Identifying universal facial emotion markers for automatic 3D facial expression recognition

Facial expressions convey human emotions as a simple and effective non-verbal communication method. Motivated by this special characteristic, facial expression recognition rapidly gains attention in social computing fields, especially in Human Computer Interaction (HCI). Identifying the optimal set of facial emotion markers is an important technique that not only reduces the feature vector dimensionality, but also impacts the recognition accuracy. In this paper, we propose a new emotion marker identification algorithm for automatic and person-independent 3D facial expression recognition system. First, we mapped the 3D face images into the 2D plane via conformal geometry to reduce the dimensionality. Then, the identification algorithm is designed to seek the best discriminative markers and the classifier parameters simultaneously by integrating three techniques viz., Differential Evolution (DE), Support Vector Machine (SVM) and Speed Up Robust Feature (SURF). The proposed system yielded an average recognition rate of 79% and outperformed the previous studies using the Bosphorus database.