3,820 research outputs found
ModDrop: adaptive multi-modal gesture recognition
We present a method for gesture detection and localisation based on
multi-scale and multi-modal deep learning. Each visual modality captures
spatial information at a particular spatial scale (such as motion of the upper
body or a hand), and the whole system operates at three temporal scales. Key to
our technique is a training strategy which exploits: i) careful initialization
of individual modalities; and ii) gradual fusion involving random dropping of
separate channels (dubbed ModDrop) for learning cross-modality correlations
while preserving uniqueness of each modality-specific representation. We
present experiments on the ChaLearn 2014 Looking at People Challenge gesture
recognition track, in which we placed first out of 17 teams. Fusing multiple
modalities at several spatial and temporal scales leads to a significant
increase in recognition rates, allowing the model to compensate for errors of
the individual classifiers as well as noise in the separate channels.
Futhermore, the proposed ModDrop training technique ensures robustness of the
classifier to missing signals in one or several channels to produce meaningful
predictions from any number of available modalities. In addition, we
demonstrate the applicability of the proposed fusion scheme to modalities of
arbitrary nature by experiments on the same dataset augmented with audio.Comment: 14 pages, 7 figure
Learning without Prejudice: Avoiding Bias in Webly-Supervised Action Recognition
Webly-supervised learning has recently emerged as an alternative paradigm to
traditional supervised learning based on large-scale datasets with manual
annotations. The key idea is that models such as CNNs can be learned from the
noisy visual data available on the web. In this work we aim to exploit web data
for video understanding tasks such as action recognition and detection. One of
the main problems in webly-supervised learning is cleaning the noisy labeled
data from the web. The state-of-the-art paradigm relies on training a first
classifier on noisy data that is then used to clean the remaining dataset. Our
key insight is that this procedure biases the second classifier towards samples
that the first one understands. Here we train two independent CNNs, a RGB
network on web images and video frames and a second network using temporal
information from optical flow. We show that training the networks independently
is vastly superior to selecting the frames for the flow classifier by using our
RGB network. Moreover, we show benefits in enriching the training set with
different data sources from heterogeneous public web databases. We demonstrate
that our framework outperforms all other webly-supervised methods on two public
benchmarks, UCF-101 and Thumos'14.Comment: Submitted to CVIU SI: Computer Vision and the We
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