I. Introduction
Today, we are witnessing a boom in wearable devices, such as Microsoft HoloLens, Google glass, and Vuzix M100 smart glass. These wearable devices have been widely used in many fields, such as tourist guides [1], [2], driving assistance [3], [4], medical applications [5], [6], healthcare assistance [7], [8], and fireman assistance [9]. For a more detailed introduction to first-person-view wearable devices and their applications, the reader may refer to [10]. Wearable devices need a more natural and intuitive interaction method. Hand gesture interaction is a good choice with the advantage of not being affected by noise, capable of indicating direction, and so on. For example, users can interact with wearable devices by performing static shortcut gestures.