Feature Size Measurement of Multihole Sheet Metal Part Based on HALCON

To realize the target of having a precise feature size measurement of multihole sheet metal part, this paper based on HALCON, first calibrates the camera with HALCON's calibration assistant. After acquiring the image of the multihole sheet metal part, the image coordinates of the center of fitting ellipse and the length of the long and short half shaft (pixel unit) can be gotten by proceeding a series of operations like thresholding, subpixel-precise contour extraction, fitting ellipses and so on. At last, the point coordinates in image are transformed into the plane Z=0 of the world coordinate system through translation and rotation, and the value of each feature size of the sheet metal part can be calculated.