大型结构体裂缝检测中的定位方法

为了提高大型结构体表面裂缝检测的效率,提出了一种基于图像处理技术和坐标映射相结合的定位方法。该方法首先在序列图像中抽取清晰度最高的一帧,应用Retinex算法对光照引起的亮度不均进行补偿。然后将提取的标志点图像坐标映射到观测坐标系下,根据标志点的观测坐标和世界坐标计算两坐标系间的映射关系。再根据形态学图像处理中的凸壳、像素化、细化算法提取裂缝的图像坐标;如果观测新裂缝,则将裂缝图像坐标映射到世界坐标系下;如果观测历史裂缝,则将该条裂缝的世界坐标映射到当前观测坐标系下,并计算该条历史裂缝当前的观测角度,从而实现裂缝的空间定位。经实验证明,该方法高效、准确、便捷,16 s内可实现自动定位,且偏差不大于0.07°。

Novel positioning method for detecting large structure surface cracks

For detection of large structure surface cracks, a positioning method based on image processing technology and coordinate mapping is presented. First, the highest resolution frame is extracted from the sequence images, and the Retinex algorithm is used to compensate the uneven brightness. Second, the landmark image coordinates are mapped to observation coordinates. The mapping relationship between the world coordinate system and the observation coordinate system is calculated. Third, the morphological image processing algorithm is used, such as convex hull, pixels and thinning, to extract crack image coordinates. If there is a new crack, its observation coordinate is mapped to the world coordinate. If there is an old crack, its world coordinate is mapped to the observation coordinate. The observation angle in current observation system is calcualted. The result shows that this method is efficient, accurate and convenient, and the position error is less than 0.07°in 16 seconds.