9,207 research outputs found
Multimodal Classification of Urban Micro-Events
In this paper we seek methods to effectively detect urban micro-events. Urban
micro-events are events which occur in cities, have limited geographical
coverage and typically affect only a small group of citizens. Because of their
scale these are difficult to identify in most data sources. However, by using
citizen sensing to gather data, detecting them becomes feasible. The data
gathered by citizen sensing is often multimodal and, as a consequence, the
information required to detect urban micro-events is distributed over multiple
modalities. This makes it essential to have a classifier capable of combining
them. In this paper we explore several methods of creating such a classifier,
including early, late, hybrid fusion and representation learning using
multimodal graphs. We evaluate performance on a real world dataset obtained
from a live citizen reporting system. We show that a multimodal approach yields
higher performance than unimodal alternatives. Furthermore, we demonstrate that
our hybrid combination of early and late fusion with multimodal embeddings
performs best in classification of urban micro-events
Strategies for Searching Video Content with Text Queries or Video Examples
The large number of user-generated videos uploaded on to the Internet
everyday has led to many commercial video search engines, which mainly rely on
text metadata for search. However, metadata is often lacking for user-generated
videos, thus these videos are unsearchable by current search engines.
Therefore, content-based video retrieval (CBVR) tackles this metadata-scarcity
problem by directly analyzing the visual and audio streams of each video. CBVR
encompasses multiple research topics, including low-level feature design,
feature fusion, semantic detector training and video search/reranking. We
present novel strategies in these topics to enhance CBVR in both accuracy and
speed under different query inputs, including pure textual queries and query by
video examples. Our proposed strategies have been incorporated into our
submission for the TRECVID 2014 Multimedia Event Detection evaluation, where
our system outperformed other submissions in both text queries and video
example queries, thus demonstrating the effectiveness of our proposed
approaches
A Dilated Inception Network for Visual Saliency Prediction
Recently, with the advent of deep convolutional neural networks (DCNN), the
improvements in visual saliency prediction research are impressive. One
possible direction to approach the next improvement is to fully characterize
the multi-scale saliency-influential factors with a computationally-friendly
module in DCNN architectures. In this work, we proposed an end-to-end dilated
inception network (DINet) for visual saliency prediction. It captures
multi-scale contextual features effectively with very limited extra parameters.
Instead of utilizing parallel standard convolutions with different kernel sizes
as the existing inception module, our proposed dilated inception module (DIM)
uses parallel dilated convolutions with different dilation rates which can
significantly reduce the computation load while enriching the diversity of
receptive fields in feature maps. Moreover, the performance of our saliency
model is further improved by using a set of linear normalization-based
probability distribution distance metrics as loss functions. As such, we can
formulate saliency prediction as a probability distribution prediction task for
global saliency inference instead of a typical pixel-wise regression problem.
Experimental results on several challenging saliency benchmark datasets
demonstrate that our DINet with proposed loss functions can achieve
state-of-the-art performance with shorter inference time.Comment: Accepted by IEEE Transactions on Multimedia. The source codes are
available at https://github.com/ysyscool/DINe
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