Abstract: Nowadays, the projection technology is in widespread use in many fields, such as teaching, conferences and lectures. However, the flip laser-pointer is the main interaction method in most projection interaction processes. It is monotonous and cannot easily obtain the mouse coordinates. In view of these problems, taking into account of the development trend of short-focus projection technique, this paper presents a laser spot mapping method based on short-focus camera. In this method, the laser spot coordinates can be accurately mapped from the projection screen to the mouse coordinates of the operating system, which provides support for laser-pointer-based short-focus projector interaction. Taking into account of the hardware integration of the short-focus camera and the short-focus projection, the proposed method collects projected images by making use of short-focus camera of ordinary resolution and the laser spot is obtained from the collected images. In addition, taking into account of the large distortion of the short-focus lens, it designs a two-stage calibration procedure, in which the second stage calibration makes up the mapping error resulted in the first stage calibration to guarantee the accuracy of the coordinate mapping. The proposed method is promising in the application of the projection interactive system based on the laser pointer.

Key words: human-computer interaction, laser spot tracking, distortion correction, coordinate mapping, secondary calibration

摘要： 在现今的教学、会议以及演讲等众多领域上，投影技术得到了越来越广泛的使用。而大部分投影交互过程中主要使用翻页激光笔等，这种方式交互操作单调，并且不能方便地获取鼠标坐标。针对这些问题，同时考虑到短焦投影技术的发展趋势，提出了一种基于短焦相机的激光笔光点坐标映射方法，将激光点坐标准确地从投影画面映射到操作系统的鼠标坐标，为基于激光笔的短焦投影交互提供了支持。该方法考虑到短焦相机与短焦投影的硬件融合，使用普通分辨率的短焦摄像头采集投影图像，从采集的图像中获取激光点。考虑到短焦镜头畸变大的特点，设计了二次标定的过程，利用第二次标定弥补第一次标定留下的误差，从而确保了坐标映射的精度。提出的方法在基于激光笔的投影交互系统中具有很好的应用前景。

关键词: 人机交互, 激光点跟踪, 畸变校正, 坐标映射, 二次标定