Abstract: Parameters of the white lines, which are around penalty area and goal area, are first detected automatically. These parameters in turn can be used to determine the camera parameters, reconstruct the soccer field, and compute the soccer players' real positions. The lines are segmented by using mathematical morphology operation, and then parameters of the lines are detected by using a refined Hough transform. Experimental results show that this method can extract the parameters of lines robustly and correctly from soccer video sequences, and can meet the requirement of camera calibration.