8 from std_msgs.msg 
import ColorRGBA
 
    9 rospy.init_node(
"tf_diff")
 
   11 src1 = rospy.get_param(
"~src1")
 
   12 src2 = rospy.get_param(
"~src2")
 
   15 pub = rospy.Publisher(
"diff_text", OverlayText)
 
   16 while not rospy.is_shutdown():
 
   18         (pos, rot) = listener.lookupTransform(src1, src2, rospy.Time(0))
 
   19         pos_diff = np.linalg.norm(pos)
 
   21         rpy = euler_from_quaternion(rot)
 
   22         rot_diff = np.linalg.norm(rpy)
 
   23         print (pos_diff, rot_diff)
 
   31         msg.font = 
"DejaVu Sans Mono" 
   32         msg.text = 
"""%s <-> %s 
   35         """ % (src1, src2, pos_diff, rot_diff)
 
   36         msg.fg_color = ColorRGBA(25 / 255.0, 1.0, 240.0 / 255.0, 1.0)
 
   37         msg.bg_color = ColorRGBA(0.0, 0.0, 0.0, 0.0)
 
   40         rospy.logerr(
"ignore error")