5,676 research outputs found
The Perceptual Genesis of Near Versus Far in Pictorial Stimuli
The experiments reported herein probe the visual cortical mechanisms that control near-far percepts in response to two-dimensional stimuli. Figural contrast is found to be a principal factor for the emergence of percepts of near versus far in pictorial stimuli, especially when stimulus duration is brief. Pictorial factors such as interposition (Experiment 1) and partial occlusion (Experiments 2 and 3) may cooperate or compete with contrast factors, in the manner predicted by the FACADE model. In particular, if the geometrical configuration of an image favors activation of cortical bipole grouping cells, as at the top of aT-junction, then this advantage can cooperate with the contrast of the configuration to facilitate a near-far percept at a lower contrast than at an X-junction. The more balanced bipole competition in the X-junction case takes longer to resolve than in the T-junction case (Experiment 3).Human Frontier Science Program Organization (SF9/98); Defense Research Projects Agency and the Office of Naval Research (N00014-92-J-I309, N00014-95-1-0494, N00014-95-1-0657
The Perceptual Genesis of Near Versus Far in Pictorial Stimuli
The experiments reported herein probe the visual cortical mechanisms that control near-far percepts in response to two-dimensional stimuli. Figural contrast is found to be a principal factor for the emergence of percepts of near versus far in pictorial stimuli, especially when stimulus duration is brief. Pictorial factors such as interposition (Experiment 1) and partial occlusion (Experiments 2 and 3) may cooperate or compete with contrast factors, in the manner predicted by the FACADE model. In particular, if the geometrical configuration of an image favors activation of cortical bipole grouping cells, as at the top of aT-junction, then this advantage can cooperate with the contrast of the configuration to facilitate a near-far percept at a lower contrast than at an X-junction. The more balanced bipole competition in the X-junction case takes longer to resolve than in the T-junction case (Experiment 3).Human Frontier Science Program Organization (SF9/98); Defense Research Projects Agency and the Office of Naval Research (N00014-92-J-I309, N00014-95-1-0494, N00014-95-1-0657
Reno-mesentero-aorto-iliac thromboendarterectomy in patient with malignant hypertension
1. 1. A case is documented in which there was complete occlusion of the left renal artery and partial occlusion of the right renal and superior mesenteric arteries, complicating extensive aortoiliac thrombosis. 2. 2. The patient presented with malignant hypertension, intermittent claudication, and abdominal complaints suggestive of "intestinal angina." 3. 3. Treatment consisted of thromboendarterectomy of all involved vessels, following which the patient became normotensive and had cessation of the abdominal symptoms. 4. 4. The case is thought to be the first successful bilateral simultaneous renal endarterectomy, and the third successful case of superior mesenteric endarterectomy. © 1959
DeepVoting: A Robust and Explainable Deep Network for Semantic Part Detection under Partial Occlusion
In this paper, we study the task of detecting semantic parts of an object,
e.g., a wheel of a car, under partial occlusion. We propose that all models
should be trained without seeing occlusions while being able to transfer the
learned knowledge to deal with occlusions. This setting alleviates the
difficulty in collecting an exponentially large dataset to cover occlusion
patterns and is more essential. In this scenario, the proposal-based deep
networks, like RCNN-series, often produce unsatisfactory results, because both
the proposal extraction and classification stages may be confused by the
irrelevant occluders. To address this, [25] proposed a voting mechanism that
combines multiple local visual cues to detect semantic parts. The semantic
parts can still be detected even though some visual cues are missing due to
occlusions. However, this method is manually-designed, thus is hard to be
optimized in an end-to-end manner.
In this paper, we present DeepVoting, which incorporates the robustness shown
by [25] into a deep network, so that the whole pipeline can be jointly
optimized. Specifically, it adds two layers after the intermediate features of
a deep network, e.g., the pool-4 layer of VGGNet. The first layer extracts the
evidence of local visual cues, and the second layer performs a voting mechanism
by utilizing the spatial relationship between visual cues and semantic parts.
We also propose an improved version DeepVoting+ by learning visual cues from
context outside objects. In experiments, DeepVoting achieves significantly
better performance than several baseline methods, including Faster-RCNN, for
semantic part detection under occlusion. In addition, DeepVoting enjoys
explainability as the detection results can be diagnosed via looking up the
voting cues
On Shape-Mediated Enrolment in Ear Biometrics
Ears are a new biometric with major advantage in that they appear to maintain their shape with increased age. Any automatic biometric system needs enrolment to extract the target area from the background. In ear biometrics the inputs are often human head profile images. Furthermore ear biometrics is concerned with the effects of partial occlusion mostly caused by hair and earrings. We propose an ear enrolment algorithm based on finding the elliptical shape of the ear using a Hough Transform (HT) accruing tolerance to noise and occlusion. Robustness is improved further by enforcing some prior knowledge. We assess our enrolment on two face profile datasets; as well as synthetic occlusion
Cell nuclei detection using globally optimal active contours with shape prior
Cell nuclei detection in fluorescent microscopic images is an important and time consuming task for a wide range of biological applications. Blur, clutter, bleed through and partial occlusion of nuclei make this a challenging task for automated detection of individual nuclei using image analysis. This paper proposes a novel and robust detection method based on the active contour framework. The method exploits prior knowledge of the nucleus shape in order to better detect individual nuclei. The method is formulated as the optimization of a convex energy function. The proposed method shows accurate detection results even for clusters of nuclei where state of the art methods fail
Facial Expression Analysis under Partial Occlusion: A Survey
Automatic machine-based Facial Expression Analysis (FEA) has made substantial
progress in the past few decades driven by its importance for applications in
psychology, security, health, entertainment and human computer interaction. The
vast majority of completed FEA studies are based on non-occluded faces
collected in a controlled laboratory environment. Automatic expression
recognition tolerant to partial occlusion remains less understood, particularly
in real-world scenarios. In recent years, efforts investigating techniques to
handle partial occlusion for FEA have seen an increase. The context is right
for a comprehensive perspective of these developments and the state of the art
from this perspective. This survey provides such a comprehensive review of
recent advances in dataset creation, algorithm development, and investigations
of the effects of occlusion critical for robust performance in FEA systems. It
outlines existing challenges in overcoming partial occlusion and discusses
possible opportunities in advancing the technology. To the best of our
knowledge, it is the first FEA survey dedicated to occlusion and aimed at
promoting better informed and benchmarked future work.Comment: Authors pre-print of the article accepted for publication in ACM
Computing Surveys (accepted on 02-Nov-2017
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