Extraction of incoherent linear structured light stripe center on metal surface

When the metal surface profile is measured by the linear structured light method, the extraction error of stripe center is often large due to the influence of optical properties and speckle noise of metal surface. Therefore, a profile measurement method that used incoherent linear structured light was proposed, which could avoid the influence of speckle noise. A corresponding method for extracting the center of incoherent linear structured light stripe was proposed by analyzing the characteristics of metal surface profile stripe images. Firstly, the original stripe image was segmented using adaptive threshold segmentation algorithm combined with integral image principle. Then, the center coordinates of original stripe were roughly extracted by gray centroid method. The regions of interest and background of stripe image after threshold segmentation were determined by extending the roughly center to stripe width direction, and the noise in the background region was removed. Finally, the stripe center was extracted by geometric center method after median filtering. The experimental results show that the average error of incoherent light stripe center of roughness specimen surface extracted by proposed method was 1.5 μm and that of involute gear was 0.9 μm, which are both smaller than those of line laser stripes. The proposed method can accurately extract the center of incoherent linear structured light stripe on metal surface.