“…In the man-made feature-based methods, multiple features including color [11,14], shape [15][16][17], edge [18,19], gradient [20], texture [21], key-points [22][23][24][25] and their fusions [26,27] have been explored. Meanwhile, some mathematical models have also been applied, such as the snake model [28], Hough transform [29], Active Contour Model [30], Fuzzy c-means [31], and Receptive field model [32]. In the work of Wang [14], a threshold filtering scheme based on Lab color space is proposed to locate the insulators in aerial images.…”