  Gait-based person re-identification (Re-ID) is valuable for safety-critical
applications, and using only 3D skeleton data to extract discriminative gait
features for person Re-ID is an emerging open topic. Existing methods either
adopt hand-crafted features or learn gait features by traditional supervised
learning paradigms. Unlike previous methods, we for the first time propose a
generic gait encoding approach that can utilize unlabeled skeleton data to
learn gait representations in a self-supervised manner. Specifically, we first
propose to introduce self-supervision by learning to reconstruct input skeleton
sequences in reverse order, which facilitates learning richer high-level
semantics and better gait representations. Second, inspired by the fact that
motion's continuity endows temporally adjacent skeletons with higher
correlations ("locality"), we propose a locality-aware attention mechanism that
encourages learning larger attention weights for temporally adjacent skeletons
when reconstructing current skeleton, so as to learn locality when encoding
gait. Finally, we propose Attention-based Gait Encodings (AGEs), which are
built using context vectors learned by locality-aware attention, as final gait
representations. AGEs are directly utilized to realize effective person Re-ID.
Our approach typically improves existing skeleton-based methods by 10-20%
Rank-1 accuracy, and it achieves comparable or even superior performance to
multi-modal methods with extra RGB or depth information. Our codes are
available at https://github.com/Kali-Hac/SGE-LA.
