Improving visual quality of view transitions in automultiscopic displays

Automultiscopic screens present different images depending on the viewing direction. This enables glasses-free 3D and provides motion parallax effect. However, due to the limited angular resolution of such displays, they suffer from hot-spotting, i. e., image quality is highly affected by the viewing position. In this paper, we analyze light fields produced by lenticular and parallax-barrier displays, and show that, unlike in real world, the light fields produced by such screens have a repetitive structure. This induces visual artifacts in the form of view discontinuities, depth reversals, and excessive disparities when viewing position is not optimal. Although the problem has been always considered as inherent to the technology, we demonstrate that light fields reproduced on automultiscopic displays have enough degrees of freedom to improve the visual quality. We propose a new technique that modifies light fields using global and local shears followed by stitching to improve their continuity when displayed on a screen. We show that this enhances visual quality significantly, which is demonstrated in a series of user experiments with an automultiscopic display as well as lenticular prints.National Science Foundation (U.S.) (IIS-1111415)National Science Foundation (U.S.) (IIS-1116296)Quanta Computer (Firm)National Basic Research Program of China (973 Program) (Project 2011CB302205)National Natural Science Foundation (China) (Project 61272226/61120106007)National High-Tech R&D (863) Plan of China (Project 2013AA013903)Beijing Higher Institution Engineering Research Center (Research Grant

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”

Magnetically Activated Stereoscopic Vision System for Laparoendoscopic Single-Site Surgery

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Light field image processing: an overview

Light field imaging has emerged as a technology allowing to capture richer visual information from our world. As opposed to traditional photography, which captures a 2D projection of the light in the scene integrating the angular domain, light fields collect radiance from rays in all directions, demultiplexing the angular information lost in conventional photography. On the one hand, this higher dimensional representation of visual data offers powerful capabilities for scene understanding, and substantially improves the performance of traditional computer vision problems such as depth sensing, post-capture refocusing, segmentation, video stabilization, material classification, etc. On the other hand, the high-dimensionality of light fields also brings up new challenges in terms of data capture, data compression, content editing, and display. Taking these two elements together, research in light field image processing has become increasingly popular in the computer vision, computer graphics, and signal processing communities. In this paper, we present a comprehensive overview and discussion of research in this field over the past 20 years. We focus on all aspects of light field image processing, including basic light field representation and theory, acquisition, super-resolution, depth estimation, compression, editing, processing algorithms for light field display, and computer vision applications of light field data

Stereoscopic 3D Technologies for Accurate Depth Tasks: A Theoretical and Empirical Study

In the last decade an increasing number of application fields, including medicine, geoscience and bio-chemistry, have expressed a need to visualise and interact with data that are inherently three-dimensional. Stereoscopic 3D technologies can offer a valid support for these operations thanks to the enhanced depth representation they can provide. However, there is still little understanding of how such technologies can be used effectively to support the performance of visual tasks based on accurate depth judgements. Existing studies do not provide a sound and complete explanation of the impact of different visual and technical factors on depth perception in stereoscopic 3D environments. This thesis presents a new interpretative and contextualised analysis of the vision science literature to clarify the role of di®erent visual cues on human depth perception in such environments. The analysis identifies luminance contrast, spatial frequency, colour, blur, transparency and depth constancies as influential visual factors for depth perception and provides the theoretical foundation for guidelines to support the performance of accurate stereoscopic depth tasks. A novel assessment framework is proposed and used to conduct an empirical study to evaluate the performance of four distinct classes of 3D display technologies. The results suggest that 3D displays are not interchangeable and that the depth representation provided can vary even between displays belonging to the same class. The study also shows that interleaved displays may suffer from a number of aliasing artifacts, which in turn may affect the amount of perceived depth. The outcomes of the analysis of the influential visual factors for depth perception and the empirical comparartive study are used to propose a novel universal 3D cursor prototype suitable to support depth-based tasks in stereoscopic 3D environments. The contribution includes a number of both qualitative and quantitative guidelines that aim to guarantee a correct perception of depth in stereoscopic 3D environments and that should be observed when designing a stereoscopic 3D cursor

Rendering and display for multi-viewer tele-immersion

Video teleconferencing systems are widely deployed for business, education and personal use to enable face-to-face communication between people at distant sites. Unfortunately, the two-dimensional video of conventional systems does not correctly convey several important non-verbal communication cues such as eye contact and gaze awareness. Tele-immersion refers to technologies aimed at providing distant users with a more compelling sense of remote presence than conventional video teleconferencing. This dissertation is concerned with the particular challenges of interaction between groups of users at remote sites. The problems of video teleconferencing are exacerbated when groups of people communicate. Ideally, a group tele-immersion system would display views of the remote site at the right size and location, from the correct viewpoint for each local user. However, is is not practical to put a camera in every possible eye location, and it is not clear how to provide each viewer with correct and unique imagery. I introduce rendering techniques and multi-view display designs to support eye contact and gaze awareness between groups of viewers at two distant sites. With a shared 2D display, virtual camera views can improve local spatial cues while preserving scene continuity, by rendering the scene from novel viewpoints that may not correspond to a physical camera. I describe several techniques, including a compact light field, a plane sweeping algorithm, a depth dependent camera model, and video-quality proxies, suitable for producing useful views of a remote scene for a group local viewers. The first novel display provides simultaneous, unique monoscopic views to several users, with fewer user position restrictions than existing autostereoscopic displays. The second is a random hole barrier autostereoscopic display that eliminates the viewing zones and user position requirements of conventional autostereoscopic displays, and provides unique 3D views for multiple users in arbitrary locations

Motion parallax for 360° RGBD video

We present a method for adding parallax and real-time playback of 360° videos in Virtual Reality headsets. In current video players, the playback does not respond to translational head movement, which reduces the feeling of immersion, and causes motion sickness for some viewers. Given a 360° video and its corresponding depth (provided by current stereo 360° stitching algorithms), a naive image-based rendering approach would use the depth to generate a 3D mesh around the viewer, then translate it appropriately as the viewer moves their head. However, this approach breaks at depth discontinuities, showing visible distortions, whereas cutting the mesh at such discontinuities leads to ragged silhouettes and holes at disocclusions. We address these issues by improving the given initial depth map to yield cleaner, more natural silhouettes. We rely on a three-layer scene representation, made up of a foreground layer and two static background layers, to handle disocclusions by propagating information from multiple frames for the first background layer, and then inpainting for the second one. Our system works with input from many of today''s most popular 360° stereo capture devices (e.g., Yi Halo or GoPro Odyssey), and works well even if the original video does not provide depth information. Our user studies confirm that our method provides a more compelling viewing experience than without parallax, increasing immersion while reducing discomfort and nausea

Extending mobile touchscreen interaction

Touchscreens have become a de facto interface for mobile devices, and are penetrating further beyond their core application domain of smartphones. This work presents a design space for extending touchscreen interaction, to which new solutions may be mapped. Specific touchscreen enhancements in the domains of manual input, visual output and haptic feedback are explored and quantitative and experiental findings reported. Particular areas covered are unintentional interaction, screen locking, stereoscopic displays and picoprojection. In addition, the novel interaction approaches of finger identification and onscreen physical guides are also explored. The use of touchscreens in the domains of car dashboards and smart handbags are evaluated as domain specific use cases. This work draws together solutions from the broad area of mobile touchscreen interaction. Fruitful directions for future research are identified, and information is provided for future researchers addressing those topics.Kosketusnäytöistä on muodostunut mobiililaitteiden pääasiallinen käyttöliittymä, ja ne ovat levinneet alkuperäiseltä ydinsovellusalueeltaan, matkapuhelimista, myös muihin laitteisiin. Työssä tutkitaan uusia vuorovaikutuksen, visualisoinnin ja käyttöliittymäpalautteen keinoja, jotka laajentavat perinteistä kosketusnäytön avulla tapahtuvaa vuorovaikutusta. Näihin liittyen väitöskirjassa esitetään sekä kvantitatiivisia tuloksia että uutta kartoittavia löydöksiä. Erityisesti työ tarkastelee tahatonta kosketusnäytön käyttöä, kosketusnäytön lukitusta, stereoskooppisia kosketusnäyttöjä ja pikoprojektoreiden hyödyntämistä. Lisäksi kartoitetaan uusia vuorovaikutustapoja, jotka liittyvät sormien identifioimiseen vuorovaikutuksen yhteydessä, ja fyysisiin, liikettä ohjaaviin rakenteisiin kosketusnäytöllä. Kosketusnäytön käyttöä autossa sekä osana älykästä käsilaukkua tarkastellaan esimerkkeinä käyttökonteksteista. Väitöskirjassa esitetään vuorovaikutussuunnittelun viitekehys, joka laajentaa kosketusnäyttöjen kautta tapahtuvaa vuorovaikutusta mobiililaitteen kanssa, ja johon työssä esitellyt, uudet vuorovaikutustavat voidaan sijoittaa. Väitöskirja yhdistää kosketusnäyttöihin liittyviä käyttöliittymäsuunnittelun ratkaisuja laajalta alueelta. Työ esittelee potentiaalisia suuntaviivoja tulevaisuuden tutkimuksille ja tuo uutta tutkimustietoa, jota mobiililaitteiden vuorovaikutuksen tutkijat ja käyttöliittymäsuunnittelijat voivat hyödyntää