2D Wasserstein Loss for Robust Facial Landmark Detection
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Facial landmark detection is an important preprocessing task for most applications related to face analysis. In recent years, the performance of facial landmark detection has been significantly improved by using deep Convolutional Neural Networks (CNNs), especially the Heatmap Regression Models (HRMs). Although their performance on common benchmark datasets have reached a high level, the robustness of these models still remains a challenging problem in the practical use under more noisy conditions of realistic environments. Contrary to most existing work focusing on the design of new models, we argue that improving the robustness requires rethinking many other aspects, including the use of datasets, the format of landmark annotation, the evaluation metric as well as the training and detection algorithm itself. In this paper, we propose a novel method for robust facial landmark detection using a loss function based on the 2D Wasserstein distance combined with a new landmark coordinate sampling relying on the barycenter of the individual propability distributions. The most intriguing fact of our method is that it can be plugged-and-play on most state-of-the-art HRMs with neither additional complexity nor structural modifications of the models. Further, with the large performance increase of state-of-the-art deep CNN models, we found that current evaluation metrics can no longer fully reflect the robustness of these models. Therefore, we propose several improvements on the standard evaluation protocol. Extensive experimental results on both traditional evaluation metrics and our evaluation metrics demonstrate that our approach significantly improves the robustness of state-of-the-art facial landmark detection models.
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