Learning Multimodal Representations for Sampleefficient Recognition of Human Actions Humans interact in rich and diverse ways with the environment. However, the representation of such behavior by artificial agents is often limited. In this work we present motion concepts, a novel multimodal representation of human actions in a household environment. A motion concept encompasses a probabilistic description of the kinematics of the action along with its contextual background, namely the location and the objects held during the performance. We introduce a novel algorithm which learns and recognizes motion concepts from action demonstrations, named Online Motion Concept Learning (OMCL). The algorithm is evaluated on a virtualreality household environment with the presence of a human avatar. OMCL outperforms standard motion recognition algorithms on an oneshot recognition task, attesting to its potential for sampleefficient recognition of human actions.

Augmenting SpatioTemporal Human Motion Data for Effective 3D Action Recognition Action recognition is a fundamental operation in 3D human motion analysis. Existing deep learning classifiers achieve a high recognition accuracy if large amounts of training data are provided. However, such data are difficult to obtain in a variety of application scenarios, mainly due to the high costs of motion capture technologies and an absence of suitable actors. In this paper, we propose augmentation techniques to artificially enlarge existing collections of 3D human skeleton sequences. The proposed techniques are especially useful for datasets distinguishing in a high number of classes, each of them characterized by only a limited number of action samples. We experimentally demonstrate that the augmented data help to significantly increase the recognition accuracy even using a standard deep learning architecture.