NAMA3DS1-COSPAD1: Subjective video quality assessment database on coding conditions introducing freely available high quality 3D stereoscopic sequences

Research in stereoscopic 3D coding, transmission and subjective assessment methodology depends largely on the availability of source content that can be used in cross-lab evaluations. While several studies have already been presented using proprietary content, comparisons between the studies are difficult since discrepant contents are used. Therefore in this paper, a freely available dataset of high quality Full-HD stereoscopic sequences shot with a semiprofessional 3D camera is introduced in detail. The content was designed to be suited for usage in a wide variety of applications, including high quality studies. A set of depth maps was calculated from the stereoscopic pair. As an application example, a subjective assessment has been performed using coding and spatial degradations. The Absolute Category Rating with Hidden Reference method was used. The observers were instructed to vote on video quality only. Results of this experiment are also freely available and will be presented in this paper as a first step towards objective video quality measurement for 3DTV.

Visual attention and perception models for assessing quality in 2D and 3D stereoscopic video

La medida de calidad de vídeo sigue siendo necesaria para definir los criterios que caracterizan una señal que cumpla los requisitos de visionado impuestos por el usuario. Las nuevas tecnologías, como el vídeo 3D estereoscópico o formatos más allá de la alta definición, imponen nuevos criterios que deben ser analizadas para obtener la mayor satisfacción posible del usuario. Entre los problemas detectados durante el desarrollo de esta tesis doctoral se han determinado fenómenos que afectan a distintas fases de la cadena de producción audiovisual y tipo de contenido variado. En primer lugar, el proceso de generación de contenidos debe encontrarse controlado mediante parámetros que eviten que se produzca el disconfort visual y, consecuentemente, fatiga visual, especialmente en lo relativo a contenidos de 3D estereoscópico, tanto de animación como de acción real. Por otro lado, la medida de calidad relativa a la fase de compresión de vídeo emplea métricas que en ocasiones no se encuentran adaptadas a la percepción del usuario. El empleo de modelos psicovisuales y diagramas de atención visual permitirían ponderar las áreas de la imagen de manera que se preste mayor importancia a los píxeles que el usuario enfocará con mayor probabilidad. Estos dos bloques se relacionan a través de la definición del término saliencia. Saliencia es la capacidad del sistema visual para caracterizar una imagen visualizada ponderando las áreas que más atractivas resultan al ojo humano. La saliencia en generación de contenidos estereoscópicos se refiere principalmente a la profundidad simulada mediante la ilusión óptica, medida en términos de distancia del objeto virtual al ojo humano. Sin embargo, en vídeo bidimensional, la saliencia no se basa en la profundidad, sino en otros elementos adicionales, como el movimiento, el nivel de detalle, la posición de los píxeles o la aparición de caras, que serán los factores básicos que compondrán el modelo de atención visual desarrollado. Con el objetivo de detectar las características de una secuencia de vídeo estereoscópico que, con mayor probabilidad, pueden generar disconfort visual, se consultó la extensa literatura relativa a este tema y se realizaron unas pruebas subjetivas preliminares con usuarios. De esta forma, se llegó a la conclusión de que se producía disconfort en los casos en que se producía un cambio abrupto en la distribución de profundidades simuladas de la imagen, aparte de otras degradaciones como la denominada “violación de ventana”. A través de nuevas pruebas subjetivas centradas en analizar estos efectos con diferentes distribuciones de profundidades, se trataron de concretar los parámetros que definían esta imagen. Los resultados de las pruebas demuestran que los cambios abruptos en imágenes se producen en entornos con movimientos y disparidades negativas elevadas que producen interferencias en los procesos de acomodación y vergencia del ojo humano, así como una necesidad en el aumento de los tiempos de enfoque del cristalino. En la mejora de las métricas de calidad a través de modelos que se adaptan al sistema visual humano, se realizaron también pruebas subjetivas que ayudaron a determinar la importancia de cada uno de los factores a la hora de enmascarar una determinada degradación. Los resultados demuestran una ligera mejora en los resultados obtenidos al aplicar máscaras de ponderación y atención visual, los cuales aproximan los parámetros de calidad objetiva a la respuesta del ojo humano. ABSTRACT Video quality assessment is still a necessary tool for defining the criteria to characterize a signal with the viewing requirements imposed by the final user. New technologies, such as 3D stereoscopic video and formats of HD and beyond HD oblige to develop new analysis of video features for obtaining the highest user’s satisfaction. Among the problems detected during the process of this doctoral thesis, it has been determined that some phenomena affect to different phases in the audiovisual production chain, apart from the type of content. On first instance, the generation of contents process should be enough controlled through parameters that avoid the occurrence of visual discomfort in observer’s eye, and consequently, visual fatigue. It is especially necessary controlling sequences of stereoscopic 3D, with both animation and live-action contents. On the other hand, video quality assessment, related to compression processes, should be improved because some objective metrics are adapted to user’s perception. The use of psychovisual models and visual attention diagrams allow the weighting of image regions of interest, giving more importance to the areas which the user will focus most probably. These two work fields are related together through the definition of the term saliency. Saliency is the capacity of human visual system for characterizing an image, highlighting the areas which result more attractive to the human eye. Saliency in generation of 3DTV contents refers mainly to the simulated depth of the optic illusion, i.e. the distance from the virtual object to the human eye. On the other hand, saliency is not based on virtual depth, but on other features, such as motion, level of detail, position of pixels in the frame or face detection, which are the basic features that are part of the developed visual attention model, as demonstrated with tests. Extensive literature involving visual comfort assessment was looked up, and the development of new preliminary subjective assessment with users was performed, in order to detect the features that increase the probability of discomfort to occur. With this methodology, the conclusions drawn confirmed that one common source of visual discomfort was when an abrupt change of disparity happened in video transitions, apart from other degradations, such as window violation. New quality assessment was performed to quantify the distribution of disparities over different sequences. The results confirmed that abrupt changes in negative parallax environment produce accommodation-vergence mismatches derived from the increasing time for human crystalline to focus the virtual objects. On the other side, for developing metrics that adapt to human visual system, additional subjective tests were developed to determine the importance of each factor, which masks a concrete distortion. Results demonstrated slight improvement after applying visual attention to objective metrics. This process of weighing pixels approximates the quality results to human eye’s response.

Predatory vision : 3D imaging and the transformation of screen-space

Despite Wheatstone’s academic interests in the device, the stereoscope languished somewhat as an optical toy. Yet the advent of 3D screen-spaces for home and mass entertainment suggests today’s consumers and practitioners of screen culture hold the view that screen culture will be ‘improved’ through 3D imaging technologies. Like cinema and photography, stereoscopic 3D imaging has the potential to transform visual culture. But what is transformed, as optics and electronic imaging techniques deliver Alice in Wonderland in 3D? This paper links the advent of 3D cinema and TV to the notion that vision is itself a ‘technology of the visual’. As such, our innate binocular stereoacuity is ripe for exploitation by developers of 3D imaging technologies. I argue that contemporary 3D imaging marks an epistemological visual-perceptual shift: toward screenspaces becoming spaces for potential action. Such a shift entails seeing as doing rather than seeing as thinking. 3D imaging exploits binocular vision’s spatial acuity (stereopsis), but is effective only for objects within near distal space. The 3D effect tapers off dramatically for objects only some metres away, because the two retinal images lack significant lateral disparity (difference) to trigger stereopsis: the imagery flattens out and becomes ‘monoscopic’. Information available from conventional 2D media entails a peculiarly unspecified spatiality. Perceptually, the contents of a conventional cinematic screen are like those of a painting: they are situated neither near nor far, and constitute a shared and ambiguous visual space. Our own eyes are like those of a cat: frontally placed for predatory action. The visuality of 3D screen-spaces assumes a perceptuality of the near-by and close at hand, since this is the structure of the visible information to which stereopsis is adapted to respond. Noting the binocular acuity of predatory animals, as well as some etymological links, this paper examines the implications of perceptually ‘capturing’ the sensation of visually solid objects in one’s immediate space. Stereopsis is about decisive action within an immediate environment: but it also presupposes the single viewpoint of an active observer toward which the 3D imagery is targeted.

Adaptive protection scheme for MVC-encoded stereoscopic video streaming in IP-based networks

We present an adaptive unequal error protection (UEP) strategy built on the 1-D interleaved parity Application Layer Forward Error Correction (AL-FEC) code for protecting the transmission of stereoscopic 3D video content encoded with Multiview Video Coding (MVC) through IP-based networks. Our scheme targets the minimization of quality degradation produced by packet losses during video transmission in time-sensitive application scenarios. To that end, based on a novel packet-level distortion model, it selects in real time the most suitable packets within each Group of Pictures (GOP) to be protected and the most convenient FEC technique parameters, i.e., the size of the FEC generator matrix. In order to make these decisions, it considers the relevance of the packet, the behavior of the channel, and the available bitrate for protection purposes. Simulation results validate both the distortion model introduced to estimate the importance of packets and the optimization of the FEC technique parameter values.

Time for tea

Contemporary dance has only recently gained the capability of mapping imagery into 3D theatre environments that appear to move towards and away from the audiences. This capability radically expands the metaphoric content possible in dance work. This dance performance simply named “3D” combines contemporary dance with stereoscopic and video imagery. It was performed live within the Melbourne Fringe Festival at the No Vacancy Gallery at Federation Square from September 30 to October 2, 2011. The dance character is a Victorian woman living in a drought-stricken land who dreams of having enough water for a cup of tea. The stereoscopic (3d) images are metaphors for her hopes and dreams. It was performed and animated by Megan Beckwith and the sound design was by the international sound designer Jacques Soddell.

Time for tea

Contemporary dance has only recently gained the capability of mapping imagery into 3D theatre environments that appear to move towards and away from the audiences. This capability radically expands the metaphoric content possible in dance work. This dance performance simply named “3D” combines contemporary dance with stereoscopic and video imagery. The dance character is a Victorian woman living in a drought-stricken land who dreams of having enough water for a cup of tea. The stereoscopic (3d) images are metaphors for her hopes and dreams. It was performed and animated by Megan Beckwith and the sound design was by the international sound designer Jacques Soddell.

Vision, ambiguity and perceptual possibility : why pictures matter in the critique of stereo-immersive VR

The acquisition of three-dimensional immersive space through advanced digitial imaging technology, suggests a profound shift from the relatively impoverished representational stratgies of two-dimensional pictorial imagery.  This entails an epistemological shift from pictorial representation, to the presentation of actual three-dimensional space through stereoscopic (3D) imagery.  Moreover, it suggests that visuality rather than 'virtuality' is the core issue in understanding the nature of the epistemological shift associated with stereo-immersive VR.

A shift in visual epistemology from 'flat' pictorial representation to three-dimensional stereo-immersion suggests a gainful move toward a visuality imbued with spatial possibilities.  In quantitative terms, these visual-spatial gains may seem self-evident.  However, certain aspects peculiar to pictorial representation are missing from stereo-immersive imaging.  That is lost in stereo-immersive imaging, and how it can be measured?

This thesis proposes that the inherent ambiguity of two-dimensional representations of three-dimensional spatial structure in pictures, invokes a perceptual response in which pictorial spaces elicit 'perceptual possibility'.  The robust three-dimentional spatiality of stereo-immersvie VR foreclosures such possibility.  Through examining stereo-immersive VR in terms of its visuality, the thesis develops a new appraoch to understanding VR that solves some of the issues associated with the problematic concept of 'virtuality'.  In addition, the thesis finds that by placing stereo-immersive VR and pictures within the shared paradigm of 'the visual', an important dimension of pictures that has been overlooked in past analyses re-emerges : the thesis proposes the concept of 'artifactuality' to account for the way pictures are fundamentally, and in the first instance, aesthetic objects for visual perception.  It is in their manner of appearing as pictures, that they are perceived as pictures of something.  It is from this fundamental basis that their many levels of meaning and signification - their manifold 'realisms' - can arise.

This thesis therefore addresses two intersecting problems within the paradigm of the visual: it proposes 1) that analyses of 'the virtual' be grounded in the 'artifactuality' of pictorial perception, and 2) that the spatiality of stereo-immersive VR be reinvigorated by purposefully 'under-contraining' its key percept - the robust, 'solid' stereoscopic structuring of visual space.  This approach opens up the discourse of stereo-immersive VR to new visual paradigms.  The thesis proposes that these be modelled not on the impossibility of 'the virtual', but on the possibilities of visual ambiguity drawn from the analysis of pictorial perception.

Reproduction game demo

An 8 screen stereoscopic 3D Multi-user environment set in a circular formation. Paticipants are tracked by 8 kinect sensors as they move around the 360 degree installation. Participants inherit a species upon entering. Artificial Life based entities cluster towards the human particpants of their species and their songs evolve according to the interactions.

Digitale Einstrahl-Holographie atmosphärischer Eiskristalle

Es wurde ein für bodengebundene Feldmessungen geeignetes System zur digital-holographischen Abbildung luftgetragener Objekte entwickelt und konstruiert. Es ist, abhängig von der Tiefenposition, geeignet zur direkten Bestimmung der Größe luftgetragener Objekte oberhalb von ca. 20 µm, sowie ihrer Form bei Größen oberhalb von ca. 100µm bis in den Millimeterbereich. Die Entwicklung umfaßte zusätzlich einen Algorithmus zur automatisierten Verbesserung der Hologrammqualität und zur semiautomatischen Entfernungsbestimmung großer Objekte entwickelt. Eine Möglichkeit zur intrinsischen Effizienzsteigerung der Bestimmung der Tiefenposition durch die Berechnung winkelgemittelter Profile wurde vorgestellt. Es wurde weiterhin ein Verfahren entwickelt, das mithilfe eines iterativen Ansatzes für isolierte Objekte die Rückgewinnung der Phaseninformation und damit die Beseitigung des Zwillingsbildes erlaubt. Weiterhin wurden mithilfe von Simulationen die Auswirkungen verschiedener Beschränkungen der digitalen Holographie wie der endlichen Pixelgröße untersucht und diskutiert. Die geeignete Darstellung der dreidimensionalen Ortsinformation stellt in der digitalen Holographie ein besonderes Problem dar, da das dreidimensionale Lichtfeld nicht physikalisch rekonstruiert wird. Es wurde ein Verfahren entwickelt und implementiert, das durch Konstruktion einer stereoskopischen Repräsentation des numerisch rekonstruierten Meßvolumens eine quasi-dreidimensionale, vergrößerte Betrachtung erlaubt. Es wurden ausgewählte, während Feldversuchen auf dem Jungfraujoch aufgenommene digitale Hologramme rekonstruiert. Dabei ergab sich teilweise ein sehr hoher Anteil an irregulären Kristallformen, insbesondere infolge massiver Bereifung. Es wurden auch in Zeiträumen mit formal eisuntersättigten Bedingungen Objekte bis hinunter in den Bereich ≤20µm beobachtet. Weiterhin konnte in Anwendung der hier entwickelten Theorie des ”Phasenrandeffektes“ ein Objekt von nur ca. 40µm Größe als Eisplättchen identifiziert werden. Größter Nachteil digitaler Holographie gegenüber herkömmlichen photographisch abbildenden Verfahren ist die Notwendigkeit der aufwendigen numerischen Rekonstruktion. Es ergibt sich ein hoher rechnerischer Aufwand zum Erreichen eines einer Photographie vergleichbaren Ergebnisses. Andererseits weist die digitale Holographie Alleinstellungsmerkmale auf. Der Zugang zur dreidimensionalen Ortsinformation kann der lokalen Untersuchung der relativen Objektabstände dienen. Allerdings zeigte sich, dass die Gegebenheiten der digitalen Holographie die Beobachtung hinreichend großer Mengen von Objekten auf der Grundlage einzelner Hologramm gegenwärtig erschweren. Es wurde demonstriert, dass vollständige Objektgrenzen auch dann rekonstruiert werden konnten, wenn ein Objekt sich teilweise oder ganz außerhalb des geometrischen Meßvolumens befand. Weiterhin wurde die zunächst in Simulationen demonstrierte Sub-Bildelementrekonstruktion auf reale Hologramme angewandt. Dabei konnte gezeigt werden, dass z.T. quasi-punktförmige Objekte mit Sub-Pixelgenauigkeit lokalisiert, aber auch bei ausgedehnten Objekten zusätzliche Informationen gewonnen werden konnten. Schließlich wurden auf rekonstruierten Eiskristallen Interferenzmuster beobachtet und teilweise zeitlich verfolgt. Gegenwärtig erscheinen sowohl kristallinterne Reflexion als auch die Existenz einer (quasi-)flüssigen Schicht als Erklärung möglich, wobei teilweise in Richtung der letztgenannten Möglichkeit argumentiert werden konnte. Als Ergebnis der Arbeit steht jetzt ein System zur Verfügung, das ein neues Meßinstrument und umfangreiche Algorithmen umfaßt. S. M. F. Raupach, H.-J. Vössing, J. Curtius und S. Borrmann: Digital crossed-beam holography for in-situ imaging of atmospheric particles, J. Opt. A: Pure Appl. Opt. 8, 796-806 (2006) S. M. F. Raupach: A cascaded adaptive mask algorithm for twin image removal and its application to digital holograms of ice crystals, Appl. Opt. 48, 287-301 (2009) S. M. F. Raupach: Stereoscopic 3D visualization of particle fields reconstructed from digital inline holograms, (zur Veröffentlichung angenommen, Optik - Int. J. Light El. Optics, 2009)

Computational Tools for Stereo and Light Field Photography

This thesis covers a broad part of the field of computational photography, including video stabilization and image warping techniques, introductions to light field photography and the conversion of monocular images and videos into stereoscopic 3D content. We present a user assisted technique for stereoscopic 3D conversion from 2D images. Our approach exploits the geometric structure of perspective images including vanishing points. We allow a user to indicate lines, planes, and vanishing points in the input image, and directly employ these as guides of an image warp that produces a stereo image pair. Our method is most suitable for scenes with large scale structures such as buildings and is able to skip the step of constructing a depth map. Further, we propose a method to acquire 3D light fields using a hand-held camera, and describe several computational photography applications facilitated by our approach. As the input we take an image sequence from a camera translating along an approximately linear path with limited camera rotations. Users can acquire such data easily in a few seconds by moving a hand-held camera. We convert the input into a regularly sampled 3D light field by resampling and aligning them in the spatio-temporal domain. We also present a novel technique for high-quality disparity estimation from light fields. Finally, we show applications including digital refocusing and synthetic aperture blur, foreground removal, selective colorization, and others.

Automatic 3DTV Quality Assessment Based On Depth Perception Analysis

Quality assessment is a key factor for stereoscopic 3D video content as some observers are affected by visual discomfort in the eye when viewing 3D video, especially when combining positive and negative parallax with fast motion. In this paper, we propose techniques to assess objective quality related to motion and depth maps, which facilitate depth perception analysis. Subjective tests were carried out in order to understand the source of the problem. Motion is an important feature affecting 3D experience but also often the cause of visual discomfort. The automatic algorithm developed tries to quantify the impact on viewer experience when common cases of discomfort occur, such as high-motion sequences, scene changes with abrupt parallax changes, or complete absence of stereoscopy, with a goal of preventing the viewer from having a bad stereoscopic experience.

Aura, real-time motion capture dance and 3D stereoscopic dance

Aura explored the potential of motion capture and 3D stereo projection to visualize 1950's dance philosopher, Susanne K. Langer's notion of 'virtual force'.