnaire and eight optometric tests (i.e. binocular acuity, fixation disparity with and without fusion lock, heterophoria, convergent and divergent fusion, vergence facility and accommodation response) were administered before and immediately after a reading task. Results revealed that participants found to be more susceptible to visual fatigue during screening showed a clinically meaningful increase in fusion amplitude after having viewed 3D stimuli. Two questionnaire items (i.e., pain and irritation) were significantly affected by the participants’ susceptibility, while two other items (i.e., double vision and sharpness) were scored differently between 2D and 3D for all participants. Our results suggest that a combination of fusion range measurements and self-report is appropriate for evaluating visual fatigue related to 3D displays.
Male and female subjects who differed in their verbal reports of visual image vividness were tested for recall in three experiments involving coloured photographs as stimuli. In all three experiments subjects who reported vivid visual imagery were more accurate in recall than subjects who reported poor visual imagery. In the first two experiments, females recalled more accurately than males. On the assumption that vividness reports and recall were both mediated by the same covert event - a visual image - these results provide further evidence that images have an important role in memory.
The relationship between visual comfort and parallax distribution for stereoscopic HDTV has been studied. In this study, we first examined a method for measuring this parallax distribution. As it is important to understand the characteristics of the distribution in a frame or temporal changes of the characteristics, rather than having detailed information on the parallax at every point, we propose a method to measure the parallax based on the phase correlation. It includes a way of reducing the measurement error depending on the phase correlation method. The method was used to measure stereoscopic HDTV images with good results. Secondly, we conducted a subjective evaluation test of visual comfort and sense of presence using 48 different stereoscopic HDTV pictures, and compared the results with the parallax distributions in these pictures measured by the proposed method. The comparison showed that the range of parallax distribution and the average parallax distribution significantly affect visual comfort when viewing stereoscopic HDTV images. It is also suggested that the range of parallax distribution in many of the images that were judged comfortable to view is located within approximate 0.3Diopter.
To gain knowledge on how visual discomfort is built up while watching stereoscopic content an experiment was designed with two objectives: (1) to compare the continuous evaluation method with other assessment methods that potentially can substitute the continuous evaluation for the assessment of visual discomfort of e.g., feature-length movies, and (2) to relate the impact of time-variant content characteristics, such as motion and disparity, to the assessment of visual discomfort. In an experiment a 24 min 3D movie 'Spy Kids 3-D: game over' converted from 2D to 3D was displayed on a 9-view autostereoscopic lenticular LCD, and continuously assessed in terms of visual comfort by 24 participants. Additional assessment methods included the assessment of six 10 s sequences captured from the 3D movie and a single retrospective assessment of the entire 3D movie. Time-variant content characteristics, such as derivatives of motion and screen disparity values, were extracted from the 3D movie with motion and depth estimation algorithms. The moment-to-moment values of these characteristics were correlated to the continuous assessment scores of visual discomfort. With respect to the first objective, results reveal that the correlation between the assessment of the 10 s sequences captured from the 3D movie and their corresponding part within the continuous assessment is low, whereas the correlation between the retrospective assessment and the mean of the continuous assessment score over scene parts with a high screen disparity is higher. With respect to the second objective, for static scenes the visual comfort can be largely described by the screen disparity offset and range. For dynamic scenes the visual comfort is largely related to the screen disparity range, lateral motion and to the change in screen disparity.
Administered a questionnaire containing items of varied content believed to be related to hypnotizability to 481 female undergraduates. 2 subsamples of 142 and 171 Ss, respectively, also completed Block's Ego Resiliency and Ego Control questionnaire scales and the Group Scales of Hypnotic Susceptibility. Analysis of the combined questionnaire data yielded 3 replicated higher order factors: the familiar dimensions of Stability and Introversion and a 3rd factor, Absorption. Absorption is interpreted as a disposition for having episodes of "total" attention that fully engage one's representational (i.e., perceptual, enactive, imaginative, and ideational) resources. This kind of attentional functioning is believed to result in a heightened sense of the reality of the attentional object, imperviousness to distracting events, and an altered sense of reality in general, including an empathically altered sense of self. Only Absorption was consistently correlated with hypnotizability. Absorption appears to be of interest for the study of hypnosis and personality. (38 ref)
Any of several conditions can cause asthenopia. The purpose of this study was to determine whether the particular sensations or their location vary dependent on the symptom-inducing condition.
Twenty subjects with good vision performed eight reading tasks in random order during different conditions. Each condition used different stimuli to induce asthenopia. The eight conditions were mixed astigmatism, close viewing distance, upward gaze, dry eyes, lens flipper, small font, glare, and flickering light. Subjects were asked to read until attaining a level of discomfort self-defined as "barely tolerable." After each task, subjects rated the magnitude of several symptom descriptors (burning, ache, strain, irritation, tearing, blurred vision, double vision, dryness, and headache) and their location.
Analysis of variance with repeated measures was used to determine that all of the individual symptom sensation measures (except blur) were significantly related (p values ranged from 0.003 to <0.0001) to the inducing condition. Principal factor analysis with orthogonal varimax rotation was used to test symptom by condition relationships and determined two latent factors, designated external and internal symptom factors (ESF and ISF), that related symptoms to inducing condition. The ESF pattern comprises burning, irritation, tearing, and dryness located in the front and bottom of the eye. ESF is caused by holding the eyelid open, glare, up gaze, small font, and flickering. ESF seems highly related to dry-eye symptoms. The ISF pattern comprises ache, strain, and headache located behind the eyes. ISF is caused by the close viewing distance, lens flipper, and mixed astigmatism conditions and is likely related to accommodative and vergence stress.
Symptom descriptors and locations were able to distinguish discomfort on the basis of causative condition. Results support two different symptom constellations and, hence, at least two different afferent pathways for symptoms of asthenopia.
500-11, Methodology for the subjective assessment of the quality of television pictures, Question ITU-R 211
- Itu-R Recommendation
- Bt
Recommendation ITU-R BT.500-11, Methodology
for the subjective assessment of the quality of
television pictures, Question ITU-R 211/11.
Methodology for the subjective assessment of the quality of television pictures Question ITU-R 211/11. Recommendation ITU-R BT.500--11 Methodology for the subjective assessment of the quality of television pictures Question
- Itu-R Recommendation
- Bt
Recommendation ITU-R BT.500-11, Methodology
for the subjective assessment of the quality of
television pictures, Question ITU-R 211/11.
Individual Differences and Seating Position Affect Immersion and Symptoms in Stereoscopic 3D Viewing
- S Yang
- T Schlieski
- S Cooper
- R Doherty
- P J Corriveau
- J E Sheedy
S. Yang, T. Schlieski, S. Cooper, R. Doherty, P.J.
Corriveau, J.E. Sheedy, Individual Differences and
Seating Position Affect Immersion and Symptoms in
Stereoscopic 3D Viewing, Optometry and Vision
Science, Vol. 89, NO.7, 2012.
Heynderickx, Visual discomfort and visual fatigue in stereoscopic displays: a review
- M T M Lambooij
- W A Jsselsteijn
- M Fortuin
- I Heynderickx
- Lambooij W.A.