Augmented reality is a technique to fuse virtual and real worlds. The proposed augmented reality system aims to use an off-the-shelf web camera

and augments related virtual media information onto the Chinese-character-markers surrounded by black rectangles

which provides a new learning experience for Chinese character. The proposed method enhances the marker detection method with edge extraction

and performs well under complicated shading condition. To reliably solve the camera parameters

the proposed system first uses the homography to estimate the initial values

and then incorporates adaptive smoothness constraint to reduce the image noise. This constraint makes the solved camera parameters very accurate and stable. The experimental results demonstrate the effectiveness and robustness of the proposed system.