11,526 research outputs found
Encouraging LSTMs to Anticipate Actions Very Early
In contrast to the widely studied problem of recognizing an action given a
complete sequence, action anticipation aims to identify the action from only
partially available videos. As such, it is therefore key to the success of
computer vision applications requiring to react as early as possible, such as
autonomous navigation. In this paper, we propose a new action anticipation
method that achieves high prediction accuracy even in the presence of a very
small percentage of a video sequence. To this end, we develop a multi-stage
LSTM architecture that leverages context-aware and action-aware features, and
introduce a novel loss function that encourages the model to predict the
correct class as early as possible. Our experiments on standard benchmark
datasets evidence the benefits of our approach; We outperform the
state-of-the-art action anticipation methods for early prediction by a relative
increase in accuracy of 22.0% on JHMDB-21, 14.0% on UT-Interaction and 49.9% on
UCF-101.Comment: 13 Pages, 7 Figures, 11 Tables. Accepted in ICCV 2017. arXiv admin
note: text overlap with arXiv:1611.0552
Action-Conditional Video Prediction using Deep Networks in Atari Games
Motivated by vision-based reinforcement learning (RL) problems, in particular
Atari games from the recent benchmark Aracade Learning Environment (ALE), we
consider spatio-temporal prediction problems where future (image-)frames are
dependent on control variables or actions as well as previous frames. While not
composed of natural scenes, frames in Atari games are high-dimensional in size,
can involve tens of objects with one or more objects being controlled by the
actions directly and many other objects being influenced indirectly, can
involve entry and departure of objects, and can involve deep partial
observability. We propose and evaluate two deep neural network architectures
that consist of encoding, action-conditional transformation, and decoding
layers based on convolutional neural networks and recurrent neural networks.
Experimental results show that the proposed architectures are able to generate
visually-realistic frames that are also useful for control over approximately
100-step action-conditional futures in some games. To the best of our
knowledge, this paper is the first to make and evaluate long-term predictions
on high-dimensional video conditioned by control inputs.Comment: Published at NIPS 2015 (Advances in Neural Information Processing
Systems 28
Multi-Label Zero-Shot Human Action Recognition via Joint Latent Ranking Embedding
Human action recognition refers to automatic recognizing human actions from a
video clip. In reality, there often exist multiple human actions in a video
stream. Such a video stream is often weakly-annotated with a set of relevant
human action labels at a global level rather than assigning each label to a
specific video episode corresponding to a single action, which leads to a
multi-label learning problem. Furthermore, there are many meaningful human
actions in reality but it would be extremely difficult to collect/annotate
video clips regarding all of various human actions, which leads to a zero-shot
learning scenario. To the best of our knowledge, there is no work that has
addressed all the above issues together in human action recognition. In this
paper, we formulate a real-world human action recognition task as a multi-label
zero-shot learning problem and propose a framework to tackle this problem in a
holistic way. Our framework holistically tackles the issue of unknown temporal
boundaries between different actions for multi-label learning and exploits the
side information regarding the semantic relationship between different human
actions for knowledge transfer. Consequently, our framework leads to a joint
latent ranking embedding for multi-label zero-shot human action recognition. A
novel neural architecture of two component models and an alternate learning
algorithm are proposed to carry out the joint latent ranking embedding
learning. Thus, multi-label zero-shot recognition is done by measuring
relatedness scores of action labels to a test video clip in the joint latent
visual and semantic embedding spaces. We evaluate our framework with different
settings, including a novel data split scheme designed especially for
evaluating multi-label zero-shot learning, on two datasets: Breakfast and
Charades. The experimental results demonstrate the effectiveness of our
framework.Comment: 27 pages, 10 figures and 7 tables. Technical report submitted to a
journal. More experimental results/references were added and typos were
correcte
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