82 research outputs found
Learning Robot Activities from First-Person Human Videos Using Convolutional Future Regression
We design a new approach that allows robot learning of new activities from
unlabeled human example videos. Given videos of humans executing the same
activity from a human's viewpoint (i.e., first-person videos), our objective is
to make the robot learn the temporal structure of the activity as its future
regression network, and learn to transfer such model for its own motor
execution. We present a new deep learning model: We extend the state-of-the-art
convolutional object detection network for the representation/estimation of
human hands in training videos, and newly introduce the concept of using a
fully convolutional network to regress (i.e., predict) the intermediate scene
representation corresponding to the future frame (e.g., 1-2 seconds later).
Combining these allows direct prediction of future locations of human hands and
objects, which enables the robot to infer the motor control plan using our
manipulation network. We experimentally confirm that our approach makes
learning of robot activities from unlabeled human interaction videos possible,
and demonstrate that our robot is able to execute the learned collaborative
activities in real-time directly based on its camera input
Forecasting Hands and Objects in Future Frames
This paper presents an approach to forecast future presence and location of
human hands and objects. Given an image frame, the goal is to predict what
objects will appear in the future frame (e.g., 5 seconds later) and where they
will be located at, even when they are not visible in the current frame. The
key idea is that (1) an intermediate representation of a convolutional object
recognition model abstracts scene information in its frame and that (2) we can
predict (i.e., regress) such representations corresponding to the future frames
based on that of the current frame. We design a new two-stream convolutional
neural network (CNN) architecture for videos by extending the state-of-the-art
convolutional object detection network, and present a new fully convolutional
regression network for predicting future scene representations. Our experiments
confirm that combining the regressed future representation with our detection
network allows reliable estimation of future hands and objects in videos. We
obtain much higher accuracy compared to the state-of-the-art future object
presence forecast method on a public dataset
Identifying First-person Camera Wearers in Third-person Videos
We consider scenarios in which we wish to perform joint scene understanding,
object tracking, activity recognition, and other tasks in environments in which
multiple people are wearing body-worn cameras while a third-person static
camera also captures the scene. To do this, we need to establish person-level
correspondences across first- and third-person videos, which is challenging
because the camera wearer is not visible from his/her own egocentric video,
preventing the use of direct feature matching. In this paper, we propose a new
semi-Siamese Convolutional Neural Network architecture to address this novel
challenge. We formulate the problem as learning a joint embedding space for
first- and third-person videos that considers both spatial- and motion-domain
cues. A new triplet loss function is designed to minimize the distance between
correct first- and third-person matches while maximizing the distance between
incorrect ones. This end-to-end approach performs significantly better than
several baselines, in part by learning the first- and third-person features
optimized for matching jointly with the distance measure itself
Characterization of macular lesions in punctate inner choroidopathy with spectral domain optical coherence tomography.
PURPOSE: Punctate inner choroidopathy (PIC) is an ocular inflammatory disease. Spectral domain optical coherence tomography (SD-OCT) allows detailed visualization of retinal and choroidal structures. We aimed to describe the retinal changes on SD-OCT associated with PIC lesions localized in the macula.
METHODS: Retrospective case series: PIC lesions not associated with choroidal neovascularization (CNV) and captured by macular SD-OCT scans were identified and characterized.
RESULTS: Twenty-seven PIC lesions from seven patients (eight eyes) were identified and classified into four categories according to disease activity and temporal changes. Among clinically inactive patients, two main patterns were noted on OCT: (1) retinal pigment epithelium (RPE) elevation with sub-RPE hyper-reflective signals and (2) localized disruption of outer retinal layers with choroid and Bruch\u27s membrane (BM) generally spared. Clinically active patients demonstrated lesions with intact BM with RPE elevation that fluctuated with disease activity and sub-RPE hyper-reflective signals. Photoreceptor-associated bands on SD-OCT (PRs) were not visible during active disease, but returned to normal visibility when lesions were clinically stable. Seven lesions in patients without clinically detected activity demonstrated alteration of RPE elevation.
CONCLUSION: SD-OCT can provide detailed structural characteristics of PIC lesions. RPE elevation is noted in many lesions while BM and choroid are spared. Photoreceptor-associated bands on SD-OCT appear compressed during clinically active stages and are visible during stabilization. OCT may provide information on activity not detected clinically
Importance of proper diagnosis for management: multifocal choroiditis mimicking ocular histoplasmosis syndrome
PURPOSE: The study aims to evaluate a series of patients with initial diagnosis of ocular histoplasmosis syndrome (OHS) with progression and response to treatments consistent with multifocal choroiditis (MFC).
METHODS: Retrospective review of nine patients referred for management of recurrent OHS lesions. Serology panel was conducted to rule out autoimmune and infectious causes.
RESULTS: Clinical examination revealed multiple small, punched-out peripheral chorioretinal scars, and peripapillary atrophy. Histoplasma antigen/antibody was negative in all patients. Fluorescein angiography and optical coherence tomography confirmed active inflammation in five patients. Immunomodulatory therapy (IMT) was initiated to control active inflammation. While on IMT, visual acuity stabilized or improved in three patients with no recurrence of CNV or lesion activities over the follow-up period.
CONCLUSIONS: MFC may initially masquerade as OHS. Clinical characteristics of recurrent MFC and absence of histoplasma titer may lead to consideration of IMT and other proper treatments for MFC
Strongly adhesive dry transfer technique for van der Waals heterostructure
That one can stack van der Waals materials with atomically sharp interfaces
has provided a new material platform of constructing heterostructures. The
technical challenge of mechanical stacking is picking up the exfoliated
atomically thin materials after mechanical exfoliation without chemical and
mechanical degradation. Chemically inert hexagonal boron nitride (hBN) has been
widely used for encapsulating and picking up vdW materials. However, due to the
relatively weak adhesion of hBN, assembling vdW heterostructures based on hBN
has been limited. We report a new dry transfer technique. We used two vdW
semiconductors (ZnPS3 and CrPS4) to pick up and encapsulate layers for vdW
heterostructures, which otherwise are known to be hard to fabricate. By
combining with optimized polycaprolactone (PCL) providing strong adhesion, we
demonstrated various vertical heterostructure devices, including quasi-2D
superconducting NbSe2 Josephson junctions with atomically clean interface. The
versatility of the PCL-based vdW stacking method provides a new route for
assembling complex 2D vdW materials without interfacial degradation.Comment: Accepted for publication in 2D Material
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