## 2 Related Work
### Gesture Interactions  
The user can perform either a 2D-based task, such as selecting buttons and typing texts, or a 3D-based task, such as 3D orientation and translation [21]. Therefore, offering AR smart glasses with better input metaphors makes the interaction more intuitive and efficient, which enables the user to handle more complicated and visually demanding tasks [15]. In particular, this paper describes two widely used approaches: gesture-based interaction and touch-based interaction.  
Gesture-based interaction tracks the position and orientation of the user's fingers or hands using the camera or inertial measurement unit (IMU) of the AR smart glasses and supports interactions with virtual objects in the AR environments [21; 22; 23; 24; 25; 26; 27; 28; 29; 30]. [PERSON] et al. [21] proposed WeARHand, which allows the user to manipulate virtual 3D objects with a bare hand in a wearable AR environment. [PERSON] et al. [29] proposed a system that enabled users to type on a virtual keyboard using a head-mounted AR device and hand localization derived from body-fixed sensors. Meanwhile, [PERSON] et al. [28] distilled a set of design principles for mid-air gestural interaction for smart glasses, one of which showed the potential of using an independent hand tracking device, such as a haptic glove, to form an integrated wearable system with smart glasses. Hand gesture-based interaction can support natural gestures, such as pointing and grabbing, to interact with virtual objects [15].  
In other research works, touch-based interaction has been widely used in various smart and mobile devices [31; 32; 33; 34; 35; 36]. [PERSON] et al. [33] proposed using a smartwatch as an indirect input device to make an effective smart glasses interaction method for tasks, such as text entry. [PERSON] et al. [34] proposed DigITouch, which is a touch-sensitive glove that enables thumb-to-finger interaction for eyes-free input on wearable systems. DigITouch uses thin, partially conductive fabric strips along with the fingers and a conductive patch on the thumb pad. [PERSON] et al. [35] presented PalmType, which uses palms as interactive surfaces to enable an intuitive and efficient keyboard interface for smart glasses. [PERSON] et al. [36] proposed the augmentation of accessories worn behind the ear with a device that unobtrusively instrumented the ear as an interactive surface.  
Some researchers have also evaluated interaction methods using AR smart glasses [37; 38]. [PERSON] et al. [38] found that the modes of manipulation of physical versus digital media were fundamentally different. However, previous methods have not been fully evaluated by regarding both the visual context and the interaction gesture, although both aspects may affect each other.  
Although previous research works presented various approaches to the visualization and interaction in wearable AR environments, most of them have focused on developing domain-specific applications rather than conducting comparative evaluations for user-centric task assistance concerning different types of visual augmentation. Regarding the visual context, there has been little research on evaluating task performance through the comparison between FOV and visual registration in wearable AR. In terms of the gesture interaction, further study is still needed for task assistance with combined gesture interactions in manufacturing operations. Note that some operations were effective in 2D-based tasks, such as selecting buttons, but others were useful for 3D-based tasks, such as 3D rotation and translation of virtual objects [15].  
Furthermore, although several research works have suggested new interactions, there is further room for improvement in wearable AR. Therefore, in this study, we analyzed not only the usability of the visual context but also interaction methods using AR smart glasses. Quantitative and qualitative analyses were carried out by comparing and evaluating task performance. This paper also presents a new challenge by analyzing experimental results.