Shape Perception of Clear Water in Photo-Realistic Images

Light plays a vital role in the perception of transparency, depth and shape of liquids. The perception of the surfaces of liquids is made possible with an understanding of refraction of light and knowledge of the underlying texture geometry. Given this, what specific characteristics of the natural optical environment are essential to the perception of transparent liquids, specifically with respect to efficiency and realism? In this thesis, a light path triangulation method for the recovery of transparent surface shape and a system to estimate the perceived shape of any arbitrary-shaped object with a refractive surface are proposed. A psycho-physical experiment was conducted to investigate this using the perceived shape of water from stereo images using a real time stereoscopic 3-D depth gauge. The results suggest that people are able to consistently perceive shape of liquids from photo-realistic images and that regularity in underlying texture facilitates human judgement of surface shape

The kinesfield : a study of movement-based interactive and choreographic art

Merged with duplicate record 10026.1/680 on 14.03.2017 by CS (TIS)Through the exploration of practice and theory, this thesis aims to elucidate the characteristics of movement-based interactive art and the kinesfield, a term developed during the course of the research to describe the publics' body-medium. Movement-based interactive art is based on choreographed movements of the body, media and specialized technologies which facilitate new forms of participatory movement experience. This emergent art form has initiated new methods of experiencing and presenting dance in the public domain. lt is argued that this leads to new artistic developments which may constitute a paradigm shift of the concept of the body-medium in the field of dance. To understand whether the shift is indeed paradigmatic, and to contribute to the development of dance and technology, this study introduces and applies the concept of the kinesfield to extend the theory of the body-medium as kinesphere, first proposed by Laban, and to challenge its characteristics in the context of movement-based interactive art. The concept of the kinesfield is employed to describe the relational dynamic of movement interactions which traverse the body and material forms in unbounded space. By this account, the body-medium is not defined geometrically, as in Laban's theory, but as a temporal and spatial field. The kinesfield accounts for a complexity of movement characteristics which pertain to the dynamic and relational experiences which occur between the biological body and its natural and atmospheric surroundings, natural forces, and its socio-cultural milieu. The argument unfolds as a triangulation of three movement-based interactive artworks (Shifting Ground, trajets, and Raumspielpuzzle) presented during the course of the thesis, my physical and experiential knowledge in the field of dance and an interdisciplinary literature investigation in the fields of dance, physiology/psychology/cognitive science, philosophy and sociology, plastic arts and cinema. This written document is accompanied by a CD-ROM which serves as an electronic appendix including images, videos and diagrams of the works referenced in the written thesis.This thesis is a discussion of the experiential and conceptual characteristics which underpin the choreographic research of three movement-based interactive artworks I, Shifting Ground ( 1999), trajets (2000) and Raumspielpuzzle (2003). 2 In addition to elucidating an emergent mode of choreographic practice,3 this thesis proposes a new term which offers a description of the body-medium4 materialised in choreographic movement-based interactive art, namely the kinesfield

Investigating the 'Uncatchable Smile' in Leonardo da Vinci’s La Bella Principessa: A Comparison with the Mona Lisa and Pollaiuolo’s Portrait of a Girl

This paper discusses how the 'Uncatchable Smile' illusion in Leonardo da Vinci's La Bella Principessa portrait was discovered. Kemp and Cotte1 described the expression of the Princess as ambiguous and "subtle to an inexpressible degree". A combination of three methods was used (inter-observation, structured interviews, and psychophysical experiments) to identify what may underlie this 'ambiguity'. The inter-observation and the structured interview methods were firstly applied to generate experimental hypotheses that were successively tested by a series of psychophysical experiments. The combination of these research methods minimizes the impact of the researcher’s beliefs and biases in the development of the research design. It emerged that the ambiguity in La Bella Principessa is triggered by a change in the perceived level of contentment in her facial expression and that this perceptual change is attributable to a visual illusion relating to her mouth. Moreover, it was found that a similar effect can be observed in the Mona Lisa. As the smile in La Bella Principessa disappears as soon as the viewer tries to ‘catch it’, we named this visual illusion the 'Uncatchable Smile'. The elusive quality of the Mona Lisa’s smile2 is probably why the portrait is so famous, and so the existence of a similar ambiguity in a portrait painted by Leonardo prior to the Mona Lisa is even more interesting

A luminance-contrast-aware disparity model and applications

Binocular disparity is one of the most important depth cues used by the human visual system. Recently developed stereo-perception models allow us to successfully manipulate disparity in order to improve viewing comfort, depth discrimination as well as stereo content compression and display. Nonetheless, all existing models neglect the substantial influence of luminance on stereo perception. Our work is the first to account for the interplay of luminance contrast (magnitude/frequency) and disparity and our model predicts the human response to complex stereo-luminance images. Besides improving existing disparity-model applications (e.g., difference metrics or compression), our approach offers new possibilities, such as joint luminance contrast and disparity manipulation or the optimization of auto-stereoscopic content. We validate our results in a user study, which also reveals the advantage of considering luminance contrast and its significant impact on disparity manipulation techniques.National Science Foundation (U.S.) (CGV-1111415

Aesthetic complexity: practice and perception in art & design

My research investigates the aesthetics of visual complexity in the practice and perception of visual art and design. The aim is to understand visual complexity in terms of the relationship between the objective properties of images and subjective properties of perception. I take a computational and empirical approach to this subject, incorporating methods from information theory, computer graphics, complexity theory and experimental psychology. For testing, I create cellular automata programs to generate stimulus images, and borrow other types of visual material from students and professional artists, designers and craftspeople. Visual complexity is measured in two ways: Firstly, an objective measure of complexity is based on the compression of digital image files, which provides an information-based scale of order to randomness. Secondly, psychophysical techniques are employed to measure the subjective complexity of the images and other aesthetic judgements. Research in complex systems theory and experimental aesthetics suggests that we can expect an inverted ‘U’ correlation between the two measures of complexity

Probabilistic Models of Motor Production

N. Bernstein defined the ability of the central neural system (CNS) to control many degrees of freedom of a physical body with all its redundancy and flexibility as the main problem in motor control. He pointed at that man-made mechanisms usually have one, sometimes two degrees of freedom (DOF); when the number of DOF increases further, it becomes prohibitively hard to control them. The brain, however, seems to perform such control effortlessly. He suggested the way the brain might deal with it: when a motor skill is being acquired, the brain artificially limits the degrees of freedoms, leaving only one or two. As the skill level increases, the brain gradually "frees" the previously fixed DOF, applying control when needed and in directions which have to be corrected, eventually arriving to the control scheme where all the DOF are "free". This approach of reducing the dimensionality of motor control remains relevant even today. One the possibles solutions of the Bernstetin's problem is the hypothesis of motor primitives (MPs) - small building blocks that constitute complex movements and facilitite motor learnirng and task completion. Just like in the visual system, having a homogenious hierarchical architecture built of similar computational elements may be beneficial. Studying such a complicated object as brain, it is important to define at which level of details one works and which questions one aims to answer. David Marr suggested three levels of analysis: 1. computational, analysing which problem the system solves; 2. algorithmic, questioning which representation the system uses and which computations it performs; 3. implementational, finding how such computations are performed by neurons in the brain. In this thesis we stay at the first two levels, seeking for the basic representation of motor output. In this work we present a new model of motor primitives that comprises multiple interacting latent dynamical systems, and give it a full Bayesian treatment. Modelling within the Bayesian framework, in my opinion, must become the new standard in hypothesis testing in neuroscience. Only the Bayesian framework gives us guarantees when dealing with the inevitable plethora of hidden variables and uncertainty. The special type of coupling of dynamical systems we proposed, based on the Product of Experts, has many natural interpretations in the Bayesian framework. If the dynamical systems run in parallel, it yields Bayesian cue integration. If they are organized hierarchically due to serial coupling, we get hierarchical priors over the dynamics. If one of the dynamical systems represents sensory state, we arrive to the sensory-motor primitives. The compact representation that follows from the variational treatment allows learning of a motor primitives library. Learned separately, combined motion can be represented as a matrix of coupling values. We performed a set of experiments to compare different models of motor primitives. In a series of 2-alternative forced choice (2AFC) experiments participants were discriminating natural and synthesised movements, thus running a graphics Turing test. When available, Bayesian model score predicted the naturalness of the perceived movements. For simple movements, like walking, Bayesian model comparison and psychophysics tests indicate that one dynamical system is sufficient to describe the data. For more complex movements, like walking and waving, motion can be better represented as a set of coupled dynamical systems. We also experimentally confirmed that Bayesian treatment of model learning on motion data is superior to the simple point estimate of latent parameters. Experiments with non-periodic movements show that they do not benefit from more complex latent dynamics, despite having high kinematic complexity. By having a fully Bayesian models, we could quantitatively disentangle the influence of motion dynamics and pose on the perception of naturalness. We confirmed that rich and correct dynamics is more important than the kinematic representation. There are numerous further directions of research. In the models we devised, for multiple parts, even though the latent dynamics was factorized on a set of interacting systems, the kinematic parts were completely independent. Thus, interaction between the kinematic parts could be mediated only by the latent dynamics interactions. A more flexible model would allow a dense interaction on the kinematic level too. Another important problem relates to the representation of time in Markov chains. Discrete time Markov chains form an approximation to continuous dynamics. As time step is assumed to be fixed, we face with the problem of time step selection. Time is also not a explicit parameter in Markov chains. This also prohibits explicit optimization of time as parameter and reasoning (inference) about it. For example, in optimal control boundary conditions are usually set at exact time points, which is not an ecological scenario, where time is usually a parameter of optimization. Making time an explicit parameter in dynamics may alleviate this

Operator/equipment Performance Measures: Results Of Literature Search

Literature review focuses on topics concerning perception, acceptable transmission delay, fidelity, and visual systems, including resolution, field of view, and target-background contrast

What Influences the Relative Proportion of ‘Rigid Rotation’ Versus ‘Non-Rigid Deformation’ in a Bistable Stroboscopic Motion Display

When observers are presented with a bistable stroboscopic display of an object that appears to transform over time in three-dimensional (3D) space, the dominance of one percept over another is influenced both by stimulus parameters and by cognitive factors. Two experiments were designed to reveal which of several manipulated variables influence most strongly which of two responses is more often observed, one being termed ‘Rigid Rotation’ and the other termed ‘Non-rigid Deformation.’ These two responses were clearly distinguished when drawings of a 3D rectangular box were presented stroboscopically in a two-frame animation with precise control over the Interstimulus Interval (ISI). In the first experiment, the relative dominance of the ‘Rigid Rotation’ response was reduced by changing the colour of one surface of the rectangular box in a manner that was inconsistent with the rotation of the box. Similarly, the relative dominance of the ‘Non-rigid Deformation’ response was reduced by changing the colour of one surface of the rectangular box in a manner that was inconsistent with deformation of the box. In the second experiment, the changes in the relative dominance of the competing motion percepts were observed after prolonged viewing of four different adapting stimuli. The adaptation aftereffects were shown to depend more upon the Interstimulus Interval (ISI) of the stroboscopic display of the adapting stimulus than upon what motion was reportedly ‘seen’ during the viewing of the adapting stimulus. Ultimately, the adaption aftereffect revealed that the relative dominance of the two movement percepts was affected most strongly by the manipulation of a single temporal variable – the ISI. Nonetheless, the results of the first experiment confirmed the influence of surface colour variations on ‘Rigid Rotation’ versus ‘Non-rigid Deformation’ response