Looking into the Unknown: Exploring Action Discovery for Segmentation of Known and Unknown Actions
Looking into the Unknown: Exploring Action Discovery for Segmentation of Known and Unknown Actions
We introduce Action Discovery, a novel setup within Temporal Action Segmentation that addresses the challenge of defining and annotating ambiguous actions and incomplete annotations in partially labeled datasets. In this setup, only a subset of actions - referred to as known actions - is annotated in the training data, while other unknown actions remain unlabeled. This scenario is particularly relevant in domains like neuroscience, where well-defined behaviors (e.g., walking, eating) coexist with subtle or infrequent actions that are often overlooked, as well as in applications where datasets are inherently partially annotated due to ambiguous or missing labels. To address this problem, we propose a two-step approach that leverages the known annotations to guide both the temporal and semantic granularity of unknown action segments. First, we introduce the Granularity-Guided Segmentation Module (GGSM), which identifies temporal intervals for both known and unknown actions by mimicking the granularity of annotated actions. Second, we propose the Unknown Action Segment Assignment (UASA), which identifies semantically meaningful classes within the unknown actions, based on learned embedding similarities. We systematically explore the proposed setting of Action Discovery on three challenging datasets - Breakfast, 50Salads, and Desktop Assembly - demonstrating that our method considerably improves upon existing baselines.
Federico Spurio、Emad Bahrami、Olga Zatsarynna、Yazan Abu Farha、Gianpiero Francesca、Juergen Gall
计算技术、计算机技术
Federico Spurio,Emad Bahrami,Olga Zatsarynna,Yazan Abu Farha,Gianpiero Francesca,Juergen Gall.Looking into the Unknown: Exploring Action Discovery for Segmentation of Known and Unknown Actions[EB/OL].(2025-08-07)[2025-08-18].https://arxiv.org/abs/2508.05529.点此复制
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