Vision, Action, and Make-Perceive

In this paper, I critically assess the enactive account of visual perception recently defended by Alva Noë (2004). I argue inter alia that the enactive account falsely identifies an object’s apparent shape with its 2D perspectival shape; that it mistakenly assimilates visual shape perception and volumetric object recognition; and that it seriously misrepresents the constitutive role of bodily action in visual awareness. I argue further that noticing an object’s perspectival shape involves a hybrid experience combining both perceptual and imaginative elements – an act of what I call ‘make-perceive.

Occlusion-related lateral connections stabilize kinetic depth stimuli through perceptual coupling

Local sensory information is often ambiguous forcing the brain to integrate spatiotemporally separated information for stable conscious perception. Lateral connections between clusters of similarly tuned neurons in the visual cortex are a potential neural substrate for the coupling of spatially separated visual information. Ecological optics suggests that perceptual coupling of visual information is particularly beneficial in occlusion situations. Here we present a novel neural network model and a series of human psychophysical experiments that can together explain the perceptual coupling of kinetic depth stimuli with activity-driven lateral information sharing in the far depth plane. Our most striking finding is the perceptual coupling of an ambiguous kinetic depth cylinder with a coaxially presented and disparity defined cylinder backside, while a similar frontside fails to evoke coupling. Altogether, our findings are consistent with the idea that clusters of similarly tuned far depth neurons share spatially separated motion information in order to resolve local perceptual ambiguities. The classification of far depth in the facilitation mechanism results from a combination of absolute and relative depth that suggests a functional role of these lateral connections in the perception of partially occluded objects

Seamless and Secure VR: Adapting and Evaluating Established Authentication Systems for Virtual Reality

Virtual reality (VR) headsets are enabling a wide range of new opportunities for the user. For example, in the near future users may be able to visit virtual shopping malls and virtually join international conferences. These and many other scenarios pose new questions with regards to privacy and security, in particular authentication of users within the virtual environment. As a first step towards seamless VR authentication, this paper investigates the direct transfer of well-established concepts (PIN, Android unlock patterns) into VR. In a pilot study (N = 5) and a lab study (N = 25), we adapted existing mechanisms and evaluated their usability and security for VR. The results indicate that both PINs and patterns are well suited for authentication in VR. We found that the usability of both methods matched the performance known from the physical world. In addition, the private visual channel makes authentication harder to observe, indicating that authentication in VR using traditional concepts already achieves a good balance in the trade-off between usability and security. The paper contributes to a better understanding of authentication within VR environments, by providing the first investigation of established authentication methods within VR, and presents the base layer for the design of future authentication schemes, which are used in VR environments only

Zeitkippen : Begleitpublikation zum Film C 13075

If we see a film, we experience the passing time in two ways. On the one hand, it is conveyed as the time in which the film action takes place – felt as “lived” time. On the other hand, via camera travels and movements of objects vertically to the picture plane, time is perceived – in a much more indirect way – as a vehicle for representation of spatial depth. It is this link between space and time where the method of “time tilting” introduced here sets in. When a film scene is “time-tilted”, one of the spatial dimensions (here the horizontal direction of the picture plane) is interchanged with the time dimension: In a first step, the pictures of the scene are digitalized. Then, the thus gained pixels of all pictures of the scene are arranged into a three-dimensional data field. Finally, a new series of pictures is read out, along one of the two former picture axes, which is then shown as a scene of moving pictures. The resulting film will present optical phenomena which are, on the one hand, aesthetically appealing and, on the other hand, informative for film analysis. First examples demonstrate how the procedure operates on basic movements in space as well as on camera travels in space.Bei der Vorführung eines Films wirkt die ablaufende Zeit auf den Zuschauer in zweierlei Weise. Zum einen als die Zeit, in der die Filmhandlung stattfindet und die als gelebte Zeit empfunden wird. Zum anderen, sehr viel indirekter, als Vehikel zur Darstellung von Raumtiefe durch Kamerafahrten und Objektbewegungen senkrecht zur Bildebene. An dieser Verknüpfung von Raum und Zeit setzt die hier vorgestellte Methode „Zeitkippen“ an. Beim Zeitkippen einer Filmszene wird eine der Raumdimensionen (hier die Horizontale der Bildebene) mit der Zeitachse vertauscht: Im ersten Schritt digitalisiert man die Szene. Dann fügt man die Bildpunkte (Pixel) aller Szenen bilder in ein dreidimensionales Datenfeld. Schließlich liest man entlang einer der beiden ehemaligen Bildfeldachsen eine neue Bildserie aus, die man als Bewegtbild-Szene vorführt. Dabei entstehen einerseits ästhetisch ansprechende und andererseits filmanalytisch auf schlussreiche optische Phänomene. Erste Beispiele zeigen, wie sich das Verfahren auf grundlegende Bewegungen im Raum sowie Kamerafahrten im Raum auswirkt

Relative authenticity : abstraction and the digital domain

This paper intends to offer a preliminary investigation of what will be referred to as the notion of ‘abstraction’ in relation to Sigmund Freud’s ideas of ‘condensation’ and ‘displacement’, together with Ferdinand de Saussure’s theory of signification. Abstraction, then, shall be defined as one process through which a ‘signifier’ is created. The argument shall aim to trace and retrace the cognitive process of abstraction by discussing its role across different facets and layers of contemporary society, with particular attention being paid to the effects of the digital on this role. Abstractions shall be discussed regarding how they occur both in principle and in practice, and in how they might be perceived. This shall lead to a series of hypotheses concerning reflections and reactions which the omnipresence of the digital domain in every-day life might be prompting in contemporary society. The paper shall also focus on the parallel phenomena of ‘relative reality’ and ‘relative authenticity’, which can be understood as the hypothetical middle ground or gradient existing between ‘real’ and ‘fake’, and which shall be argued to be direct implications of abstraction.peer-reviewe

'Don't box me in': Blurred lines in 'Waking Life' and 'A Scanner Darkly'

This is the author's accepted manuscript. The final published article is available from the link below.This article seeks to evaluate the visual style of Waking Life and A Scanner Darkly, predominantly through an analysis of the films’ aesthetics. The use of Rotoshop as an expressive means to illustrate character and theme, where identity becomes sketched and multi-faceted rather than fixed or stable is explored here. Yet this aesthetic play with borders has a greater resonance than simply a means by which to delineate thematic preoccupations with troubled identity. While such representations are indeed key to these two films, the darkly outlined contours of character borders, which move and slide incessantly, also comment on the blurred divide between live action and animation. Central to the argument is the use of the animated line in understanding these two films; the line provides impetus for exploring several issues raised by the films and the use of Rotoshop. This article explores the following key ideas: the animated line and aesthetic analysis; Rotoshop technology; the representation of fragmentary identity; and the relationship between photo-real cinema and animation, with a particular focus on narrative and spectacle. The author addresses Rotoshop within the context of technology and spectacle; taking industry practices into account allows for an appreciation of how a technological innovation such as Rotoshop can change the shape of live-action cinema

Event-based Vision: A Survey

Event cameras are bio-inspired sensors that differ from conventional frame cameras: Instead of capturing images at a fixed rate, they asynchronously measure per-pixel brightness changes, and output a stream of events that encode the time, location and sign of the brightness changes. Event cameras offer attractive properties compared to traditional cameras: high temporal resolution (in the order of microseconds), very high dynamic range (140 dB vs. 60 dB), low power consumption, and high pixel bandwidth (on the order of kHz) resulting in reduced motion blur. Hence, event cameras have a large potential for robotics and computer vision in challenging scenarios for traditional cameras, such as low-latency, high speed, and high dynamic range. However, novel methods are required to process the unconventional output of these sensors in order to unlock their potential. This paper provides a comprehensive overview of the emerging field of event-based vision, with a focus on the applications and the algorithms developed to unlock the outstanding properties of event cameras. We present event cameras from their working principle, the actual sensors that are available and the tasks that they have been used for, from low-level vision (feature detection and tracking, optic flow, etc.) to high-level vision (reconstruction, segmentation, recognition). We also discuss the techniques developed to process events, including learning-based techniques, as well as specialized processors for these novel sensors, such as spiking neural networks. Additionally, we highlight the challenges that remain to be tackled and the opportunities that lie ahead in the search for a more efficient, bio-inspired way for machines to perceive and interact with the world

Towards binocular active vision in a robot head system

This paper presents the first results of an investigation and pilot study into an active, binocular vision system that combines binocular vergence, object recognition and attention control in a unified framework. The prototype developed is capable of identifying, targeting, verging on and recognizing objects in a highly-cluttered scene without the need for calibration or other knowledge of the camera geometry. This is achieved by implementing all image analysis in a symbolic space without creating explicit pixel-space maps. The system structure is based on the ‘searchlight metaphor’ of biological systems. We present results of a first pilot investigation that yield a maximum vergence error of 6.4 pixels, while seven of nine known objects were recognized in a high-cluttered environment. Finally a “stepping stone” visual search strategy was demonstrated, taking a total of 40 saccades to find two known objects in the workspace, neither of which appeared simultaneously within the Field of View resulting from any individual saccade