Fingerspelling Recognition in the Wild with Fixed-Query based Visual Attention

We propose an end-to-end solution for recognizing fingerspelling using multi-scale attention with fixed-queries. Fingerspelling recognition in the wild gets challenging because of the multiple sub-problems involved - detecting the signing hand, tracking it across frames, and recognizing subtle variations in a hand gesture. While the current state-of-the-art handles these with external face/hand detectors, optical flow features, and iteratively refining the attention maps, our work proposes a deep learning model that takes in the RGB videos and recognizes fingerspelling with a single forward pass. Without any frame-level supervision, our proposed model learns to pay attention to informative regions in each frame, such as fingers, hand, and face, to recognize signs. Multi-scale features from these attended regions are then processed using a recurrent neural network to recognize the alphabet sequentially. We train our model using a curriculum learning strategy with simpler samples at the beginning, followed by challenging samples at a later stage. We have evaluated our approach on Chicago Fingerspelling Wild and WildPlus datasets and have achieved about 8% and 4% improvements, respectively, compared to the current state-of-the-art methods. Further analysis of our method shows that our attention mechanism is intuitive from a human perspective, and visualizing it offers useful insights into the working of the model.