Abstract: Image based fire detection system is one of the most important factors of MSA（Multi-Step-Alarm） fire warning system，in which the precise location of fire is one of the most important missions.By the reasons of practical application such as allocation of monitor，the parameter of the transformation is difficult to get.In this paper，a method of perspective projection transform based on double vanishing point is proposed，which is able to transform image coordinate into world coordinate by analyzing the locations of four control points.Experiment results show the method is reliable and valid.

Key words: Multi-Step-Alarm（MSA）, double vanishing point, perspective projection rectification

摘要： 图像型火灾探测系统是MSA（Multi-Step-Alarm）火灾系统中的重要环节，其重要任务之一是对监控场景中的火源进行精确定位。而在实际应用中，由于安装等因素的原因，要获取摄像机的图像坐标系与世界坐标系之间转换的关键参数非常困难。提出了一种基于双灭点的图像透视投影的坐标转换方法，该方法通过分析世界坐标系中4个点在图像坐标系中的位置关系，可以实现图像坐标系与世界坐标系之间的转换。实验结果证明该方法简便实用。

关键词: MSA火灾报警系统, 双灭点, 透视校正