Representational invariances for video action recognition. Humans recognize actions in videos effortlessly, even in the presence of large photometric, geometric, temporal, and scene variations. Injecting these task-specific video invariances through data augmentations could improve data efficiency. For each video, we show two example videos of the same action, i.e., "Tennis swing", "Basketball", "Front Crawl", and "Fencing".
Abstract
Data augmentation is a ubiquitous technique for improving image classification when labeled data is scarce.
Constraining the model predictions to be invariant to diverse data augmentations effectively injects the desired representational invariances to the model (e.g., invariance to photometric variations) and helps improve accuracy.
Compared to image data, the appearance variations in videos are far more complex due to the additional temporal dimension.
Yet, data augmentation methods for videos remain under-explored.
This paper investigates various data augmentation strategies that capture different video invariances, including photometric, geometric, temporal, and actor/scene augmentations.
When integrated with existing semi-supervised learning frameworks, we show that our data augmentation strategy leads to promising performance on the Kinetics-100/400, Mini-Something-v2, UCF-101, and HMDB-51 datasets in the low-label regime.
We also validate our data augmentation strategy in the fully supervised setting and demonstrate improved performance.
Results
Semi-Supervised Learning (FixMatch with 3D ResNet-18)
Semi-Supervised Learning on Mini-Something-v2 (TCL with TSM ResNet-18)
Semi-Supervised Learning on Kinetics-400 (TCL with TSM ResNet-18)
Supervised Learning (FixMatch with R(2+1)D ResNet-34)
Cross-Dataset Semi-Supervised Learning (FixMatch with R(2+1)D ResNet-34)