34,767 research outputs found
Unified Transformer Tracker for Object Tracking
As an important area in computer vision, object tracking has formed two
separate communities that respectively study Single Object Tracking (SOT) and
Multiple Object Tracking (MOT). However, current methods in one tracking
scenario are not easily adapted to the other due to the divergent training
datasets and tracking objects of both tasks. Although UniTrack
\cite{wang2021different} demonstrates that a shared appearance model with
multiple heads can be used to tackle individual tracking tasks, it fails to
exploit the large-scale tracking datasets for training and performs poorly on
single object tracking. In this work, we present the Unified Transformer
Tracker (UTT) to address tracking problems in different scenarios with one
paradigm. A track transformer is developed in our UTT to track the target in
both SOT and MOT. The correlation between the target and tracking frame
features is exploited to localize the target. We demonstrate that both SOT and
MOT tasks can be solved within this framework. The model can be simultaneously
end-to-end trained by alternatively optimizing the SOT and MOT objectives on
the datasets of individual tasks. Extensive experiments are conducted on
several benchmarks with a unified model trained on SOT and MOT datasets. Code
will be available at https://github.com/Flowerfan/Trackron.Comment: CVPR 202
Deformable Object Tracking with Gated Fusion
The tracking-by-detection framework receives growing attentions through the
integration with the Convolutional Neural Networks (CNNs). Existing
tracking-by-detection based methods, however, fail to track objects with severe
appearance variations. This is because the traditional convolutional operation
is performed on fixed grids, and thus may not be able to find the correct
response while the object is changing pose or under varying environmental
conditions. In this paper, we propose a deformable convolution layer to enrich
the target appearance representations in the tracking-by-detection framework.
We aim to capture the target appearance variations via deformable convolution,
which adaptively enhances its original features. In addition, we also propose a
gated fusion scheme to control how the variations captured by the deformable
convolution affect the original appearance. The enriched feature representation
through deformable convolution facilitates the discrimination of the CNN
classifier on the target object and background. Extensive experiments on the
standard benchmarks show that the proposed tracker performs favorably against
state-of-the-art methods
A Tale Of Two Spicules: The Impact of Spicules on the Magnetic Chromosphere
We use high-resolution observations of the Sun in Ca II H 3968 A from the
Solar Optical Telescope on Hinode to show that there are at least two types of
spicules that dominate the structure of the magnetic solar chromosphere. Both
types are tied to the relentless magnetoconvective driving in the photosphere,
but have very different dynamic properties. ``Type-I'' spicules are driven by
shock waves that form when global oscillations and convective flows leak into
the upper atmosphere along magnetic field lines on 3-7 minute timescales.
``Type-II'' spicules are much more dynamic: they form rapidly (in ~10s), are
very thin (<200km wide), have lifetimes of 10-150s (at any one height) and seem
to be rapidly heated to (at least) transition region temperatures, sending
material through the chromosphere at speeds of order 50-150 km/s. The
properties of Type II spicules suggest a formation process that is a
consequence of magnetic reconnection, typically in the vicinity of magnetic
flux concentrations in plage and network. Both types of spicules are observed
to carry Alfven waves with significant amplitudes of order 20 km/s.Comment: 8 pages, 5 figures, accepted for Hinode special issue of PAS
(S)norlaudanosoline synthase. the first enzyme in the benzylisoquinoline biosynthetic pathway
1. introduction Isoquinoline alkaloids form the largest group of alkaloids in the plant kingdom. Numerous publications deal with aspects of the biosynthesis of these compounds in vivo [ 11, while isoquinoline biosynthesis at the cell-free level had hardly been touched [Z]. The initial reaction in isoquinoline biosynthesis has long [3] been assumed to be a condensation of two aromatic units, both derived from tyrosine, namely dopamine and 3,4-d~ydroxyphenylacet~dehyde [4]. This scheme was later modified [5] where it was reported that condensation of dopamine with 3,4-dihydroxyphenylpyruvate would lead to an amino acid, norlaudanosoline-l-carboxylic acid, which in turn, by decarboxylation, would yield norlaudanosoline
- …