A camera facing the front of a vehicle while the vehicle is moving on the road may be calibrated by receiving sequential images from the camera. Image key points in the area limited by the road location are selected. The key points are tracked using an optical flow method. A filtering procedure is applied to the key points to identify the straight-line motion of the vehicle. At least two straight lines corresponding to opposite sides of the road. A calibration algorithm is applied to the at least two lines to determine a vanishing point. The pitch and/or yaw angles of the camera are then calculated.