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Luca Carlone - One of the best experts on this subject based on the ideXlab platform.
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3d dynamic scene graphs actionable Spatial Perception with places objects and humans
Robotics: Science and Systems, 2020Co-Authors: Antoni Rosinol, Arjun Gupta, Marcus Abate, Jingnan Shi, Luca CarloneAbstract:We present a unified representation for actionable Spatial Perception: 3D Dynamic Scene Graphs. Scene graphs are directed graphs where nodes represent entities in the scene (e.g. objects, walls, rooms), and edges represent relations (e.g. inclusion, adjacency) among nodes. Dynamic scene graphs (DSGs) extend this notion to represent dynamic scenes with moving agents (e.g. humans, robots), and to include actionable information that supports planning and decision-making (e.g. spatio-temporal relations, topology at different levels of abstraction). Our second contribution is to provide the first fully automatic Spatial Perception eNgine(SPIN) to build a DSG from visual-inertial data. We integrate state-of-the-art techniques for object and human detection and pose estimation, and we describe how to robustly infer object, robot, and human nodes in crowded scenes. To the best of our knowledge, this is the first paper that reconciles visual-inertial SLAM and dense human mesh tracking. Moreover, we provide algorithms to obtain hierarchical representations of indoor environments (e.g. places, structures, rooms) and their relations. Our third contribution is to demonstrate the proposed Spatial Perception engine in a photo-realistic Unity-based simulator, where we assess its robustness and expressiveness. Finally, we discuss the implications of our proposal on modern robotics applications. 3D Dynamic Scene Graphs can have a profound impact on planning and decision-making, human-robot interaction, long-term autonomy, and scene prediction. A video abstract is available at this https URL
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graduated non convexity for robust Spatial Perception from non minimal solvers to global outlier rejection
International Conference on Robotics and Automation, 2020Co-Authors: Heng Yang, Vasileios Tzoumas, Pasquale Antonante, Luca CarloneAbstract:Semidefinite Programming (SDP) and Sums-of-Squ- ares (SOS) relaxations have led to certifiably optimal non-minimal solvers for several robotics and computer vision problems. However, most non-minimal solvers rely on least squares formulations, and, as a result, are brittle against outliers. While a standard approach to regain robustness against outliers is to use robust cost functions, the latter typically introduce other non-convexities, preventing the use of existing non-minimal solvers. In this letter, we enable the simultaneous use of non-minimal solvers and robust estimation by providing a general-purpose approach for robust global estimation, which can be applied to any problem where a non-minimal solver is available for the outlier-free case. To this end, we leverage the Black-Rangarajan duality between robust estimation and outlier processes (which has been traditionally applied to early vision problems), and show that graduated non-convexity ( GNC ) can be used in conjunction with non-minimal solvers to compute robust solutions, without requiring an initial guess. we demonstrate the resulting robust non-minimal solvers in applications, including point cloud and mesh registration, pose graph optimization, and image-based object pose estimation (also called shape alignment ). Our solvers are robust to 70–80% of outliers, outperform RANSAC , are more accurate than specialized local solvers, and faster than specialized global solvers. We also propose the first certifiably optimal non-minimal solver for shape alignment using SOS relaxation.
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outlier robust Spatial Perception hardness general purpose algorithms and guarantees
Intelligent Robots and Systems, 2019Co-Authors: Vasileios Tzoumas, Pasquale Antonante, Luca CarloneAbstract:Spatial Perception is the backbone of many robotics applications, and spans a broad range of research problems, including localization and mapping, point cloud alignment, and relative pose estimation from camera images. Robust Spatial Perception is jeopardized by the presence of incorrect data association, and in general, outliers. Although techniques to handle outliers do exist, they can fail in unpredictable manners (e.g., RANSAC, robust estimators), or can have exponential runtime (e.g., branch-and-bound). In this paper, we advance the state of the art in outlier rejection by making three contributions. First, we show that even a simple linear instance of outlier rejection is inapproximable: in the worst-case one cannot design a quasi-polynomial time algorithm that computes an approximate solution efficiently. Our second contribution is to provide the first per-instance sub-optimality bounds to assess the approximation quality of a given outlier rejection outcome. Our third contribution is to propose a simple general-purpose algorithm, named adaptive trimming, to remove outliers. Our algorithm leverages recently-proposed global solvers that are able to solve outlier-free problems, and iteratively removes measurements with large errors. We demonstrate the proposed algorithm on three Spatial Perception problems: 3D registration, two-view geometry, and SLAM. The results show that our algorithm outperforms several state-of-the-art methods across applications while being a general-purpose method.
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graduated non convexity for robust Spatial Perception from non minimal solvers to global outlier rejection
arXiv: Computer Vision and Pattern Recognition, 2019Co-Authors: Heng Yang, Vasileios Tzoumas, Pasquale Antonante, Luca CarloneAbstract:Semidefinite Programming (SDP) and Sums-of-Squares (SOS) relaxations have led to certifiably optimal non-minimal solvers for several robotics and computer vision problems. However, most non-minimal solvers rely on least-squares formulations, and, as a result, are brittle against outliers. While a standard approach to regain robustness against outliers is to use robust cost functions, the latter typically introduce other non-convexities, preventing the use of existing non-minimal solvers. In this paper, we enable the simultaneous use of non-minimal solvers and robust estimation by providing a general-purpose approach for robust global estimation, which can be applied to any problem where a non-minimal solver is available for the outlier-free case. To this end, we leverage the Black-Rangarajan duality between robust estimation and outlier processes (which has been traditionally applied to early vision problems), and show that graduated non-convexity (GNC) can be used in conjunction with non-minimal solvers to compute robust solutions, without requiring an initial guess. Although GNC's global optimality cannot be guaranteed, we demonstrate the empirical robustness of the resulting robust non-minimal solvers in applications, including point cloud and mesh registration, pose graph optimization, and image-based object pose estimation (also called shape alignment). Our solvers are robust to 70-80% of outliers, outperform RANSAC, are more accurate than specialized local solvers, and faster than specialized global solvers. We also propose the first certifiably optimal non-minimal solver for shape alignment using SOS relaxation.
Lorimer G Moseley - One of the best experts on this subject based on the ideXlab platform.
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Spatially defined modulation of skin temperature and hand ownership of both hands in patients with unilateral complex regional pain syndrome
Brain, 2012Co-Authors: Lorimer G Moseley, Alberto Gallace, Gian Domenico IannettiAbstract:Numerous clinical conditions, including complex regional pain syndrome, are characterized by autonomic dysfunctions (e.g. altered thermoregulation, sometimes confined to a single limb), and disrupted cortical representation of the body and the surrounding space. The presence, in patients with complex regional pain syndrome, of a disruption in Spatial Perception, bodily ownership and thermoregulation led us to hypothesize that impaired Spatial Perception might result in a Spatial-dependent modulation of thermoregulation and bodily ownership over the affected limb. In five experiments involving a total of 23 patients with complex regional pain syndrome of one arm and 10 healthy control subjects, we measured skin temperature of the hand with infrared thermal imaging, before and after experimental periods of either 9 or 10 min each, during which the hand was held on one or the other side of the body midline. Tactile processing was assessed by temporal order judgements of pairs of vibrotactile stimuli, delivered one to each hand. Pain and sense of ownership over the hand were assessed by self-report scales. Across experiments, when kept on its usual side of the body midline, the affected hand was 0.5 ± 0.3°C cooler than the healthy hand (P < 0.02 for all, a common finding in cold-type complex regional pain syndrome), and tactile stimuli delivered to the healthy hand were prioritized over those delivered to the affected hand. Simply crossing both hands over the midline resulted in (i) warming of the affected hand (the affected hand became 0.4 ± 0.3°C warmer than when it was in the uncrossed position; P = 0.01); (ii) cooling of the healthy hand (by 0.3 ± 0.3°C; P = 0.02); and (iii) reversal of the prioritization of tactile processing. When only the affected hand was crossed over the midline, it became warmer (by 0.5 ± 0.3°C; P = 0.01). When only the healthy hand was crossed over the midline, it became cooler (by 0.3 ± 0.3°C; P = 0.01). The temperature change of either hand was positively related to its distance from the body midline (pooled data: r = 0.76, P < 0.001). Crossing the affected hand over the body midline had small but significant effects on both spontaneous pain (which was reduced) and the sense of ownership over the hand (which was increased) (P < 0.04 for both). We conclude that impaired Spatial Perception modulated temperature of the limbs, tactile processing, spontaneous pain and the sense of ownership over the hands. These results show that complex regional pain syndrome involves more complex neurological dysfunction than has previously been considered.
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impact of tactile dysfunction on upper limb motor performance in children with unilateral cerebral palsy
Archives of Physical Medicine and Rehabilitation, 2012Co-Authors: Megan L Auld, Lorimer G Moseley, Roslyn N Boyd, Robert S Ware, Leanne M JohnstonAbstract:Abstract Auld ML, Boyd RN, Moseley GL, Ware RS, Johnston LM. Impact of tactile dysfunction on upper-limb motor performance in children with unilateral cerebral palsy. Objective To determine the relationship between tactile function and upper-limb function in children with unilateral cerebral palsy (CP). Design Cross-sectional study. Setting Assessments were performed in community or hospital venues or in participants' homes. Participants Recruitment information was sent to 253 possible participants with unilateral CP (aged 8–18y), and N=52 participated (median age [interquartile range], 12y [9–14y]; Gross Motor Functional Classification System level I=34; II=18; Manual Abilities Classification Scale level I=36; II=16). Interventions Not applicable. Main Outcome Measures Tactile assessment included 1 test of registration, 5 tests for Spatial Perception, and 1 test for texture Perception. Upper-limb motor function was assessed using 2 unimanual tests, the Melbourne Unilateral Upper Limb Assessment (MUUL) and Jebsen-Taylor Test of Hand Function (JTTHF), and 1 bimanual test, the Assisting Hand Assessment (AHA). Results Tactile registration and all tests of Spatial Perception were moderately related to the MUUL, JTTHF, and AHA ( P Conclusions Spatial tactile deficits account for approximately 30% of the variance in upper-limb motor function in children with unilateral CP. This emphasizes the need for routine tactile assessment and targeted treatment of tactile Spatial deficits in this population.
Chaz Firestone - One of the best experts on this subject based on the ideXlab platform.
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how paternalistic is Spatial Perception why wearing a heavy backpack doesn t and couldn t make hills look steeper
Perspectives on Psychological Science, 2013Co-Authors: Chaz FirestoneAbstract:A chief goal of Perception is to help us navigate our environment. According to a rich and ambitious theory of Spatial Perception, the visual system achieves this goal not by aiming to accurately depict the external world, but instead by actively distorting the environment’s perceived Spatial layout to bias action selection toward favorable outcomes. Scores of experimental results have supported this view—including, famously, a report that wearing a heavy backpack makes hills look steeper. This perspective portrays the visual system as unapologetically paternalistic: Backpacks make hills harder to climb, so vision steepens them to discourage ascent. The “paternalistic” theory of Spatial Perception has, understandably, attracted controversy; if true, it would radically revise our understanding of how and why we see. Here, this view is subjected to a kind and degree of scrutiny it has yet to face. After characterizing and motivating the case for paternalistic vision, I expose several unexplored defects in i...
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how paternalistic is Spatial Perception why wearing a heavy backpack doesn t and couldn t make hills look steeper
Perspectives on Psychological Science, 2013Co-Authors: Chaz FirestoneAbstract:A chief goal of Perception is to help us navigate our environment. According to a rich and ambitious theory of Spatial Perception, the visual system achieves this goal not by aiming to accurately depict the external world, but instead by actively distorting the environment's perceived Spatial layout to bias action selection toward favorable outcomes. Scores of experimental results have supported this view-including, famously, a report that wearing a heavy backpack makes hills look steeper. This perspective portrays the visual system as unapologetically paternalistic: Backpacks make hills harder to climb, so vision steepens them to discourage ascent. The "paternalistic" theory of Spatial Perception has, understandably, attracted controversy; if true, it would radically revise our understanding of how and why we see. Here, this view is subjected to a kind and degree of scrutiny it has yet to face. After characterizing and motivating the case for paternalistic vision, I expose several unexplored defects in its theoretical framework, arguing that extant accounts of how and why Spatial Perception is ability-sensitive are deeply problematic and that perceptual phenomenology belies the view's claims. The paternalistic account of Spatial Perception not only isn't true-it couldn't be true, even if its empirical findings were accepted at face value.
Hans-otto Karnath - One of the best experts on this subject based on the ideXlab platform.
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The role of the right superior temporal gyrus in visual search-insights from intraoperative electrical stimulation.
Neuropsychologia, 2006Co-Authors: Alireza Gharabaghi, Monika Fruhmann Berger, Marcos Tatagiba, Hans-otto KarnathAbstract:Intraoperative electrical stimulation in awake patients is a seminal technique during brain surgery allowing one to infer the function of brain areas by temporary inactivation. Using this technique, we found that inactivation of the middle portion of the superior temporal gyrus (STG) leads to disturbed serial exploratory visual search. The data supplement recent findings by Ellison et al. [Ellison, A., Schindler, I., Pattison, L. L., & Milner, A. D. (2004). An exploration of the role of the superior temporal gyrus in visual search and Spatial Perception using TMS. Brain, 127, 2307-2315] using repetitive transcranial magnetic stimulation over the STG in healthy subjects. Our data demonstrate that the STG is integral to human exploration behaviour and challenge the traditional view that only the right posterior parietal cortex is involved in the mediation of visual search processes.
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Spatial orientation and the representation of space with parietal lobe lesions.
Philosophical Transactions of the Royal Society B, 1997Co-Authors: Hans-otto KarnathAbstract:Damage to the human parietal cortex leads to disturbances of Spatial Perception and of motor behaviour. Within the parietal lobe, lesions of the superior and of the inferior lobule induce quite dif...
Simon Carlile - One of the best experts on this subject based on the ideXlab platform.
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the plastic ear and perceptual relearning in auditory Spatial Perception
Frontiers in Neuroscience, 2014Co-Authors: Simon CarlileAbstract:The auditory system of adult listeners has been shown to accommodate to altered spectral cues to sound location which presumably provides the basis for recalibration to changes in the shape of the ear over a life time. Here we review the role of auditory and non-auditory inputs to the Perception of sound location and consider a range of recent experiments looking at the role of non-auditory inputs in the process of accommodation to these altered spectral cues. A number of studies have used small ear moulds to modify the spectral cues that result in significant degradation in localization performance. Following chronic exposure (10-60 days) performance recovers to some extent and recent work has demonstrated that this occurs for both audio-visual and audio-only regions of space. This begs the questions as to the teacher signal for this remarkable functional plasticity in the adult nervous system. Following a brief review of influence of the motor state in auditory localisation, we consider the potential role of auditory-motor learning in the perceptual recalibration of the spectral cues. Several recent studies have considered how multi-modal and sensory-motor feedback might influence accommodation to altered spectral cues produced by ear moulds or through virtual auditory space stimulation using non-individualised spectral cues. The work with ear moulds demonstrates that a relatively short period of training involving sensory-motor feedback (5 – 10 days) significantly improved both the rate and extent of accommodation to altered spectral cues. This has significant implications not only for the mechanisms by which this complex sensory information is encoded to provide a Spatial code but also for adaptive training to altered auditory inputs. The review concludes by considering the implications for rehabilitative training with hearing aids and cochlear prosthesis.
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compression of auditory space during rapid head turns
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Johahn Leung, David Alais, Simon CarlileAbstract:Studies of Spatial Perception during visual saccades have demonstrated compressions of visual space around the saccade target. Here we psychophysically investigated Perception of auditory space during rapid head turns, focusing on the "perisaccadic" interval. Using separate perceptual and behavioral response measures we show that Spatial compression also occurs for rapid head movements, with the auditory Spatial representation compressing by up to 50%. Similar to observations in the visual system, this occurred only when Spatial locations were measured by using a perceptual response; it was absent for the behavioral measure involving a nose-pointing task. These findings parallel those observed in vision during saccades and suggest that a common neural mechanism may subserve these distortions of space in each modality.
