Introduction

Virtual Reality[1], also known as VR, is a technique to simulate a real world with comprehensive application of man-machine interact, multimedia, computer graphics etc.[2] VR technique is immersive, interactive and imaginative.[3] Immersive, indicates that virtual environment stimulate human in vision, hearing, smell, taste, touch; interactive means users have access to control and receive feedback; imaginative means users can interpret the future based on immersion and interaction. However, VR applications requires high performance on computer hardware, while actual hardware performance in user devices varies from each other. Stuck, decline in frame rate, or even crash may occur under certain circumstances, which hardly raise the awareness of developers if real-time monitoring on VR application is not realized, resulting in poor user experience and loss of potential customers. Man-machine interact in VR application is significantly different from traditional application, mainly in terms of way of observe and control:[4]
Way of observe. Traditional scene is realized via a display with fixed dimension. Users observe the scene via camera either in first person view (point of view, or POV) or third person view (God view). VR application on the contrary has no limitation from display. Users can observe the scene freely through vision. Although there’s still the concept of camera in VR, the limitation of observation resulted from camera has significantly reduced.
Way of control. Keyboards, mouse and touch screen are typical means of input in traditional man-machine interact, which is not practical in VR man-machine interact since the vision is filled with virtual world, and users have no eye contact with external input devices. It is common way that users observe the virtual world from headset equipment, and control by joystick.
In addition, thanks to the immersion of VR application, a more vivid observation and more diverse interaction can be established. As a result, analyzing user manner acts as a significant role in excavating user demand as well as improving user experience. Furthermore, flaws in VR application can be discovered and corrected by evaluating user manner, improving application quality, strengthening user stickiness and growing overall profit.[5]
Monitoring and testing on VR application receive fewer awareness compared with VR technique itself for the time being. Major performance monitoring platform in China (i.e. WeTest, Umeng, Toushibao) mainly focus on mobile game application monitoring based on Unity 3D engine in terms of application performance, user in-app purchase etc., while lack of monitoring on VR applications.[6][7] For VR application monitoring, Ghostline、Retinad VR and FishBowl VR are among the most representative teams for the time being.[8] Ghostline can monitor user interaction, body condition and fluctuation in emotion, making it feasible to discover user manner under VR environment thanks to its quantitative analysis. However, monitoring the application performance and crash issue via Ghostline is not practicable. RetinadVR, on the contrary, collects application data including location, operating environment, application performance, VR device information and so on in forms of a Unity 3D plugin, while lack of awareness of user manner. FishBowlVR applies a real-man approach. A technician is assigned to a developer under actual demand raised by developer, and a comprehensive test report can be generated based on real-man test on application.
To sum up, VR application has already possessed great variety and applied in gaming, medical, tourism etc. thanks to its immersive, interactive and imaginative. It is also promising that VR can cooperate with BIM technology, which is being more and more popular in building service industry. Design of interaction as well as choose of VR device and development tool for VR application are different from each other currently. In addition, it is difficult for developers to establish real-time monitoring on VR application performance in user hardware environment as well as user behavior in interaction due to lack of monitoring tool for VR applications.
The targets of this paper are: a) build up an interactive VR scene based on Unity 3D engine and HTC Vive device, b) design a real-time monitoring SDK tool for VR application, and simultaneously collects data in terms of hardware configuration, performance, crash and user behavior, c) design a data analysis center for processing data from monitoring SDK as well as generating monitoring report with graphs. At the end, a VR scene will be selected to verify the effectiveness of the SDK tool via carrying out real test.