Surface density profiles of the two sample clusters (Top: Melotte 22 and Bottom: NGC 3532) and their projection distributions in the 2D celestial coordinate frame. The radii of the colored circles in the subplots are the tidal radii of the sample clusters, derived from 100 times of King model fitting. The black dashed circle in each subplot is plotted based on the mean of the tidal radii. The green dots with gray error bars represent the sample cluster member stars, with the gray error bars being the errors of the coordinates of these members. The red solid lines denote the surface density profiles of the two clusters.