1. A method for camera calibration, the method comprising: detecting objects in a video sequence; obtaining feature information from the detected objects; extracting at least two groups of perspective horizontal parallel lines according to the obtained feature information; estimating at least two horizontal vanishing points according to the at least two groups of perspective horizontal parallel lines; defining a horizontal vanishing line by the at least two horizontal vanishing points; and calculating calibration parameters of a camera according to the vanishing points and/or the vanishing line.