Facial Feature Point Tracking based on a Graphical Model Framework
Sabanci University Research Database
In this thesis a facial feature point tracker that can be used in applications such as human-computer interfaces, facial expression analysis systems, driver fatigue detection systems, etc. is proposed. The proposed tracker is based on a graphical model framework. The position of the facial features are tracked through video streams by incorporating statistical relations in time and the spatial relations between feature points. In many application areas, including those mentioned above, tracking is a key intermediate step that has a signi¯cant e®ect on the overall system performance. For this reason, a good practical tracking algorithm should take into account real-world phenomena such as arbitrary head movements and occlusions. Many existing algorithms track each feature point independently, and do not properly handle occlusions. This causes drifts in the case of arbitrary head movements and occlusions. By exploiting the spatial relationships between feature points, the proposed method provides robustness in a number of scenarios, including e.g. various head movements. To prevent drifts because of occlusions, a Gabor feature based occlusion detector is developed and used in the proposed method.
The performance of the proposed tracker has been evaluated on real video data under various conditions. These conditions include occluded facial gestures, low video resolution, illumination changes in the scene, in-plane head motion, and out-of-plane head motion. The proposed method has also been tested on videos recorded in a vehicle environment, in order to evaluate its performance in a practical setting. Given these results it can be concluded that the proposed method provides a general promising framework for facial feature tracking. It is a robust tracker for facial expression sequences in which there are occlusions and arbitrary head movements. The results in the vehicle environment suggest that the proposed method has the potential to be useful for tasks such as driver behavior analysis or driver fatigue detection.