def get_scale(W, H, scale):
    """
    Computes the scales for bird-eye view image

    Parameters
    ----------
    W    : int
           Polygon ROI width
    H    : int
           Polygon ROI height
    scale: list
           [height, width]
    """

    dis_w = int(scale[1])
    dis_h = int(scale[0])
    
    return float(dis_w/W),float(dis_h/H)