RESEARCH OF REGISTRATION METHOD IN VIDEO-BASED AUGMENTED REALITY

Xueling Wu ^{1, 2} , Qingyun Du², Fu Ren ²

1. China University of Geosciences, Wuhan, PRC

2. Wuhan University, Wuhan, PRC

Augmented reality (AR) is a technology of merging additional information generated from a computer model into a user’s view to enhance or augment perception of a real environment. And geographical information system (GIS) plays an important role in management and processing of spatial data which describes plane position and basis outline of spatial object. As for true representation of the real world, it is not enough. Therefore, the paper introduces AR into GIS to promote the development of outdoor AR system, and also would explore a new research direction for geographical information science. One of the key tasks for augmented reality in GIS is to make the virtual and real scene merged correctly to support user’s operation and decision.

Firstly, in most of augmented reality systems the real object is static, such as wall and architectures. While the researches pay no attention to dynamic object tracking. In order to solve this problem, the paper analyzes and compares two existing registration methods: registration of augmented reality based on a few markers points with different colors and natural characteristics to find the essential difference between those two methods. In the former, the position and orientation of identification points and video of template are given. So the transition matrix between the identification template and the image plane can be gotten. While in the latter, spatial information is introduced.

Secondly it proposes a new registration method which not only uses idea of identification point registration, but improves it to realize registration in outdoor video augmented reality, which uses a see-through head mounted display (HMD) showing the result of registration, and a single color CCD camera capturing video. Furthermore, the paper utilizes 3D compass and GPS attached on user’s body to calculate transition matrix from world coordinate system to camera coordinate system, which 3D compass provides rotation parameter through three angles including pitch, heading and roll. Simultaneously, the translational parameter is supplied by GPS receiver. And the transition relation from virtual coordinate system to world coordinate system is given.

Lastly, transition matrix from virtual coordinate system to the image plane can be calculated. Only by this, 3D virtual object generated by computer model is added into the HMD as a whole. Synthetically, video-based registration offers a superior approach to 3D registration of dynamic object. The new method significantly simplifies the registration system and coordination errors are eliminated. The method requires little computation and can be easily realized in real time. In the end, the paper discusses the further related research works, and the important significance of its development.