3D facial expression recognition: A perspective on promises and challenges

This survey focuses on discrete expression classification and facial action unit recognition performed using 3D face data, possibly including a corresponding 2D texture image. Research trends to date are summarized and the limitations of current methods are discussed. The challenges towards the development of more accurate and automated 3D facial expression recognition methods are identified. We also call for standardized experimental protocols in order to draw fair and meaningful comparisons between different systems.