Methods for reducing visual discomfort in stereoscopic 3D: A review

This work was supported by the EPSRC Grant EP/M01469X/1, “Geometric Evaluation of Stereoscopic Video”

3D Multi-user interactive visualization with a shared large-scale display

When the multiple users interact with a virtual environment on a largescale display there are several issues that need to be addressed to facilitate the interaction. In the thesis, three main topics for collaborative visualization are discussed; display setup, interactive visualization, and visual fatigue. The problems that the author is trying to address in this thesis are how multiple users can interact with a shared large-scale display depending on the display setups and how they can interact with the shared visualization in a way that doesn’t lead to visual fatigue. The first user study (Chapter 3) explores the display setups for multi-user interaction with a shared large-display. The author describes the design of the three main display setups (a shared view, a split screen, and a split screen with navigation information) and a demonstration using these setups. The user study found that the split screen and the split screen with navigation information can improve users’ confidence and reduce frustration level and are more preferred than a shared view. However, a shared view can still provide effective interaction and collaboration and the display setups cannot have a large impact on usability and workload. From the first study, the author employed a shared view for multi-user interactive visualization with a shared large-scale display due to the advantages of the shared view. To improve interactive visualization with a shared view for multiple users, the author designed and conducted the second user study (Chapter 4). A conventional interaction technique, the mean tracking method, was not effective for more than three users. In order to overcome the limitation of the current multi-user interactive visualization techniques, two interactive visualization techniques (the Object Shift Technique and Activity-based Weighted Mean Tracking method) were developed and were evaluated in the second user study. The Object Shift Technique translates the virtual objects in the opposite direction of movement of the Point of View (PoV) and the Activity-based Weighted Mean Tracking method assigns the higher weight to active users in comparison with stationary users to determine the location of the PoV. The results of the user study showed that these techniques can support collaboration, improve interactivity, and provide similar visual discomfort compared to the conventional method. The third study (Chapter 5) describes how to reduce visual fatigue for 3D stereoscopic visualization with a single point of view (PoV). When multiple users interact with 3D stereoscopic VR using multi-user interactive visualization techniques and they are close to the virtual objects, they can perceive 3D visual fatigue from the large disparity. To reduce the 3D visual fatigue, an Adaptive Interpupillary Distance (Adaptive IPD) adjustment technique was developed. To evaluate the Adaptive IPD method, the author compared to traditional 3D stereoscopic and the monoscopic visualization techniques. Through the user experiments, the author was able to confirm that the proposed method can reduce visual discomfort, yet maintain compelling depth perception as the result provided the most preferable 3D stereoscopic visualization experience. For these studies, the author developed a software framework and designed a set of experiments (Chapter 6). The framework architecture that contains the three main ideas are described. A demonstration application for multidimensional decision making was developed using the framework. The primary contributions of this thesis include a literature review of multiuser interaction with a shared large-scale display, deeper insights into three display setups for multi-user interaction, development of the Object Shift Techniques, the Activity-based Weighted Mean Tracking method, and the Adaptive Interpupillary Distance Adjustment technique, the evaluation of the three novel interaction techniques, development of a framework for supporting a multi-user interaction with a shared large-scale display and its application to multi-dimensional decision making VR system

3-D Interfaces for Spatial Construction

It is becoming increasingly easy to bring the body directly to digital form via stereoscopic immersive displays and tracked input devices. Is this space a viable one in which to construct 3d objects? Interfaces built upon two-dimensional displays and 2d input devices are the current standard for spatial construction, yet 3d interfaces, where the dimensionality of the interactive space matches that of the design space, have something unique to offer. This work increases the richness of 3d interfaces by bringing several new tools into the picture: the hand is used directly to trace surfaces; tangible tongs grab, stretch, and rotate shapes; a handle becomes a lightsaber and a tool for dropping simple objects; and a raygun, analagous to the mouse, is used to select distant things. With these tools, a richer 3d interface is constructed in which a variety of objects are created by novice users with relative ease. What we see is a space, not exactly like the traditional 2d computer, but rather one in which a distinct and different set of operations is easy and natural. Design studies, complemented by user studies, explore the larger space of three-dimensional input possibilities. The target applications are spatial arrangement, freeform shape construction, and molecular design. New possibilities for spatial construction develop alongside particular nuances of input devices and the interactions they support. Task-specific tangible controllers provide a cultural affordance which links input devices to deep histories of tool use, enhancing intuition and affective connection within an interface. On a more practical, but still emotional level, these input devices frame kinesthetic space, resulting in high-bandwidth interactions where large amounts of data can be comfortably and quickly communicated. A crucial issue with this interface approach is the tension between specific and generic input devices. Generic devices are the tradition in computing -- versatile, remappable, frequently bereft of culture or relevance to the task at hand. Specific interfaces are an emerging trend -- customized, culturally rich, to date these systems have been tightly linked to a single application, limiting their widespread use. The theoretical heart of this thesis, and its chief contribution to interface research at large is an approach to customization. Instead of matching an application domain's data, each new input device supports a functional class. The spatial construction task is split into four types of manipulation: grabbing, pointing, holding, and rubbing. Each of these action classes spans the space of spatial construction, allowing a single tool to be used in many settings without losing the unique strengths of its specific form. Outside of 3d interface, outside of spatial construction, this approach strikes a balance between generic and specific suitable for many interface scenarios. In practice, these specific function groups are given versatility via a quick remapping technique which allows one physical tool to perform many digital tasks. For example, the handle can be quickly remapped from a lightsaber that cuts shapes to tools that place simple platonic solids, erase portions of objects, and draw double-helices in space. The contributions of this work lie both in a theoretical model of spatial interaction, and input devices (combined with new interactions) which illustrate the efficacy of this philosophy. This research brings the new results of Tangible User Interface to the field of Virtual Reality. We find a space, in and around the hand, where full-fledged haptics are not necessary for users physically connect with digital form.</p

Remote Visual Observation of Real Places Through Virtual Reality Headsets

Virtual Reality has always represented a fascinating yet powerful opportunity that has attracted studies and technology developments, especially since the latest release on the market of powerful high-resolution and wide field-of-view VR headsets. While the great potential of such VR systems is common and accepted knowledge, issues remain related to how to design systems and setups capable of fully exploiting the latest hardware advances. The aim of the proposed research is to study and understand how to increase the perceived level of realism and sense of presence when remotely observing real places through VR headset displays. Hence, to produce a set of guidelines that give directions to system designers about how to optimize the display-camera setup to enhance performance, focusing on remote visual observation of real places. The outcome of this investigation represents unique knowledge that is believed to be very beneficial for better VR headset designs towards improved remote observation systems. To achieve the proposed goal, this thesis presents a thorough investigation of existing literature and previous researches, which is carried out systematically to identify the most important factors ruling realism, depth perception, comfort, and sense of presence in VR headset observation. Once identified, these factors are further discussed and assessed through a series of experiments and usability studies, based on a predefined set of research questions. More specifically, the role of familiarity with the observed place, the role of the environment characteristics shown to the viewer, and the role of the display used for the remote observation of the virtual environment are further investigated. To gain more insights, two usability studies are proposed with the aim of defining guidelines and best practices. The main outcomes from the two studies demonstrate that test users can experience an enhanced realistic observation when natural features, higher resolution displays, natural illumination, and high image contrast are used in Mobile VR. In terms of comfort, simple scene layouts and relaxing environments are considered ideal to reduce visual fatigue and eye strain. Furthermore, sense of presence increases when observed environments induce strong emotions, and depth perception improves in VR when several monocular cues such as lights and shadows are combined with binocular depth cues. Based on these results, this investigation then presents a focused evaluation on the outcomes and introduces an innovative eye-adapted High Dynamic Range (HDR) approach, which the author believes to be of great improvement in the context of remote observation when combined with eye-tracked VR headsets. Within this purpose, a third user study is proposed to compare static HDR and eye-adapted HDR observation in VR, to assess that the latter can improve realism, depth perception, sense of presence, and in certain cases even comfort. Results from this last study confirmed the author expectations, proving that eye-adapted HDR and eye tracking should be used to achieve best visual performances for remote observation in modern VR systems

TractorEYE: Vision-based Real-time Detection for Autonomous Vehicles in Agriculture

Agricultural vehicles such as tractors and harvesters have for decades been able to navigate automatically and more efficiently using commercially available products such as auto-steering and tractor-guidance systems. However, a human operator is still required inside the vehicle to ensure the safety of vehicle and especially surroundings such as humans and animals. To get fully autonomous vehicles certified for farming, computer vision algorithms and sensor technologies must detect obstacles with equivalent or better than human-level performance. Furthermore, detections must run in real-time to allow vehicles to actuate and avoid collision.This thesis proposes a detection system (TractorEYE), a dataset (FieldSAFE), and procedures to fuse information from multiple sensor technologies to improve detection of obstacles and to generate a map. TractorEYE is a multi-sensor detection system for autonomous vehicles in agriculture. The multi-sensor system consists of three hardware synchronized and registered sensors (stereo camera, thermal camera and multi-beam lidar) mounted on/in a ruggedized and water-resistant casing. Algorithms have been developed to run a total of six detection algorithms (four for rgb camera, one for thermal camera and one for a Multi-beam lidar) and fuse detection information in a common format using either 3D positions or Inverse Sensor Models. A GPU powered computational platform is able to run detection algorithms online. For the rgb camera, a deep learning algorithm is proposed DeepAnomaly to perform real-time anomaly detection of distant, heavy occluded and unknown obstacles in agriculture. DeepAnomaly is -- compared to a state-of-the-art object detector Faster R-CNN -- for an agricultural use-case able to detect humans better and at longer ranges (45-90m) using a smaller memory footprint and 7.3-times faster processing. Low memory footprint and fast processing makes DeepAnomaly suitable for real-time applications running on an embedded GPU. FieldSAFE is a multi-modal dataset for detection of static and moving obstacles in agriculture. The dataset includes synchronized recordings from a rgb camera, stereo camera, thermal camera, 360-degree camera, lidar and radar. Precise localization and pose is provided using IMU and GPS. Ground truth of static and moving obstacles (humans, mannequin dolls, barrels, buildings, vehicles, and vegetation) are available as an annotated orthophoto and GPS coordinates for moving obstacles. Detection information from multiple detection algorithms and sensors are fused into a map using Inverse Sensor Models and occupancy grid maps. This thesis presented many scientific contribution and state-of-the-art within perception for autonomous tractors; this includes a dataset, sensor platform, detection algorithms and procedures to perform multi-sensor fusion. Furthermore, important engineering contributions to autonomous farming vehicles are presented such as easily applicable, open-source software packages and algorithms that have been demonstrated in an end-to-end real-time detection system. The contributions of this thesis have demonstrated, addressed and solved critical issues to utilize camera-based perception systems that are essential to make autonomous vehicles in agriculture a reality

Enhancing Virtual City with Collective Memory to Support Urban Design Learning

This research investigates the pedagogical effects of collective memory enhanced virtual city models as an e-learning environment for urban design in an Indonesian university context. In this study, collective memory refers to expressions people made when remembering buildings, spaces and places of the past and present city living. A city's collective memory is either elicited from or produced directly by the city's residents or visitors. The thesis presents the outcomes of designing an experimental collective memory enhanced virtual city (CREATI) platform and applying it to the urban design course at the Department of Architecture, Atma Jaya Yogyakarta University, Indonesia. The Jalan Malioboro area in Yogyakarta was chosen as the case study site for constructing 30 virtual city models and gathering records of collective memory associated with the street and city. Student participants were invited to use CREATI while undertaking the urban design course. The usability and effects of CREATI on the students' learning outcomes are analysed according to the learning experiences reported by the students as well as the urban design proposals they produced for the course. The study finds that students appear more knowledgeable about the urban contextual issues because of accessing and sharing the resources hosted on CREATI. Students also reported that they felt better supported in developing more context­ sensitive design proposals by working with the collective memory enhanced virtual city models

Compression and Subjective Quality Assessment of 3D Video

In recent years, three-dimensional television (3D TV) has been broadly considered as the successor to the existing traditional two-dimensional television (2D TV) sets. With its capability of offering a dynamic and immersive experience, 3D video (3DV) is expected to expand conventional video in several applications in the near future. However, 3D content requires more than a single view to deliver the depth sensation to the viewers and this, inevitably, increases the bitrate compared to the corresponding 2D content. This need drives the research trend in video compression field towards more advanced and more efficient algorithms. Currently, the Advanced Video Coding (H.264/AVC) is the state-of-the-art video coding standard which has been developed by the Joint Video Team of ISO/IEC MPEG and ITU-T VCEG. This codec has been widely adopted in various applications and products such as TV broadcasting, video conferencing, mobile TV, and blue-ray disc. One important extension of H.264/AVC, namely Multiview Video Coding (MVC) was an attempt to multiple view compression by taking into consideration the inter-view dependency between different views of the same scene. This codec H.264/AVC with its MVC extension (H.264/MVC) can be used for encoding either conventional stereoscopic video, including only two views, or multiview video, including more than two views. In spite of the high performance of H.264/MVC, a typical multiview video sequence requires a huge amount of storage space, which is proportional to the number of offered views. The available views are still limited and the research has been devoted to synthesizing an arbitrary number of views using the multiview video and depth map (MVD). This process is mandatory for auto-stereoscopic displays (ASDs) where many views are required at the viewer side and there is no way to transmit such a relatively huge number of views with currently available broadcasting technology. Therefore, to satisfy the growing hunger for 3D related applications, it is mandatory to further decrease the bitstream by introducing new and more efficient algorithms for compressing multiview video and depth maps. This thesis tackles the 3D content compression targeting different formats i.e. stereoscopic video and depth-enhanced multiview video. Stereoscopic video compression algorithms introduced in this thesis mostly focus on proposing different types of asymmetry between the left and right views. This means reducing the quality of one view compared to the other view aiming to achieve a better subjective quality against the symmetric case (the reference) and under the same bitrate constraint. The proposed algorithms to optimize depth-enhanced multiview video compression include both texture compression schemes as well as depth map coding tools. Some of the introduced coding schemes proposed for this format include asymmetric quality between the views. Knowing that objective metrics are not able to accurately estimate the subjective quality of stereoscopic content, it is suggested to perform subjective quality assessment to evaluate different codecs. Moreover, when the concept of asymmetry is introduced, the Human Visual System (HVS) performs a fusion process which is not completely understood. Therefore, another important aspect of this thesis is conducting several subjective tests and reporting the subjective ratings to evaluate the perceived quality of the proposed coded content against the references. Statistical analysis is carried out in the thesis to assess the validity of the subjective ratings and determine the best performing test cases

Courts Without Court

What role does the physical courthouse play in the administration of criminal justice? This Article uses recent experiments with virtual courts to reimagine a future without criminal courthouses at the center. The key insight of this Article is to reveal how integral physical courts are to carceral control and how the rise of virtual courts helps to decenter power away from judges. This Article examines the effects of online courts on defendants, lawyers, judges, witnesses, victims, and courthouse officials and offers a framework for a better and less court-centered future. By studying post-COVID-19 disruptions around traditional conceptions of place, time, equality, accountability, and trial practice, this Article identifies how legal power can be shifted away from the courts and into the community

3D panoramic imaging for virtual environment construction

The project is concerned with the development of algorithms for the creation of photo-realistic 3D virtual environments, overcoming problems in mosaicing, colour and lighting changes, correspondence search speed and correspondence errors due to lack of surface texture. A number of related new algorithms have been investigated for image stitching, content based colour correction and efficient 3D surface reconstruction. All of the investigations were undertaken by using multiple views from normal digital cameras, web cameras and a ”one-shot” panoramic system. In the process of 3D reconstruction a new interest points based mosaicing method, a new interest points based colour correction method, a new hybrid feature and area based correspondence constraint and a new structured light based 3D reconstruction method have been investigated. The major contributions and results can be summarised as follows: • A new interest point based image stitching method has been proposed and investigated. The robustness of interest points has been tested and evaluated. Interest points have been proved robust to changes in lighting, viewpoint, rotation and scale. • A new interest point based method for colour correction has been proposed and investigated. The results of linear and linear plus affine colour transforms have proved more accurate than traditional diagonal transforms in accurately matching colours in panoramic images. • A new structured light based method for correspondence point based 3D reconstruction has been proposed and investigated. The method has been proved to increase the accuracy of the correspondence search for areas with low texture. Correspondence speed has also been increased with a new hybrid feature and area based correspondence search constraint. • Based on the investigation, a software framework has been developed for image based 3D virtual environment construction. The GUI includes abilities for importing images, colour correction, mosaicing, 3D surface reconstruction, texture recovery and visualisation. • 11 research papers have been published.EThOS - Electronic Theses Online ServiceGBUnited Kingdo