基于形状先验活动轮廓的焊接图像熔池分割方法  

Weld pool image segmentation method based on active contour using shape priori

作　　者：罗祥[1] 王宗义[1] 褚慧慧 刘富强 

机构地区：[1]哈尔滨工程大学自动化学院,哈尔滨150001

出　　处：《焊接学报》2017年第11期113-118,共6页Transactions of The China Welding Institution

摘　　要：焊接熔池与弧光距离最近,受到的干扰最严重,导致熔池图像分割十分困难.文中提出了一种极坐标下基于凸形形状先验和边缘候选点的活动轮廓模型.首先,使用灰度和梯度极值相结合的方法获得熔池边缘候选点;然后,基于边缘候选点的位置信息,以及极坐标下轮廓顶点组成的内角信息构造活动轮廓模型的边缘能量项及形状能量项;最后,使用贪婪算法获得了最小能量轮廓顶点,使用三次B样条插值获得了光滑封闭的熔池轮廓.结果表明,提出的活动轮廓模型对初始轮廓不敏感,可以获得精度较高的熔池分割结果,能够克服弧光等噪声的干扰.Since the weld pool is near from the weld arc light,which causes a lot of interferences,it is difficult to segment the weld pool image. This paper presents an active contour model based on the convex shape priori and contour candidate points,in polar coordinates. Firstly,weld pool contour candidate points are obtained by combination of gray extreme value and gradient extreme value. Secondly,set up the edge energy term and shape energy term of the active contour model by using the position information of the contour candidate points,and the interior angle information of contour vertex in polar coordinates. Finally,find the contour vertex with minimum energy by using greedy algorithm,and the smooth and closed weld pool contour can be obtained by cubic spline. The result shows that active contour model is not sensitive to the initial contour. At the same time,it can overcome the interference of arc and other noises,and get highprecision weld pool segmentation result. Since the nearest distance between welding arc and weld pool,the arc interference is severe in the weld pool region of the image which leads to the difficulty of the weld pool image segmentation. To achieve an accurate image segmentation of the weld pool,this paper presents a polar coordinate active contour model based on convex shape priori. Firstly,the brightness and gradient distribution of the weld pool edge is analyzed,the edge candidate points is obtained by combining gray and gradient extreme points features,this method is able to locate the edge of the weld pool accurately and realize the weak edge location. Then,edge energy of the active contour model is configured based on the location information of the edge candidate points,shape energy is configured based on the inter-nal angle information of the contour vertices. Finally,minimum overall energy contour vertices are gotten by using a greedy algorithm,and a smooth closed weld pool contour is gained by using a cubic B-spline interpolation. Experimental results show that the active contour mode

关 键 词：焊接图像 熔池分割 形状先验 活动轮廓模型 

分 类 号：TG409[金属学及工艺—焊接]