An assessment model and implementation of stereo image quality

In the past decade, many display hardware manufacturers have initiated research into the construction of stereo display devices. Currently, the use of such displays is limited to the computer-aided design; research, military and medical applications. However, it is anticipated that as display hardware becomes cheaper, gaming companies and desktop application software developers will realise the potential of using stereo to provide more realistic user experiences. To provide realistic stereo user experience it is necessary to utilise good quality stereo images in addition to suitable hardware. The growth of the Internet has resulted in an increase in the availability of stereo images. However, most have been captured using uncontrolled procedures and have questionable quality. The quality of stereo images is important since the viewing of poor quality stereo images can result in adverse viewing effects. A formal definition of stereo quality has not been achieved in current day research. This means that the factors which cause a stereo image to be perceived as poor quality have not been defined nor is a system available to detect its occurrence. This thesis attempts to address this problem by postulating a definition of stereo image quality based on detecting level of excess disparity levels, intensity differences and the occurrence of frame cancellation. An implementation system able to detect these identified factors is discussed and formulated. The developed system is utilised to test 14 stereo images of varying quality levels. The results of these tests are reported and are used to evaluated and refine the system. Using this image analysis, benchmarks for natural intensity difference in images, changes due to JPEG compression and comparisons with generated and ground truth disparity maps are formulated. Additionally, a

Head Mounted Eye Tracking Aid for Central Visual Field Loss

University of Minnesota M.S.M.E. thesis. July 2016. Major: Mechanical Engineering. Advisor: Arthur Erdman. 1 computer file (PDF); viii, 137 pages.Age-Related Macular Degeneration results in central visual field loss (CFL) due to formation of central blind-spots or scotomas. Activities like reading are affected. We hypothesize that real-time remapping of lost information due to CFL onto a functional portion of the retina will improve visual performance. We have developed two hardware prototypes using a head-mounted display, integrated eye-tracker, and computer to remap and display images in real-time to the wearer. To test, in three different studies, normally-sighted subjects were asked to wear the head-mounted display with the built-in eye tracker. CFL was simulated by placing artificial circular scotomas ranging from 2° to 16° diameter over the gaze position, and reading speed was measured for the remapped and unremapped condition. We observed a statistically significant increase in mean reading speeds for the larger scotomas. Results indicate that the device shows promise for use with CFL patients

Spatial Displays and Spatial Instruments

The conference proceedings topics are divided into two main areas: (1) issues of spatial and picture perception raised by graphical electronic displays of spatial information; and (2) design questions raised by the practical experience of designers actually defining new spatial instruments for use in new aircraft and spacecraft. Each topic is considered from both a theoretical and an applied direction. Emphasis is placed on discussion of phenomena and determination of design principles

Perceived Depth Control in Stereoscopic Cinematography

Despite the recent explosion of interest in the stereoscopic 3D (S3D) technology, the ultimate prevailing of the S3D medium is still significantly hindered by adverse effects regarding the S3D viewing discomfort. This thesis attempts to improve the S3D viewing experience by investigating perceived depth control methods in stereoscopic cinematography on desktop 3D displays. The main contributions of this work are: (1) A new method was developed to carry out human factors studies on identifying the practical limits of the 3D Comfort Zone on a given 3D display. Our results suggest that it is necessary for cinematographers to identify the specific limits of 3D Comfort Zone on the target 3D display as different 3D systems have different ranges for the 3D Comfort Zone. (2) A new dynamic depth mapping approach was proposed to improve the depth perception in stereoscopic cinematography. The results of a human-based experiment confirmed its advantages in controlling the perceived depth in viewing 3D motion pictures over the existing depth mapping methods. (3) The practicability of employing the Depth of Field (DoF) blur technique in S3D was also investigated. Our results indicate that applying the DoF blur simulation on stereoscopic content may not improve the S3D viewing experience without the real time information about what the viewer is looking at. Finally, a basic guideline for stereoscopic cinematography was introduced to summarise the new findings of this thesis alongside several well-known key factors in 3D cinematography. It is our assumption that this guideline will be of particular interest not only to 3D filmmaking but also to 3D gaming, sports broadcasting, and TV production

Computer vision

The field of computer vision is surveyed and assessed, key research issues are identified, and possibilities for a future vision system are discussed. The problems of descriptions of two and three dimensional worlds are discussed. The representation of such features as texture, edges, curves, and corners are detailed. Recognition methods are described in which cross correlation coefficients are maximized or numerical values for a set of features are measured. Object tracking is discussed in terms of the robust matching algorithms that must be devised. Stereo vision, camera control and calibration, and the hardware and systems architecture are discussed

Oculomotor responses and 3D displays

This thesis investigated some of the eye movement factors related to the development and use of eye pointing devices with three dimensional displays (stereoscopic and linear perspective). In order for eye pointing to be used as a successful device for input-control of a 3D display it is necessary to characterise the accuracy and speed with which the binocular point of foveation can locate a particular point in 3D space. Linear perspective was found to be insufficient to elicit a change in the depth of the binocular point of fixation except under optimal conditions (monocular viewing, accommodative loop open and constant display paradigm). Comparison of the oculomotor responses made between a stereoscopic 'virtual' and a 'real' display showed there were no differences with regards to target fixational accuracy. With one exception, subjects showed the same degree of fixational accuracy with respect to target direction and depth. However, close target proximity (in terms of direction) affected the accuracy of fixation with respect to depth (but not direction). No differences were found between fixational accuracy of large and small targets under either display conditions. The visual conditions eliciting fast changes in the location of the binocular point of foveation, i.e. saccade disconjugacy, were investigated. Target-directed saccade disconjugacy was confirmed, in some cases, between targets presented at different depths on a stereoscopic display. However, in general the direction of saccade disconjugacy was best predicted by the horizontal direction of the target. Leftward saccade disconjugacy was more divergent than rightward. This asymmetry was overlaid on a disconjugacy response, which when considered in relative terms, was appropriated for the level of vergence demand. Linear perspective depth cues did not elicit target-directed disconjugate saccades

Foveation for 3D visualization and stereo imaging

Even though computer vision and digital photogrammetry share a number of goals, techniques, and methods, the potential for cooperation between these fields is not fully exploited. In attempt to help bridging the two, this work brings a well-known computer vision and image processing technique called foveation and introduces it to photogrammetry, creating a hybrid application. The results may be beneficial for both fields, plus the general stereo imaging community, and virtual reality applications. Foveation is a biologically motivated image compression method that is often used for transmitting videos and images over networks. It is possible to view foveation as an area of interest management method as well as a compression technique. While the most common foveation applications are in 2D there are a number of binocular approaches as well. For this research, the current state of the art in the literature on level of detail, human visual system, stereoscopic perception, stereoscopic displays, 2D and 3D foveation, and digital photogrammetry were reviewed. After the review, a stereo-foveation model was constructed and an implementation was realized to demonstrate a proof of concept. The conceptual approach is treated as generic, while the implementation was conducted under certain limitations, which are documented in the relevant context. A stand-alone program called Foveaglyph is created in the implementation process. Foveaglyph takes a stereo pair as input and uses an image matching algorithm to find the parallax values. It then calculates the 3D coordinates for each pixel from the geometric relationships between the object and the camera configuration or via a parallax function. Once 3D coordinates are obtained, a 3D image pyramid is created. Then, using a distance dependent level of detail function, spherical volume rings with varying resolutions throughout the 3D space are created. The user determines the area of interest. The result of the application is a user controlled, highly compressed non-uniform 3D anaglyph image. 2D foveation is also provided as an option. This type of development in a photogrammetric visualization unit is beneficial for system performance. The research is particularly relevant for large displays and head mounted displays. Although, the implementation, because it is done for a single user, would possibly be best suited to a head mounted display (HMD) application. The resulting stereo-foveated image can be loaded moderately faster than the uniform original. Therefore, the program can potentially be adapted to an active vision system and manage the scene as the user glances around, given that an eye tracker determines where exactly the eyes accommodate. This exploration may also be extended to robotics and other robot vision applications. Additionally, it can also be used for attention management and the viewer can be directed to the object(s) of interest the demonstrator would like to present (e.g. in 3D cinema). Based on the literature, we also believe this approach should help resolve several problems associated with stereoscopic displays such as the accommodation convergence problem and diplopia. While the available literature provides some empirical evidence to support the usability and benefits of stereo foveation, further tests are needed. User surveys related to the human factors in using stereo foveated images, such as its possible contribution to prevent user discomfort and virtual simulator sickness (VSS) in virtual environments, are left as future work.reviewe