基于机器视觉的柱状标签拼接算法研究

Cylindrical Label Stitching Algorithm Based on Machine Vision

中文关键词: 柱面标签  模糊隶属度函数  图像拼接

英文关键词: cylindrical label  fuzzy membership function  image stitching

中文摘要:

      目的 针对标签检测中因单目相机视野受限无法获取标签全部有效信息的问题，设计一种基于圆柱体拟合的柱状标签展开算法。方法 首先由相机标定得到的相机外参数拟合出标签圆柱体理想位姿，并确定柱面标签展开图的高度。依据圆柱体在相机视野下的极限位置确定模糊隶属度函数，筛选提取到的柱面标签边缘点。最后根据边缘点的世界坐标确定真实圆柱体的位置，提取单目相机图像中的像素值并且为标签平面展开图中对应点赋值，最终得到柱状标签的平面展开图。如果对拼接质量有着较高的要求，可以采用NCC匹配算法对拼接图像进行调整，以达到更好的效果。结果 该方法可以对多幅柱面标签图像实现快速拼接，最终得到柱面标签的平面展开图，半径30 mm的柱面标签图像拼接速度可达83.8 ms，为标签质量在线检测奠定了基础。结论 该方法能够快速且精确地将柱状产品侧面标签平面展开。

英文摘要:

      The work aims to design a cylindrical label unwrapping algorithm based on cylinder fitting to solve the problem that the monocular camera can not obtain all the valid information of the label during detection due to limited field of view. Firstly, the ideal position of the cylindrical label was fitted from the external parameters of the camera obtained from the camera calibration, and the height of the cylindrical label unwrapping image was determined. The fuzzy membership function was determined according to the extreme position of the cylinder in the field of view of the camera, and the edge points of the extracted cylindrical label were filtered. Finally, the position of the cylindrical product was determined according to the world coordinates of the edge points. Pixel values were extracted from monocular camera image and assigned to corresponding points in the cylindrical label unwrapping image, and finally, the label unwrapping image was obtained. If there were high requirements on the quality of stitching, the NCC matching algorithm could be used to adjust the stitched image to achieve better results. This method could achieve the rapid stitching of multiple cylindrical label images and the label unwrapping image was obtained. The cylindrical label image of a radius of about 30 mm could be stitched at a speed of 110 ms, which laid the foundation for online detection of label quality. This method can quickly and accurately unwrap the side label of cylindrical product.