33,139 research outputs found
Video Stream Retrieval of Unseen Queries using Semantic Memory
Retrieval of live, user-broadcast video streams is an under-addressed and
increasingly relevant challenge. The on-line nature of the problem requires
temporal evaluation and the unforeseeable scope of potential queries motivates
an approach which can accommodate arbitrary search queries. To account for the
breadth of possible queries, we adopt a no-example approach to query retrieval,
which uses a query's semantic relatedness to pre-trained concept classifiers.
To adapt to shifting video content, we propose memory pooling and memory
welling methods that favor recent information over long past content. We
identify two stream retrieval tasks, instantaneous retrieval at any particular
time and continuous retrieval over a prolonged duration, and propose means for
evaluating them. Three large scale video datasets are adapted to the challenge
of stream retrieval. We report results for our search methods on the new stream
retrieval tasks, as well as demonstrate their efficacy in a traditional,
non-streaming video task.Comment: Presented at BMVC 2016, British Machine Vision Conference, 201
Visual Information Retrieval in Endoscopic Video Archives
In endoscopic procedures, surgeons work with live video streams from the
inside of their subjects. A main source for documentation of procedures are
still frames from the video, identified and taken during the surgery. However,
with growing demands and technical means, the streams are saved to storage
servers and the surgeons need to retrieve parts of the videos on demand. In
this submission we present a demo application allowing for video retrieval
based on visual features and late fusion, which allows surgeons to re-find
shots taken during the procedure.Comment: Paper accepted at the IEEE/ACM 13th International Workshop on
Content-Based Multimedia Indexing (CBMI) in Prague (Czech Republic) between
10 and 12 June 201
Online Product Quantization
Approximate nearest neighbor (ANN) search has achieved great success in many
tasks. However, existing popular methods for ANN search, such as hashing and
quantization methods, are designed for static databases only. They cannot
handle well the database with data distribution evolving dynamically, due to
the high computational effort for retraining the model based on the new
database. In this paper, we address the problem by developing an online product
quantization (online PQ) model and incrementally updating the quantization
codebook that accommodates to the incoming streaming data. Moreover, to further
alleviate the issue of large scale computation for the online PQ update, we
design two budget constraints for the model to update partial PQ codebook
instead of all. We derive a loss bound which guarantees the performance of our
online PQ model. Furthermore, we develop an online PQ model over a sliding
window with both data insertion and deletion supported, to reflect the
real-time behaviour of the data. The experiments demonstrate that our online PQ
model is both time-efficient and effective for ANN search in dynamic large
scale databases compared with baseline methods and the idea of partial PQ
codebook update further reduces the update cost.Comment: To appear in IEEE Transactions on Knowledge and Data Engineering
(DOI: 10.1109/TKDE.2018.2817526
Multimedia information technology and the annotation of video
The state of the art in multimedia information technology has not progressed to the point where a single solution is available to meet all reasonable needs of documentalists and users of video archives. In general, we do not have an optimistic view of the usability of new technology in this domain, but digitization and digital power can be expected to cause a small revolution in the area of video archiving. The volume of data leads to two views of the future: on the pessimistic side, overload of data will cause lack of annotation capacity, and on the optimistic side, there will be enough data from which to learn selected concepts that can be deployed to support automatic annotation. At the threshold of this interesting era, we make an attempt to describe the state of the art in technology. We sample the progress in text, sound, and image processing, as well as in machine learning
Second-order Temporal Pooling for Action Recognition
Deep learning models for video-based action recognition usually generate
features for short clips (consisting of a few frames); such clip-level features
are aggregated to video-level representations by computing statistics on these
features. Typically zero-th (max) or the first-order (average) statistics are
used. In this paper, we explore the benefits of using second-order statistics.
Specifically, we propose a novel end-to-end learnable feature aggregation
scheme, dubbed temporal correlation pooling that generates an action descriptor
for a video sequence by capturing the similarities between the temporal
evolution of clip-level CNN features computed across the video. Such a
descriptor, while being computationally cheap, also naturally encodes the
co-activations of multiple CNN features, thereby providing a richer
characterization of actions than their first-order counterparts. We also
propose higher-order extensions of this scheme by computing correlations after
embedding the CNN features in a reproducing kernel Hilbert space. We provide
experiments on benchmark datasets such as HMDB-51 and UCF-101, fine-grained
datasets such as MPII Cooking activities and JHMDB, as well as the recent
Kinetics-600. Our results demonstrate the advantages of higher-order pooling
schemes that when combined with hand-crafted features (as is standard practice)
achieves state-of-the-art accuracy.Comment: Accepted in the International Journal of Computer Vision (IJCV
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