## 2 Related Work
### Human-Computer Interaction Method  
In order to make full use of the advantages of the display wall system, the researchers conducted in-depth research on the key technologies of the display wall system. Human-computer interaction methods constitute one of the important research areas for display wall systems. Although a larger display area is helpful for the visualization of data, it also brings some difficulties to human interaction. With the help of software tools such as Synergy, the cross-machine operation of keyboard and mouse can be realized, but it is difficult to use because the mouse pointer icon is too small and too sensitive. Therefore, the operation efficiency of traditional keyboard and mouse is greatly reduced on large-scale screens [20]. In order to solve this problem, researchers have proposed a variety of solutions, including using additional interactive devices, graphical information and composite interaction methods. Using additional interactive devices is an effective solution to achieve human-computer interaction, such as using personal smartphones with display wall systems [21; 22]. [PERSON] et al. designed a haptic device to assist visually impaired users in target selection during interaction with the display system [23]. However, there is still a lack of unified interfaces and standards for additional interactive devices, making it difficult to achieve cross-system use, which may bring additional learning costs. Graphical information can provide more auxiliary information for the interactive process at the software layer, and can improve the operation efficiency of users in selecting application windows and targets [24]. For example, the GIAnT system provides a rich set of visual elements to support the study of multi-user interaction behaviors on display wall  
systems [25]. Similar to the problems of additional interactive devices, there is currently a lack of unified standards for graphical information, so various types of visual information may cause confusion during user interaction. Combination interaction methods can use multiple interaction methods comprehensively. For example, the TALARIA system combines touch operation with hover operation to help users interact with objects that cannot be directly touched [26]. Combination interaction can make full use of the advantages of various interaction methods, but it also creates higher requirements for the design of combination methods. Among various human-computer interaction methods, the gesture-based interaction is very suitable for large-scale high-resolution display wall systems. For example, [PERSON] et al. implemented a gesture recognition framework that supports multiple input devices to meet different application requirements and realize the interaction with the display wall system [20]. [PERSON] et al. proposed the key technology of designing mid-air interaction [27], and further proposed a solution including an adjustable acceleration function and double-precision technical framework to improve the efficiency of mid-air pointing technology [28]. These interaction methods all need to convert the user's device-based or gesture-based interaction into the movement and operation of the mouse pointer. This research shows that different pointing techniques can effectively accomplish different tasks [29]. Based on these research results, the basic principles for designing human-computer interaction methods in display wall systems can be obtained. First, compared with traditional small-scale displays, when users interact with the display wall system, users tend to use gesture-based interactive operations with larger interactive areas. Then, if the interactive gestures used are familiar to users, it can simplify the process of learning interactive gestures [30]. Finally, the system should provide interaction techniques that do not require a lot of walking, because too much movement will cause physical fatigue and is not suitable for long-term interactive operations [1].