# Performance Evaluation of Ground AR Anchor with WebXR Device API
## 1 Introduction  
Web eXtended Reality (WebXR) is a standard used to support the rendering of a 3D scene with appropriate hardware to present a virtual environment in a web environment or to add graphic images to the real environment. In other words, it is used to provide extended reality in a web environment. In the past, extensive studies for supporting virtual environments in a web environment have been performed, such as WebVR application programming interface (API) and WebAR API [1, 2]. However, because these APIs were developed to service a particular virtual environment, supporting other virtual environments became difficult and modifications were time-consuming. According to Mozilla, some browsers may still support Web API, but they have already been removed from the relevant web standards, are in the process of being removed, or are only being maintained for compatibility purposes [3]. Therefore, this paper used a new WebXR Device API including these APIs, and evaluated how well it performs through experiments.  
The World Wide Web Consortium (W3C) group released the Web eXtended Reality Device Application Programming Interface (WebXR Device API) in 2018. This interface allows instant deployment of extended reality services to any extended reality platform requiring only an active web browser. In addition, both augmented reality and virtual reality can be supported with minimal modifications. Moreover, large downloads are not required and users can immediately experience virtual environments on the website. For this reason, research on this interface is actively underway. However, the current version isunstable, which can cause a deviation in the anchor position when the measuring device is moved, which can reduce the stability of the anchor. When this issue occurs, the 3D model appears to be in a location other than the location specified by the user. As a result, users can be less immersed in the AR environment. Therefore, the need for research on interface performance evaluation has emerged [4].  
In this study, we aimed to evaluate the performance of the WebXR Device API and conducted a performance evaluation study. It is important to determine the user could sufficiently use the API or additional development of the API is necessary and the developer is worth investing time in the development of the API.  
The experiment was conducted in two different ground environments, and experiments were conducted after loading a 3D model through the WebXR Device API in a mobile web environment. The first experiment measures the camera trajectory in a web environment when the device moves after loading a 3D model. In the second experiment, after the 3D model is loaded, a real model with the same size and shape as the 3D model is created and placed in the same position for accuracy measurement through the difference image, mean absolute error, and match rate. The third experiment is a 3D model rendering speed measurement experiment.  
The structure of this paper is as follows. In Section 2, the background theory is explained. In Section 3, the experimental environment and experimental methods for performance evaluation are described. In Section 4, the experimental results and discussions of a performance evaluation using the proposed method are presented. Finally, Section 5 presents conclusions, limitations, and future research plans.