86,164 research outputs found
Adaptive Temporal Encoding Network for Video Instance-level Human Parsing
Beyond the existing single-person and multiple-person human parsing tasks in
static images, this paper makes the first attempt to investigate a more
realistic video instance-level human parsing that simultaneously segments out
each person instance and parses each instance into more fine-grained parts
(e.g., head, leg, dress). We introduce a novel Adaptive Temporal Encoding
Network (ATEN) that alternatively performs temporal encoding among key frames
and flow-guided feature propagation from other consecutive frames between two
key frames. Specifically, ATEN first incorporates a Parsing-RCNN to produce the
instance-level parsing result for each key frame, which integrates both the
global human parsing and instance-level human segmentation into a unified
model. To balance between accuracy and efficiency, the flow-guided feature
propagation is used to directly parse consecutive frames according to their
identified temporal consistency with key frames. On the other hand, ATEN
leverages the convolution gated recurrent units (convGRU) to exploit temporal
changes over a series of key frames, which are further used to facilitate the
frame-level instance-level parsing. By alternatively performing direct feature
propagation between consistent frames and temporal encoding network among key
frames, our ATEN achieves a good balance between frame-level accuracy and time
efficiency, which is a common crucial problem in video object segmentation
research. To demonstrate the superiority of our ATEN, extensive experiments are
conducted on the most popular video segmentation benchmark (DAVIS) and a newly
collected Video Instance-level Parsing (VIP) dataset, which is the first video
instance-level human parsing dataset comprised of 404 sequences and over 20k
frames with instance-level and pixel-wise annotations.Comment: To appear in ACM MM 2018. Code link:
https://github.com/HCPLab-SYSU/ATEN. Dataset link: http://sysu-hcp.net/li
Towards High Performance Video Object Detection
There has been significant progresses for image object detection in recent
years. Nevertheless, video object detection has received little attention,
although it is more challenging and more important in practical scenarios.
Built upon the recent works, this work proposes a unified approach based on
the principle of multi-frame end-to-end learning of features and cross-frame
motion. Our approach extends prior works with three new techniques and steadily
pushes forward the performance envelope (speed-accuracy tradeoff), towards high
performance video object detection
Depth Estimation via Affinity Learned with Convolutional Spatial Propagation Network
Depth estimation from a single image is a fundamental problem in computer
vision. In this paper, we propose a simple yet effective convolutional spatial
propagation network (CSPN) to learn the affinity matrix for depth prediction.
Specifically, we adopt an efficient linear propagation model, where the
propagation is performed with a manner of recurrent convolutional operation,
and the affinity among neighboring pixels is learned through a deep
convolutional neural network (CNN). We apply the designed CSPN to two depth
estimation tasks given a single image: (1) To refine the depth output from
state-of-the-art (SOTA) existing methods; and (2) to convert sparse depth
samples to a dense depth map by embedding the depth samples within the
propagation procedure. The second task is inspired by the availability of
LIDARs that provides sparse but accurate depth measurements. We experimented
the proposed CSPN over two popular benchmarks for depth estimation, i.e. NYU v2
and KITTI, where we show that our proposed approach improves in not only
quality (e.g., 30% more reduction in depth error), but also speed (e.g., 2 to 5
times faster) than prior SOTA methods.Comment: 14 pages, 8 figures, ECCV 201
Heliospheric tracking of enhanced density structures of the 6 October 2010 CME
A Coronal Mass Ejection (CME) is an inhomogeneous structure consisting of
different features which evolve differently with the propagation of the CME.
Simultaneous heliospheric tracking of different observed features of a CME can
improve our understanding about relative forces acting on them. It also helps
to estimate accurately their arrival times at the Earth and identify them in
in- situ data. This also enables to find association between remotely observed
features and in-situ observations near the Earth. In this paper, we attempt to
continuously track two density enhanced features, one at the front and another
at the rear edge of the 6 October 2010 CME. This is achieved by using
time-elongation maps constructed from STEREO/SECCHI observations. We derive the
kinematics of the tracked features using various reconstruction methods. The
estimated kinematics are used as inputs in the Drag Based Model (DBM) to
estimate the arrival time of the tracked features of the CME at L1. On
comparing the estimated kinematics as well as the arrival times of the remotely
observed features with in-situ observations by ACE and Wind, we find that the
tracked bright feature in the J-map at the rear edge of 6 October 2010 CME
corresponds most probably to the enhanced density structure after the magnetic
cloud detected by ACE and Wind. In-situ plasma and compositional parameters
provide evidence that the rear edge density structure may correspond to a
filament associated with the CME while the density enhancement at the front
corresponds to the leading edge of the CME. Based on this single event study,
we discuss the relevance and significance of heliospheric imager (HI)
observations in identification of the three-part structure of the CME.Comment: 27 pages, 9 figures, accepted for Journal of Space Weather and Space
Climate (SWSC
Omnipresent long-period intensity oscillations in open coronal structures
Quasi-periodic propagating disturbances in coronal structures have been
interpreted as slow magneto-acoustic waves and/or periodic upflows. Here we aim
to understand their nature from the observed properties using a three-hour
imaging sequence from AIA/SDO in two different temperature channels. We also
compare the characteristics with a simple wave model. We searched for
propagating disturbances in open-loop structures at three different locations;
a fan loop-structure off-limb, an on-disk plume-like structure and the
plume/interplume regions in the north pole of the sun. In each of the subfield
regions chosen to cover these structures, the time series at each pixel
location was subjected to wavelet analysis to find the different periodicities.
We then constructed powermaps in three different period ranges. We also
constructed space-time maps for the on-disk plume structure to estimate the
propagation speeds in different channels. We find propagating disturbances in
all three structures. Powermaps indicate that the power in the long-period
range is significant up to comparatively longer distances along the loop than
that in the shorter periods. This nature is observed in all three structures. A
detailed analysis on the on-disk plume structure gives consistently higher
propagation speeds in the 193 \AA channel and also reveals spatial damping
along the loop. The amplitude and the damping length values are lower in hotter
channels, indicating their acoustic dependence. These properties can be
explained very well with a propagating slow-wave model. We suggest that these
disturbances are more likely to be caused by propagating slow magneto-acoustic
waves than by high-speed quasi-periodic upflows. We find that intensity
oscillations in longer periods are omnipresent at larger heights even in active
regions.Comment: accepted for publication in A &
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