Image segmentation algorithm for location of laser spots during aircraft relative attitude determination

An image segmentation method is proposed to locate the position of laser spots reflected by corner-cube array during relative attitude determination between aircrafts. First, the laser spots image acquired by CCD camera is transformed to a grayscale gradient distribution image by the Roberts operator. Then the image is divided into several small pieces according to the distribution of both energy and grayscale gradient. Each piece is segmented based on watershed algorithm individually to detect the margin of laser spots. Seeds of watershed segmentation are selected by using prior knowledge of appearance and energy of laser spots predicted when the laser measure system is designed. A binary image which contains the edge information of the laser spots is acquired after all segmented pieces is merged together. Then expansion and erosion algorithm is used to reduce the effect of over segmentation. The method can effectively remove the system noise or the disturbance brought by the reflection of the other optical antenna near the corner-cube array on the client terminal. Experimental results indicate that location of laser spots calculated by centric method is exactly limited in the anticipated area. The uncertainty of the center location is no more than 1 pixel.

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