Abstract：An automatic reading method is proposed for various types of pointer instruments captured by fixed cameras in substations. This method consists of five stages: template making, template matching, image processing, needle recognition, and geometric reading. The geometric relationship between the scale value and the angle is determined by template making. The template matching algorithm is used to locate the position of the meter panel. The image of the meter panel is extracted. The interference of light and shadow on the needle recognition is reduced by Gaussian filter and gamma transform. In order to improve the effect of image binarization in complex environment, K-means clustering algorithm is used to obtain the dynamic binarization threshold of meter panel image. In order to adapt to the round and oval deformed dial, the line segment with variable length is used to fit the needle in the binary image of the meter panel to obtain the angle of the needle, and then the reading corresponding to the angle of the needle is calculated in combination with the corresponding relationship between the angle of the main scale and the scale value. The practical application results show that for the pointer meter in the substation, this method has good robustness to the interference factors such as illumination, shadow, occlusion, inclination and deformation, and the error is less than the minimum scale interval, which meets the engineering application requirements.
2024, Vol. 25 
