Mobile Face Tracking: A Survey and Benchmark

With the rapid development of smartphones, facial analysis has been playing an increasingly important role in a multitude of mobile applications. In most scenarios, face tracking serves as a crucial first step because more often than not, a mobile application would only need to focus on analysing a specific face in a complex setting. Albeit inheriting many commons traits of the generic visual tracking problem, face tracking in mobile scenarios is characterised by a unique set of challenges. In this work, we propose iBUG MobiFace benchmark, the first mobile face tracking benchmark consisting of 50 sequences captured by smartphone users in unconstrained environments. The sequences contain a total of 50,736 frames with 46 distinct identities to be tracked. The tracking target in each sequence is selected with varying difficulties in mobile scenarios. In addition to frame by frame bounding box, the annotations of 9 sequence attributes(e.g. multiple faces) are provided. We further provide a survey of 23 state-of-the-art visual trackers and a comprehensive quantitative evaluation of these methods on the proposed benchmark. In particular, trackers from two most popular frameworks, namely, correlation filter-based tracking and deep learning-based tracking, are studied. Our experiment shows that (a) the performance of all existing generic object trackers drops significantly on the mobile face tracking scenario, suggesting the need of more research effort into mobile face tracking, and (b) the effective combination of deep learning tracking and face-related algorithms(e.g. face detection) provides the most promising basis for future developments in the field. The database, annotations and evaluation protocol/code will be made publicly available on the iBUG website.