## 5 Experiment 2
### Data Analysis and Discussion
The AR Pointer had a scaling error rate of 7.19% and an error rate of 5.77% in the conventional interface. The AR Pointer showed a higher error rate for object rotation angle error. For this reason, the same reason that caused the error of the position Euclidean distance above occurs and additionally, there is a problem in the rotation interaction method of the AR Pointer. First, subjects were unfamiliar with the archoll rotation method. Although it is a rotation method that is commonly used in mobile devices, it was felt that it was an unfamiliar interaction when manipulating an object identified through HMD while giving a feeling of direct manipulation when rotating an object in a mobile screen. Another problem is the limitation of the archoll rotation, indicating that it is not possible to directly control rotation about the z-axis in the 3D environment. For rotation in the z-axis, it is necessary to rotate the combination of the x- and y-axes or the user mustmove in the other direction. In the case of using the AR Pointer, the users naturally minimize their movement and eventually the object's rotation interaction becomes more difficult. The SUS usability test for subjective evaluation of each interface is shown in Figure 8. The AR Pointer proposed in this experiment was similar or better than the existing GaS + Wireframe interface method with respect to nine test items, especially the higher pointer scores for Q1 (M = 5.83), Q5 (M = 5.67) and Q9 (M = 5.33). Another notable point is that the Q3, Q5 and Q9 questions showed a big difference of 1.83, 1.50 and 1.50, respectively. Each of the questions was about easy to use, functions integration and confidence of the interface and the results showed that the proposed method of manipulating the AR Pointer was intuitive and easy to use. On the other hand, post-interviews conducted after the survey showed that the rotation of the AR Pointer was somewhat difficult. Since the current rotation interaction method has been a problem even with respect to the error rate, it is necessary to improve the interaction method so that it can be used more easily by users rather than restricting them to the existing mobile gesture interaction method. The NASA-TLX questionnaire conducted to determine the fatigue level of each interface is shown in Figure 9. Also, looking at the weighted score obtained through relative comparison in Table 3, performance of interface was the most important design consideration in the HMD AR environment when the participants considered it. The question in the Performance item was how well the given object was moved, rotated and scaled to the specified position. Although the difference from the GaS + Wireframe was not large, it proved that the highest score among the evaluation items was achieved and that the AR Pointer can achieve the best performance. The overall questionnaire results showed a difference of 8.61 before weighted score correction and 8.51 after correction, so we could see that the fatigue problem can be overcome by using AR Pointer in AR HMD environment. It is not intuitive, which is the biggest problem of the existing HoloLens interface and it is a very good result because we proposed our interface to solve the problems that cause user fatigue. The two major problems with the existing HoloLens interface are not being intuitive and causing user fatigue. Since we proposed the AR Pointer to solve these problems, the obtained usability test results have been encouraging. In particular, the physical demand item showed an average difference of 32.50, which indicates that the interface using the existing hand gesture can be a cause of great fatigue in the HMD environment. In an actual experiment, when using the GaS + wireframe interface, the subjects complained of frequent pain in the arm and this was the reason for the increase in completion time.