An improved identification method for hollowing instrument

Aiming at the problem that the pointer are occluded when manual inspection of hollow pointer instruments in substations and the reading error caused by shooting angle is large, a detection method of pointer segments based on annular region segmentation is proposed. This method combines the principle of Hough gradient method and adopts multi-layer template feature matching to build a table needle template library. Firstly, the image is grayed, binarized and expanded. Secondly, the tilted instrument image is corrected by perspective transformation matrix. Finally, the outline is detected by Canny algorithm, and the pixels in the annular region are detected from outside to inside until the pointer is found. In the annular area, the pointer connecting the center of the instrument and the detected annular area is the pointer position of the instrument. The results show that the pointer instrument automatic recognition system can accurately identify the reading of the pointer. Compared with the SVM method, the accuracy of the reading is higher and the false rate of detection is lower.