View-Independent Action Recognition from Temporal Self-Similarities

— This paper addresses recognition of human actions under view changes. We explore self-similarities of action sequences over time and observe the striking stability of such measures across views. Building upon this key observation, we develop an action descriptor that captures the structure of temporal similarities and dissimilarities within an action sequence. Despite this temporal self-similarity descriptor not being strictly view-invariant, we provide intuition and experimental validation demonstrating its high stability under view changes. Self-similarity descriptors are also shown stable under performance variations within a class of actions, when individual speed fluctuations are ignored. If required, such fluctuations between two different instances of the same action class can be explicitly recovered with dynamic time warping, as will be demonstrated, to achieve cross-view action synchronization. More central to present work, temporal ordering of local selfsimilarity descr...

• Type: Journal
• Year: 2011
• Where: PAMI
• Authors: Imran N. Junejo, Emilie Dexter, Ivan Laptev, Patrick Pérez
• Keywords: Action Sequence, Operations Research, PAMI 2011, Self-similarity Descriptors, View Changes