Stereoscopic Distortion Research Articles

Stereoscopic distortions when viewing geometry does not match inter-pupillary distance

Stereoscopic distortions when viewing geometry does not match inter-pupillary distance

Perceptual quality assessment of 3D videos with stereoscopic degradations

In the last decade, several aspects of the 3D video technology have been improved, including the 3D content production, distribution, and display. Still, the level of acceptability and popularity of 3D video applications are strongly correlated to the user Quality of Experience (QoE). Since research in this area depends heavily on data acquired in psychophysical experiments, public databases with typical stereoscopic degradations are considered important tools to researchers. Although currently there are number of available public 3D video quality databases, most of them contain only compression and transmission degradations. In this work, our first goal was to build a database (UnB-3D) that contains stereoscopic distortions. We created a set of Computer Graphics Imaging (CGI) scenes and rendered it using different parameters, generating 3D videos containing stereoscopic degradations at different strengths. Our second goal is to understand how these stereoscopic degradations are perceived by viewers. So, we performed a psychophysical experiment to analyze the perceived quality and comfort of these videos. Finally we conducted the statistical analysis and model generation. Results shows that users that have little familiarity with 3D content have difficulties identifying stereoscopic distortions. Also, the source content has a great influence on the user’s comfort. Similarly, the 3D quality is affected by the spatial and temporal information of the content, specially when the disparity is high.

The Enright phenomenon. Stereoscopic distortion of perceived driving speed induced by monocular pupil dilation

PurposeThe Enright phenomenon describes the distortion in speed perception experienced by an observer looking sideways from a moving vehicle when viewing with interocular differences in retinal image brightness, usually induced by neutral density filters. We investigated whether the Enright phenomenon could be induced with monocular pupil dilation using tropicamide. MethodsWe tested 17 visually normal young adults on a closed road driving circuit. Participants were asked to travel at Goal Speeds of 40km/h and 60km/h while looking sideways from the vehicle with: (i) both eyes with undilated pupils; (ii) both eyes with dilated pupils; (iii) with the leading eye only dilated; and (iv) the trailing eye only dilated. For each condition we recorded actual driving speed. ResultsWith the pupil of the leading eye dilated participants drove significantly faster (by an average of 3.8km/h) than with both eyes dilated (p=0.02); with the trailing eye dilated participants drove significantly slower (by an average of 3.2km/h) than with both eyes dilated (p<0.001). The speed, with the leading eye dilated, was faster by an average of 7km/h than with the trailing eye dilated (p<0.001). There was no significant difference between driving speeds when viewing with both eyes either dilated or undilated (p=0.322). ConclusionsOur results are the first to show a measurable change in driving behaviour following monocular pupil dilation and support predictions based on the Enright phenomenon.

New stereo shooting evaluation metric based on stereoscopic distortion and subjective perception

In this paper, we examined the stereoscopic distortion by varying image acquisition parameters including but not limited to inter-camera distance, camera focal length, and shooting distance. Since a lot of new elements or problems about stereoscopic perception have not been considered or precisely defined before, an advanced shooting principle is raised in this paper to guarantee the overall quality of stereoscopic images. In this paper, based on stereoscopic distortion and features of camera configurations, we present new shooting formulae for both toed-in and parallel camera configurations. Besides, a new shooting evaluation metric is proposed for the evaluation of stereo camera quality. The experimental results show that the proposed approach can precisely assess the visual perception quality of stereo images according to the shooting parameters and can effectively evaluate the quality of stereo camera.

Visual experience for autostereoscopic 3D projection display

In order to investigate visual experience for watching the autostereoscopic three-dimensional (3D) projection display, we conduct a subjective evaluation experiment by a questionnaire when viewing video clips. Factor analysis is adopted to classify the evaluation items for the perpetual constructs of visual experience. Then a mixed design with repeated measurement analysis of variance with dimension and display duration as factors is carried out on the evaluation data to check the factorial effects and interactions for statistical significance. The results of factor analysis extract five factors including visual comfort, image quality, distortion, naturalness, and presence, which can be used as comprehensive indicators to evaluate the autostereoscopic 3D projection display. The results of analysis of variance indicate that image quality, which is used to assess two-dimensional contents, is no longer applicable. It is necessary to give consideration to depth when evaluating 3D visual experience. Although 3D scenes enhance the overall subjective performance such as naturalness and presence, the health issues and stereoscopic distortion related to the introduction of depth cannot be ignored.

Subjective evaluation of stereoscopic image quality

Stereoscopic/3D image and video quality assessment (IQA/VQA) has become increasing relevant in today's world, owing to the amount of attention that has recently been focused on 3D/stereoscopic cinema, television, gaming, and mobile video. Understanding the quality of experience of human viewers as they watch 3D videos is a complex and multi-disciplinary problem. Toward this end we offer a holistic assessment of the issues that are encountered, survey the progress that has been made towards addressing these issues, discuss ongoing efforts to resolve them, and point up the future challenges that need to be focused on. Important tools in the study of the quality of 3D visual signals are databases of 3D image and video sets, distorted versions of these signals and the results of large-scale studies of human opinions of their quality. We explain the construction of one such tool, the LIVE 3D IQA database, which is the first publicly available 3D IQA database that incorporates ‘true’ depth information along with stereoscopic pairs and human opinion scores. We describe the creation of the database and analyze the performance of a variety of 2D and 3D quality models using the new database. The database as well as the algorithms evaluated are available for researchers in the field to use in order to enable objective comparisons of future algorithms. Finally, we broadly summarize the field of 3D QA focusing on key unresolved problems including stereoscopic distortions, 3D masking, and algorithm development.

Incorrect depth sense due to focused object distance

In stereoscopy, stereoscopic depth distortion is a serious problem in terms of determining the correct depth sense. There have been few studies pertaining to the problem in terms of the focused object distance (FOD). In this investigation, we discuss the FOD as one of the factors inducing an incorrect depth sense in using common stereo camera systems and propose a method for compensating the incorrect depth sense, which is strongly related to the process of demagnifying the size of displayed stereo image on the screen. The incorrect depth sense increases when the FOD becomes shortened. Our method illustrates that the depth sense difference between a correct depth sense and an induced depth error is compensated completely. We verified the validation of our concerns by both a theoretical simulation and a practical experiment.

Optical compensation for two stereoscopic distortions

Abstract— A stereoscopic display configuration for presenting stereoscopic images without keystone and depth‐plane‐curvature distortions is proposed. The main idea of the proposed configuration is to perform optical compensation for these distortions by presenting left and right perspective images at two intersecting screens. The possibility of such distortion elimination was proven by two independent ways: analytically and graphically.

Stereoscopic image distortion in radial camera and projector configurations

A closed-form solution of describing perceived image in stereoscopic imaging systems with radial recording and projecting geometry for arbitrary viewer positions is presented. This solution is derived by finding a condition for making the heights of homolog points in both left and right images projected on the screen in the geometry equal. The solution has the same equation form as that of the parallel geometry except that it has a constant shifting term in the horizontal direction. This term is a main source for distortions in the perceived image. The condition of eliminating the term makes the solution the same as that for stereoscopic imaging systems with parallel recording and projecting geometry.

Effect of meridional disparity on depth perception

When a meridional-size lens is used to provide magnification in the horizonal meridan for one eye the resulting stereopsis distortion is readily accounted for in the terms of the binocular disparity caused by changed angular relations. When the same size lens is used to magnify the vertical meridian for one eye there is an opposite stereoscopic distortion for which is no ready geometric explanation. A perceptually induced mechanism operating in the vertical meridian has been suggested by Ogle. In the present experiment, apparatus was designed to introduce disparity of binocularly fused targets successively in each of several oblique meridians independent of the stereopsis measuring targets. Unlike the above-mentioned results obtained with size lenses, the induced stereoscopic distortion was in the same direction and of essentially the same magnitude for disparity in every meridian. It would follow that the perceptually induced mechanism is not exclusive to the vertical meridian.

STEREOSCOPIC DISTORTION AND STRUCTURALLY-IMPOSED RETINAL-IMAGE-SIZE-DIFFERENCES.

When the optical images formed on the two retinas differ in magnification (size), stereoscopically-based spatial distortions are expected to occur due to the ‘spurious’ binocular disparities generated. Whereas lens experiments bear out this expectation, it is not clear that distortion also accompanies the inherent image-size-differences that stem from structural differences between the two eyes. In the present study an attempt was made to compare the actual incidence of stereoscopic distortion in a given population with the expected incidence due to structurally-imposed image-size-differences. Stereoscopic distortion was measured on a space eikonometer. The expected incidence of stereoscopic distortion was computed from data reported in the ophthalmic literature. The results indicated a far lesser degree of distortion present than expected, thus suggesting that image-size-differences are somehow compensated when structurally imposed.

Incidence and Magnitude of Structurally Imposed Retinal Image Size Differences

Stereoscopic distortion results when retinal image size differences are induced by aniseikonic lenses. In the present study an attempt was made to determine with what frequency and magnitude retinal image size differences occur ‘naturally,’ on the basis of structural differences between the two eyes. An analysis of data from the opthalmologic literature was carried out. The results suggested that substantial retinal image-size-differences occur in the population studied. An adaptation hypothesis was briefly examined in an effort to account for the fact that instances of stereoscopic distortion are relatively infrequent.