Cross-modal Representation Learning for Zero-shot Action Recognition
This work addresses the problem of recognizing unseen actions in videos for computer vision applications, representing an incremental improvement over existing methods.
The authors tackled zero-shot action recognition by developing a cross-modal Transformer framework that jointly learns video and text representations, achieving state-of-the-art top-1 accuracy on UCF101, HMDB51, and ActivityNet benchmarks without pre-training on additional datasets.
We present a cross-modal Transformer-based framework, which jointly encodes video data and text labels for zero-shot action recognition (ZSAR). Our model employs a conceptually new pipeline by which visual representations are learned in conjunction with visual-semantic associations in an end-to-end manner. The model design provides a natural mechanism for visual and semantic representations to be learned in a shared knowledge space, whereby it encourages the learned visual embedding to be discriminative and more semantically consistent. In zero-shot inference, we devise a simple semantic transfer scheme that embeds semantic relatedness information between seen and unseen classes to composite unseen visual prototypes. Accordingly, the discriminative features in the visual structure could be preserved and exploited to alleviate the typical zero-shot issues of information loss, semantic gap, and the hubness problem. Under a rigorous zero-shot setting of not pre-training on additional datasets, the experiment results show our model considerably improves upon the state of the arts in ZSAR, reaching encouraging top-1 accuracy on UCF101, HMDB51, and ActivityNet benchmark datasets. Code will be made available.