基于双边最邻近搜索的光条中心线提取方法

A method for extracting the centerline of stripes using two-sided nearest neighbor search algorithm

线激光三维扫描系统中,灰度重心法作为光条中心线提取常用算法,具有速度快,计算简单等特点,为提高灰度重心法定位精度,往往需要计算中心线局部法线方向,而现有局部法线计算方法引入大量复杂计算,不利于算法整体性能提升。为此,提出光条双边最邻近搜索方法,实现简单、快速的局部法向计算。该方法先通过光条梯度局部极大值获取光条双边缘;再对左右双边缘采用最邻近搜索算法快速获取局部法向;最后,根据局部法向逐行进行灰度重心法计算,获取各行激光中心点亚像素坐标。实验结果显示,该方法中心线提取均方根误差为0.00496 pixel,相较于传统的Steger算法以及灰度重心法,不仅具有更好的中心线提取精度,同时也具备优秀的提取速度。

The gray gravity center method is usually used to extract the centerline of stripes in 3 D scanning system with line laser,which has the advantages of high speed and convenience calculation.In order to further improve the accuracy of gray gravity center method,the calculation of local normal direction of centerline is necessary.However,the current calculating methods introduce a large quantity of complex calculations,which is not contribute to the overall performance improvement of the method.To solve the problem of complex calculating,a two-sided nearest neighbor search method is proposed,which realizes the simple and rapid calculation of local normal direction.Firstly,the two edges of stripes can be obtained by the local maximum of gradient.Secondly,the nearest neighbor search algorithm is applied to the two edges respectively to obtain the local normal direction.Finally,the sub-pixel coordinates of the laser center point of each line can be calculated with gray-gravity method using the local normal direction.Experimental results show that the center line extraction accuracy of this method can reach 0.00496 pixel,compared with the traditional Steger algorithm and gray gravity center method,not only has better center line extraction accuracy,but also has excellent extraction speed.