Publication details

Searching for Variable-Speed Motions in Long Sequences of Motion Capture Data

Authors

SEDMIDUBSKÝ Jan ELIÁŠ Petr ZEZULA Pavel

Type Article in Periodical
Magazine / Source Information Systems
MU Faculty or unit

Faculty of Informatics

Citation
Doi http://dx.doi.org/10.1016/j.is.2018.04.002
Keywords Content-based retrieval;Motion capture data;Subsequence matching;Speed-invariant retrieval;Similarity measure;Hierarchical segmentation;Indexing
Description Motion capture data digitally represent human movements by sequences of body configurations in time. Subsequence searching in long sequences of such spatio-temporal data is difficult as query-relevant motions can vary in execution speeds and styles and can occur anywhere in a very long data sequence. To deal with these problems, we employ a fast and effective similarity measure that is elastic. The property of elasticity enables matching of two overlapping but slightly misaligned subsequences with a high confidence. Based on the elasticity, the long data sequence is partitioned into overlapping segments that are organized in multiple levels. The number of levels and sizes of overlaps are optimized to generate a modest number of segments while being able to trace an arbitrary query. In a retrieval phase, a query is always represented as a single segment and fast matched against segments within a relevant level without any costly post-processing. Moreover, visiting adjacent levels makes possible subsequence searching of time-warped (i.e., faster or slower executed) queries. To efficiently search on a large scale, segment features can be binarized and segmentation levels independently indexed. We experimentally demonstrate effectiveness and efficiency of the proposed approach for subsequence searching on a real-life dataset.
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