Real-time geometric registration using feature landmark database for augmented reality applications

In the field of augmented reality, it is important to solve a geometric registration problem between real and virtual worlds. To solve this problem, many kinds of image based online camera parameter estimation methods have been proposed. As one of these methods, we have been proposed a feature landmark based camera parameter estimation method. In this method, extrinsic camera parameters are estimated from corresponding landmarks and image features. Although the method can work in large and complex environments, our previous method cannot work in real-time due to high computational cost in matching process. Additionally, initial camera parameters for the first frame must be given manually. In this study, we realize real-time and manual-initialization free camera parameter estimation based on feature landmark database. To reduce the computational cost of the matching process, the number of matching candidates is reduced by using priorities of landmarks that are determined from previously captured video sequences. Initial camera parameter for the first frame is determined by a voting scheme for the target space using matching candidates. To demonstrate the effectiveness of the proposed method, applications of landmark based real-time camera parameter estimation are demonstrated in outdoor environments.