The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Elizabeth L Ferrell - One of the best experts on this subject based on the ideXlab platform.
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aging and the perception of slant from optical texture Motion Parallax and binocular disparity
Attention Perception & Psychophysics, 2009Co-Authors: Farley J Norman, Charles E Crabtree, Ashley N Bartholomew, Elizabeth L FerrellAbstract:The ability of younger and older observers to perceive surface slant was investigated in four experiments. The surfaces possessed slants of 20°, 35°, 50°, and 65°, relative to the frontoparallel plane. The observers judged the slants using either a palm board (Experiments 1, 3, and 4) or magnitude estimation (Experiment 2). In Experiments 1–3, physically slanted surfaces were used (the surfaces possessed marble, granite, pebble, and circle textures), whereas computer-generated 3-D surfaces (defined by Motion Parallax and binocular disparity) were utilized in Experiment 4. The results showed that the younger and older observers' performance was essentially identical with regard to accuracy. The younger and older age groups, however, differed in terms of precision in Experiments 1 and 2: The judgments of the older observers were more variable across repeated trials. When taken as a whole, the results demonstrate that older observers (at least through the age of 83 years) can effectively extract information about slant in depth from optical patterns containing texture, Motion Parallax, or binocular disparity.
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aging and the perception of slant from optical texture Motion Parallax and binocular disparity
Attention Perception & Psychophysics, 2009Co-Authors: Farley J Norman, Charles E Crabtree, Ashley N Bartholomew, Elizabeth L FerrellAbstract:The ability of younger and older observers to perceive surface slant was investigated in four experiments. The surfaces possessed slants of 20 degrees, 35 degrees, 50 degrees, and 65 degrees, relative to the frontoparallel plane. The observers judged the slants using either a palm board (Experiments 1, 3, and 4) or magnitude estimation (Experiment 2). In Experiments 1-3, physically slanted surfaces were used (the surfaces possessed marble, granite, pebble, and circle textures), whereas computer-generated 3-D surfaces (defined by Motion Parallax and binocular disparity) were utilized in Experiment 4. The results showed that the younger and older observers' performance was essentially identical with regard to accuracy. The younger and older age groups, however, differed in terms of precision in Experiments 1 and 2: The judgments of the older observers were more variable across repeated trials. When taken as a whole, the results demonstrate that older observers (at least through the age of 83 years) can effectively extract information about slant in depth from optical patterns containing texture, Motion Parallax, or binocular disparity.
Farley J Norman - One of the best experts on this subject based on the ideXlab platform.
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aging and the perception of slant from optical texture Motion Parallax and binocular disparity
Attention Perception & Psychophysics, 2009Co-Authors: Farley J Norman, Charles E Crabtree, Ashley N Bartholomew, Elizabeth L FerrellAbstract:The ability of younger and older observers to perceive surface slant was investigated in four experiments. The surfaces possessed slants of 20 degrees, 35 degrees, 50 degrees, and 65 degrees, relative to the frontoparallel plane. The observers judged the slants using either a palm board (Experiments 1, 3, and 4) or magnitude estimation (Experiment 2). In Experiments 1-3, physically slanted surfaces were used (the surfaces possessed marble, granite, pebble, and circle textures), whereas computer-generated 3-D surfaces (defined by Motion Parallax and binocular disparity) were utilized in Experiment 4. The results showed that the younger and older observers' performance was essentially identical with regard to accuracy. The younger and older age groups, however, differed in terms of precision in Experiments 1 and 2: The judgments of the older observers were more variable across repeated trials. When taken as a whole, the results demonstrate that older observers (at least through the age of 83 years) can effectively extract information about slant in depth from optical patterns containing texture, Motion Parallax, or binocular disparity.
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aging and the perception of slant from optical texture Motion Parallax and binocular disparity
Attention Perception & Psychophysics, 2009Co-Authors: Farley J Norman, Charles E Crabtree, Ashley N Bartholomew, Elizabeth L FerrellAbstract:The ability of younger and older observers to perceive surface slant was investigated in four experiments. The surfaces possessed slants of 20°, 35°, 50°, and 65°, relative to the frontoparallel plane. The observers judged the slants using either a palm board (Experiments 1, 3, and 4) or magnitude estimation (Experiment 2). In Experiments 1–3, physically slanted surfaces were used (the surfaces possessed marble, granite, pebble, and circle textures), whereas computer-generated 3-D surfaces (defined by Motion Parallax and binocular disparity) were utilized in Experiment 4. The results showed that the younger and older observers' performance was essentially identical with regard to accuracy. The younger and older age groups, however, differed in terms of precision in Experiments 1 and 2: The judgments of the older observers were more variable across repeated trials. When taken as a whole, the results demonstrate that older observers (at least through the age of 83 years) can effectively extract information about slant in depth from optical patterns containing texture, Motion Parallax, or binocular disparity.
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aging and the perception of depth and 3 d shape from Motion Parallax
Psychology and Aging, 2004Co-Authors: Farley J Norman, Anna Marie Clayton, Cassandra F Shular, Sarah R ThompsonAbstract:The ability of younger and older observers to perceive 3-D shape and depth from Motion Parallax was investigated. In Experiment 1, the observers discriminated among differently curved 3-dimensional (3-D) surfaces in the presence of noise. In Experiment 2, the surfaces' shape was held constant and the amount of front-to-back depth was varied; the observers estimated the amount of depth they perceived. The effects of age were strongly task dependent. The younger observers' performance in Experiment 1 was almost 60% higher than that of the older observers. In contrast, no age effect was obtained in Experiment 2. Older observers can effectively perceive variations in depth from patterns of Motion Parallax, but their ability to discriminate 3-D shape is significantly compromised.
Shinji Mizuno - One of the best experts on this subject based on the ideXlab platform.
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interaction of a stereoscopic 3dcg image with Motion Parallax displayed in mid air
International Conference on Computer Graphics and Interactive Techniques, 2018Co-Authors: Mayumi Takasaki, Kyoko Ohashi, Shinji MizunoAbstract:We propose a novel system that enables a user to see stereoscopic 3DCG images in mid-air and interact with them directly as shown in Figure 1. This system displays 3DCG objects with Motion Parallax. Thus the user can observe them in mid-air while feeling a stereoscopic effect by the Motion Parallax. It is also possible to interact with the mid-air 3DCG objects by fingers. The user can move, deform and draw 3DCG objects as if they were there.
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developing a stereoscopic cg system with Motion Parallax and interactive digital contents on the system for science museums
Multimedia Tools and Applications, 2017Co-Authors: Shinji Mizuno, Mami Tsukada, Yuto UeharaAbstract:As we watch 3D objects and move around them, the appearance of the objects would change. This is called Motion Parallax and it is one of important depth cues. We develop an interactive stereoscopic CG system using Motion Parallax. This system follows the position of a user's view point, and generates 3DCG images for the view point every moment. As a result, the system can reproduce Motion Parallax and can synthesize stereoscopy without special equipments. Based on this system, we develop two interactive stereoscopic contents which would be used in science museums. One is a constellation viewer, in which we can observe constellations and planets from any positions, and can grasp positional relationships and 3D shapes of them. It is also possible to control the content with gestures. The other is a virtual 3D photocopy system. When we put physical 3D objects on a desk and remove them, we can observe virtual objects from any points as a stereoscopic 3DCG image based on Motion Parallax. We can feel the removed objects being left as they were. When the system scans moving objects, a stereoscopic 3DCG animation is synthesized and the user can observe it from any positions. It is also possible to interact with the 3DCG objects such as touching and deforming the 3DCG objects.
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a stereoscopic cg system with Motion Parallax and its digital contents for science museums
Signal-Image Technology and Internet-Based Systems, 2013Co-Authors: Shinji Mizuno, Mami Tsukada, Yuto UeharaAbstract:As we watch 3D objects and move, the appearance of the objects would change. This is called Motion Parallax and it is one of important depth cues. We develop an interactive stereoscopic CG system using Motion Parallax. This system follows the position of a user's view point, and generates 3DCG images for the view point every moment. As a result, the system can reproduce Motion Parallax and realize stereoscopy without special equipments. Based on this system, we develop two interactive stereoscopic contents which would be used in science museums. One is a constellation viewer, in which we can observe constellations and planets from any positions, and can grasp positional relationships and 3D shapes of them. The other is a virtual 3D photocopy system. When we put physical 3D objects on a desk and remove them, we can observe them from any points as a stereoscopic 3DCG image based on Motion Parallax. We can feel the removed objects being left as they were.
Gregory C Deangelis - One of the best experts on this subject based on the ideXlab platform.
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speed tuning in head coordinates as an alternative explanation of depth selectivity from Motion Parallax in area mt
bioRxiv, 2021Co-Authors: Gregory C DeangelisAbstract:Abstract There are two distinct sources of retinal image Motion: Motion of objects in the world and movement of the observer. In cases where an object moves in a scene and the eyes also move, a coordinate transformation that involves smooth eye movements and retinal Motion will be needed in order to estimate object Motion in world coordinates. More recently, interactions between retinal and eye velocity signals have also been suggested to generate depth selectivity from Motion Parallax (MP) in the macaque middle temporal (MT) area. We explored whether the nature of the interaction between eye and retinal velocities in MT neurons favors one of these two possibilities or a mixture of both. We analyzed responses of MT neurons to retinal and eye velocities in a viewing context in which the observer translates laterally while maintaining visual fixation on a world-fixed target. In this scenario, the depth of an object can be inferred from the ratio between retinal velocity and eye velocity, according to the Motion-pursuit law. Previous studies have shown that MT responses to retinal Motion are gain-modulated by the direction of eye movement, suggesting a potential mechanism for depth tuning from MP. However, our analysis of the joint tuning profile for retinal and eye velocities reveals that some MT neurons show a partial coordinate transformation toward head coordinates. We formalized a series of computational models to predict neural spike trains as well as selectivity for depth, and we used factorial model comparisons to quantify the relative importance of each model component. Our findings for many MT neurons reveal that the data are equally well explained by gain modulation or a partial coordinate transformation toward head coordinates, although some responses can only be well fit by the coordinate transform model. Our results highlight the potential role of MT neurons in representing multiple higher-level sensory variables, including depth from MP and object Motion in the world.
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gain modulation as a mechanism for coding depth from Motion Parallax in macaque area mt
The Journal of Neuroscience, 2017Co-Authors: Hyung Goo Kim, Dora E Angelaki, Gregory C DeangelisAbstract:Observer translation produces differential image Motion between objects that are located at different distances from the observer's point of fixation [Motion Parallax (MP)]. However, MP can be ambiguous with respect to depth sign (near vs far), and this ambiguity can be resolved by combining retinal image Motion with signals regarding eye movement relative to the scene. We have previously demonstrated that both extra-retinal and visual signals related to smooth eye movements can modulate the responses of neurons in area MT of macaque monkeys, and that these modulations generate neural selectivity for depth sign. However, the neural mechanisms that govern this selectivity have remained unclear. In this study, we analyze responses of MT neurons as a function of both retinal velocity and direction of eye movement, and we show that smooth eye movements modulate MT responses in a systematic, temporally precise, and directionally specific manner to generate depth-sign selectivity. We demonstrate that depth-sign selectivity is primarily generated by multiplicative modulations of the response gain of MT neurons. Through simulations, we further demonstrate that depth can be estimated reasonably well by a linear decoding of a population of MT neurons with response gains that depend on eye velocity. Together, our findings provide the first mechanistic description of how visual cortical neurons signal depth from MP.SIGNIFICANCE STATEMENT Motion Parallax is a monocular cue to depth that commonly arises during observer translation. To compute from Motion Parallax whether an object appears nearer or farther than the point of fixation requires combining retinal image Motion with signals related to eye rotation, but the neurobiological mechanisms have remained unclear. This study provides the first mechanistic account of how this interaction takes place in the responses of cortical neurons. Specifically, we show that smooth eye movements modulate the gain of responses of neurons in area MT in a directionally specific manner to generate selectivity for depth sign from Motion Parallax. We also show, through simulations, that depth could be estimated from a population of such gain-modulated neurons.
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the neural basis of depth perception from Motion Parallax
Philosophical Transactions of the Royal Society B, 2016Co-Authors: Hyung Goo Kim, Dora E Angelaki, Gregory C DeangelisAbstract:In addition to depth cues afforded by binocular vision, the brain processes relative Motion signals to perceive depth. When an observer translates relative to their visual environment, the relative Motion of objects at different distances (Motion Parallax) provides a powerful cue to three-dimensional scene structure. Although perception of depth based on Motion Parallax has been studied extensively in humans, relatively little is known regarding the neural basis of this visual capability. We review recent advances in elucidating the neural mechanisms for representing depth-sign (near versus far) from Motion Parallax. We examine a potential neural substrate in the middle temporal visual area for depth perception based on Motion Parallax, and we explore the nature of the signals that provide critical inputs for disambiguating depth-sign.This article is part of the themed issue 'Vision in our three-dimensional world'.
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a functional link between mt neurons and depth perception based on Motion Parallax
The Journal of Neuroscience, 2015Co-Authors: Hyung Goo Kim, Dora E Angelaki, Gregory C DeangelisAbstract:As an observer translates, objects lying at different distances from the observer have differential image Motion on the retina (Motion Parallax). It is well established psychophysically that humans perceive depth rather precisely from Motion Parallax and that extraretinal signals may be used to correctly perceive the sign of depth (near vs far) when binocular and pictorial depth cues are absent or weak. However, the neural basis for this capacity remains poorly understood. We have shown previously that neurons in the macaque middle temporal (MT) area combine retinal image Motion with smooth eye movement command signals to signal depth sign from Motion Parallax. However, those studies were performed in animals that were required simply to track a visual target, thus precluding direct comparisons between neural activity and behavior. Here, we examine the activity of MT neurons in rhesus monkeys that were trained to discriminate depth sign based on Motion Parallax, in the absence of binocular disparity and pictorial depth cues. We find that the most sensitive MT neurons approach behavioral sensitivity, whereas the average neuron is twofold to threefold less sensitive than the animal. We also find that MT responses are predictive of perceptual decisions (independent of the visual stimulus), consistent with a role for MT in providing sensory signals for this behavior. Our findings suggest that, in addition to its established roles in processing stereoscopic depth, area MT is well suited to contribute to perception of depth based on Motion Parallax.
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joint representation of depth from Motion Parallax and binocular disparity cues in macaque area mt
The Journal of Neuroscience, 2013Co-Authors: Jacob W Nadler, Dora E Angelaki, Hyung Goo Kim, Daniel Barbash, Swati Shimpi, Gregory C DeangelisAbstract:Perception of depth is based on a variety of cues, with binocular disparity and Motion Parallax generally providing more precise depth information than pictorial cues. Much is known about how neurons in visual cortex represent depth from binocular disparity or Motion Parallax, but little is known about the joint neural representation of these depth cues. We recently described neurons in the middle temporal (MT) area that signal depth sign (near vs far) from Motion Parallax; here, we examine whether and how these neurons also signal depth from binocular disparity. We find that most MT neurons in rhesus monkeys (Macaca Mulatta) are selective for depth sign based on both disparity and Motion Parallax cues. However, the depth-sign preferences (near or far) are not always aligned: 56% of MT neurons have matched depth-sign preferences (“congruent” cells) whereas the remaining 44% of neurons prefer near depth from Motion Parallax and far depth from disparity, or vice versa (“opposite” cells). For congruent cells, depth-sign selectivity increases when disparity cues are added to Motion Parallax, but this enhancement does not occur for opposite cells. This suggests that congruent cells might contribute to perceptual integration of depth cues. We also found that neurons are clustered in MT according to their depth tuning based on Motion Parallax, similar to the known clustering of MT neurons for binocular disparity. Together, these findings suggest that area MT is involved in constructing a representation of 3D scene structure that takes advantage of multiple depth cues available to mobile observers.
Adolfo M Bronstein - One of the best experts on this subject based on the ideXlab platform.
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influence of Motion Parallax in the control of spontaneous body sway
Experimental Brain Research, 2000Co-Authors: Michel Guerraz, V Sakellari, Peter Burchill, Adolfo M BronsteinAbstract:Visual control of postural sway during quiet standing was investigated in normal subjects to see if Motion Parallax cues were able to improve postural stability. In experiment 1, six normal subjects fixated a fluorescent foreground target, either alone or in the presence of full room illumination. The results showed that subjects reduced body sway when the background was visible. This effect, however, could be mediated not only by Parallax cues but also by an increase in the total area of visual field involved. In experiment 2, other parameters such as image angular size and target distance were controlled for. Twelve subjects fixated a two light-emitting diode (LED) target placed at 45 cm from their eyes in a dark room. A second similar two-LED target was placed either at 170 cm (maximum Parallax) or at 85 cm (medium Parallax) from the fixated target, or in the same plane of the fixated target (0 cm, no Parallax). It was found that the amplitude of sway was reduced significantly, by approximately 20%, when the two targets were presented in depth (Parallax present) as compared to when they were in the same plane (no Parallax). The effect was only present in the lateral direction and for low frequency components of sway (up to 0.5 Hz). We confirmed in experiment 3 on eight subjects with a design similar to that used in experiment 2 that the effect of Motion Parallax on body sway was of monocular origin since observed with monocular and binocular vision. Geometrical considerations based on these results support the existence of two modes of visual detection of body sway, afferent (retinal slippage) and efferent (extraretinal or eye-movement based).
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automatic control of postural sway by visual Motion Parallax
Experimental Brain Research, 1997Co-Authors: Adolfo M Bronstein, D BuckwellAbstract:The purpose of this study was to establish whether visual Motion Parallax participates in the control of postural sway. Body sway was measured in ten normal subjects by photoelectric recordings of head movements and by force-plate posturography. Subjects viewed a visual display ("background"), which briefly moved (2 s) along the y (horizontal) axis, under three different conditions: (1) direct fixation of the background, (2) fixation of a stationary window frame in the foreground, and (3) fixation of the background in the presence of the window in the foreground ("through the window"). In response to background fixation, subjects swayed in the same direction as stimulus Motion, but during foreground (window) fixation they swayed in the opposite direction. The earlier forces observed on the force platform occurred at circa 250 ms in both conditions. The results show that Motion Parallax generates postural responses. The direction of these Parallax-evoked postural responses-opposite to other visually evoked postural responses reported so far-is appropriate for stabilizating posture in natural circumstances. The findings show that Motion Parallax is an important source of self-Motion information and that this information participates in the process of automatic postural control. In the "fixating through the window" condition, which does not mimic visual conditions induced by body sway, no consistent postural responses were elicited. This implies that postural reactions elicited by visual Motion are not rigid responses to optokinetic stimulation but responses to visual stimuli signalling self-Motion.