11,813 research outputs found
Deep Learning on Lie Groups for Skeleton-based Action Recognition
In recent years, skeleton-based action recognition has become a popular 3D
classification problem. State-of-the-art methods typically first represent each
motion sequence as a high-dimensional trajectory on a Lie group with an
additional dynamic time warping, and then shallowly learn favorable Lie group
features. In this paper we incorporate the Lie group structure into a deep
network architecture to learn more appropriate Lie group features for 3D action
recognition. Within the network structure, we design rotation mapping layers to
transform the input Lie group features into desirable ones, which are aligned
better in the temporal domain. To reduce the high feature dimensionality, the
architecture is equipped with rotation pooling layers for the elements on the
Lie group. Furthermore, we propose a logarithm mapping layer to map the
resulting manifold data into a tangent space that facilitates the application
of regular output layers for the final classification. Evaluations of the
proposed network for standard 3D human action recognition datasets clearly
demonstrate its superiority over existing shallow Lie group feature learning
methods as well as most conventional deep learning methods.Comment: Accepted to CVPR 201
Indoor Activity Detection and Recognition for Sport Games Analysis
Activity recognition in sport is an attractive field for computer vision
research. Game, player and team analysis are of great interest and research
topics within this field emerge with the goal of automated analysis. The very
specific underlying rules of sports can be used as prior knowledge for the
recognition task and present a constrained environment for evaluation. This
paper describes recognition of single player activities in sport with special
emphasis on volleyball. Starting from a per-frame player-centered activity
recognition, we incorporate geometry and contextual information via an activity
context descriptor that collects information about all player's activities over
a certain timespan relative to the investigated player. The benefit of this
context information on single player activity recognition is evaluated on our
new real-life dataset presenting a total amount of almost 36k annotated frames
containing 7 activity classes within 6 videos of professional volleyball games.
Our incorporation of the contextual information improves the average
player-centered classification performance of 77.56% by up to 18.35% on
specific classes, proving that spatio-temporal context is an important clue for
activity recognition.Comment: Part of the OAGM 2014 proceedings (arXiv:1404.3538
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