为了解决不依赖于标志点的增强现实系统的环境注册问题，提出了一种基于选定模板跟踪的无标志点注册算法。该算法使用已标定的单目摄像机进行场景捕捉，通过对运动目标上的选定模板进行实时跟踪，获得每帧场景图像中的对应特征，利用透射投影变换计算运动区域的单应性约束后，再结合摄像机内参数，完成对目标的3维姿态估计，从而得到场景的3维环境注册信息。实现了一种基于该算法的无标志点的增强现实系统。介绍了系统结构和工作流程，试验结果验证了理论的正确性和系统的鲁棒性。

Environment registration is a key issue for an augmented reality (AR) system. An efficient markerless registration algorithm is introduced in this paper. The correspondences between frames are obtained in the process of tracking planar target with a fixed template. The homograph of the target can be computed with the perspective projective transformation. Combined with the intrinsic parameters of the camera, pose estimation of the region can be completed resulting in 3D registration for the system. A markerless AR system based on this algorithm is designed. The system architecture and working flow are illustrated. Experimental results demonstrate the accuracy of the theoretical analysis and the robustness of the system.