159,204 research outputs found
A 3D descriptor to detect task-oriented grasping points in clothing
© 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Manipulating textile objects with a robot is a challenging task, especially because the garment perception is difficult due to the endless configurations it can adopt, coupled with a large variety of colors and designs. Most current approaches follow a multiple re-grasp strategy, in which clothes are sequentially grasped from different points until one of them yields a recognizable configuration. In this work we propose a method that combines 3D and appearance information to directly select a suitable grasping point for the task at hand, which in our case consists of hanging a shirt or a polo shirt from a hook. Our method follows a coarse-to-fine approach in which, first, the collar of the garment is detected and, next, a grasping point on the lapel is chosen using a novel 3D descriptor.
In contrast to current 3D descriptors, ours can run in real time, even when it needs to be densely computed over the input image. Our central idea is to take advantage of the structured nature of range images that most depth sensors provide and, by exploiting integral imaging, achieve speed-ups of two orders of magnitude with respect to competing approaches, while maintaining performance. This makes it especially adequate for robotic applications as we thoroughly demonstrate in the experimental section.Peer ReviewedPostprint (author's final draft
Estudo experimental do comportamento ocular em trabalhadores administrativos como um indicador de conforto visual em situação de risco de encadeamento
The daylight impact on the visual environment is fundamental on visual display terminal work (VDT). Visual performance and visual comfort should be considered for equal. The study (n=16) was performed at the experimental lighting laboratory. Office work with VDT was evaluated using STROOP task in two orientations: (with/without solar presence in the visual field). Our hypothesis states the existence of a relationship between ocular behavior and visual comfort of workers. An eye-tracker was employed in order to record the ocular gestural parameters: blinks, direction of gaze, eye aperture (Degree of eye?s openness) and pupil size, which were correlated with the vertical illuminance at the eye. Visual comfort was assessed with Glare Sensation Vote. Results indicate a strong negative linear correlation between eye illuminance and the degree of eye?s openness in the direct sunlight scenario (p=-0.636; s=0.008) and in diffuse light scenario (p=-0.661; s=0.005), that could be the main predictor of visual discomfort. This experiment allowed us to explore eye behavior patterns that could be visual comfort indices under glare risk situations.O impacto a luz do dia no ambiente visual é fundamental para o trabalho no Ecrã de
Visualização de Dados (EDV). Desempenho visual e conforto visual devem ser considerados em igual. O estudo (n = 16) foi realizado no laboratório experimental de iluminação. O trabalho de escritório com EDV foi avaliado utilizando a tarefa de Stroop em duas orientações: (com / sem presença solar no campo visual). A nossa hipótese afirma a existência de uma relação entre o comportamento ocular e
conforto visual dos trabalhadores. Um “eye-tracker” foi desenvolvido para gravar os parâmetros gestuais oculares: pestanejar, direção do olhar, abertura dos olhos (Grau de abertura do olho) e tamanho da pupila, que foram correlacionados com a iluminância vertical no olho. Conforto visual foi avaliado com a escala de sensação de encadeamento. Os resultados indicam uma correlação linear negativa forte entre a luminosidade dos olhos e do grau de abertura de olho no cenário de luz solar
direta (p = -0,636; s = 0,008) e no cenário de luz difusa (p = -0,661; s = 0,005), que poderia ser o principal preditor de desconforto visual. Esta experiência permitiu-nos explorar padrões de comportamento do olho que poderiam ser os índices de conforto visual em situação de risco de encadeamento.Fil: Yamin Garretón, Julieta Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ciencias Humanas, Sociales y Ambientales; ArgentinaFil: Rodriguez, Roberto Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ciencias Humanas, Sociales y Ambientales; ArgentinaFil: Pattini, Andrea Elvira. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ciencias Humanas, Sociales y Ambientales; Argentin
Provably scale-covariant networks from oriented quasi quadrature measures in cascade
This article presents a continuous model for hierarchical networks based on a
combination of mathematically derived models of receptive fields and
biologically inspired computations. Based on a functional model of complex
cells in terms of an oriented quasi quadrature combination of first- and
second-order directional Gaussian derivatives, we couple such primitive
computations in cascade over combinatorial expansions over image orientations.
Scale-space properties of the computational primitives are analysed and it is
shown that the resulting representation allows for provable scale and rotation
covariance. A prototype application to texture analysis is developed and it is
demonstrated that a simplified mean-reduced representation of the resulting
QuasiQuadNet leads to promising experimental results on three texture datasets.Comment: 12 pages, 3 figures, 1 tabl
Counterbalancing for serial order carryover effects in experimental condition orders
Reactions of neural, psychological, and social systems are rarely, if ever, independent of previous inputs and states. The potential for serial order carryover effects from one condition to the next in a sequence of experimental trials makes counterbalancing of condition order an essential part of experimental design. Here, a method is proposed for generating counterbalanced sequences for repeated-measures designs including those with multiple observations of each condition on one participant and self-adjacencies of conditions. Condition ordering is reframed as a graph theory problem. Experimental conditions are represented as vertices in a graph and directed edges between them represent temporal relationships between conditions. A counterbalanced trial order results from traversing an Euler circuit through such a graph in which each edge is traversed exactly once. This method can be generalized to counterbalance for higher order serial order carryover effects as well as to create intentional serial order biases. Modern graph theory provides tools for finding other types of paths through such graph representations, providing a tool for generating experimental condition sequences with useful properties
Orientation of particle attachment and local isotropy in diffusion limited aggregation (DLA)
We simulate 50 off-lattice DLA clusters, one million particles each. The
probability distribution of the angle of attachment of arriving particles with
respect to the local radial direction is obtained numerically. For increasing
cluster size, , the distribution crosses over extremely accurately to a
cosine, whose amplitude decreases towards zero as a power-law in . From this
viewpoint, asymptotically large DLA clusters are locally . This
contradicts previous conclusions drawn from density-density correlation
measurements [P. Meakin, and T. Viscek, Phys. Rev. A {\bf 32}, 685 (1985)]. We
present an intuitive phenomenological model random process for our numerical
findings.Comment: 10 pages, RevTex 3.0, 11-9
Integrating Multiple 3D Views through Frame-of-reference Interaction
Frame-of-reference interaction consists of a unified set of 3D interaction techniques for exploratory navigation of large virtual spaces in nonimmersive environments. It is based on a conceptual framework that considers navigation from a cognitive perspective, as a way of facilitating changes in user attention from one reference frame to another, rather than from the mechanical perspective of moving a camera between different points of interest. All of our techniques link multiple frames of reference in some meaningful way. Some techniques link multiple windows within a zooming environment while others allow seamless changes of user focus between static objects, moving objects, and groups of moving objects. We present our techniques as they are implemented in GeoZui3D, a geographic visualization system for ocean data
Orientation to the sun by animals and its interaction with crypsis
1. Orientation with respect to the sun has been observed in a wide range of species and hasgenerally been interpreted in terms of thermoregulation and/or ultraviolet (UV) protection. For countershaded animals, orientation with respect to the sun may also result from the pres-sure to exploit the gradient of coloration optimally to enhance crypsis.2. Here, we use computational modelling to predict the optimal countershading pattern for anoriented body. We assess how camouflage performance declines as orientation varies using acomputational model that incorporates realistic lighting environments.3. Once an optimal countershading pattern for crypsis has been chosen, we determineseparately how UV protection/irradiation and solar thermal inflow fluctuate with orientation.4. We show that body orientations that could optimally use countershading to enhance crypsisare very similar to those that allow optimal solar heat inflow and UV protection.5. Our findings suggest that crypsis has been overlooked as a selective pressure on orientationand that new experiments should be designed to tease apart the respective roles of these different selective pressures. We propose potential experiments that could achieve this
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