基于摄像机的多投影屏幕激光笔跟随演示方法

大中型会议中心在多投影仪屏幕的演示过程中，由于主次屏幕间缺乏联系，主屏幕的激光笔光点无法显示在次屏幕，演示效果不佳。因此，提出了一种基于摄像机的多投影屏幕激光笔跟随演示方法，通过摄像机建立主投影区域和计算机显示器之间的联系，实现激光笔光点从主投影区域变换到计算机显示器，从而控制光标移动，使得次投影屏幕也有计算机光标跟随演示的效果。主要步骤包括:基于单色投影标定主投影区域相对计算机显示器的射影变换矩阵H；利用实时采集的主屏幕图像提取激光笔光点；基于射影变换矩阵H计算激光笔光点在计算机显示器的坐标，并控制计算机光标跟随到达指示位置。实验表明该跟随演示方法在计算机显示器上的横向和纵向跟随误差都在5个像素之内，可以在次屏幕中很好地跟踪激光笔光点位置，达到既解放演讲空间，又能与全体观众沟通的目的。

Demonstration method of laser pointer for multiple projection-screens based on camera

The demonstration effect is low in large conference center with multiple projector-screens, because there is no connection between the primary and secondary projector-screens, and the laser pointer on the primary screen could not been shown on the secondary screen. A demonstration method of laser pointer for multiple projection-screens based on camera is proposed in this paper. A connection between the primary projection and the computer screen is built by the camera, and then the point of the laser pointer on the primary projection can be transformed to the one on the computer screen. Based on this, the cursor can be moved and the secondary projection will have the same demonstration effect. The main steps include: (1) compute the homography matrix H between the primary projection and the computer screen by monochromatic projection. (2) extract the point of the laser pointer on the real-time captured image of primary projection. (3) calculate the indicating point on the computer screen base on homography matrix H and control the cursor move to there. Experiment shows that this method can calculate the position of the laser pointer on the computer screen with an error within 5 pixels and track the laser pointer on the secondary screen successfully. This method can both give an unlimited space to the demonstrator and a communication to all the audience.