Turn in Lab 2
• Put your name, section, and perm number on
your answer sheet.
Lab 3: Land Navigation (1)
Yingjie Hu
Three North
• True North (N)
• Magnetic North (MN)
• Grid North (GN)
How to measure the direction
between two points?
•
•
•
•
Azimuth
Back azimuth
Bearing
Back bearing
How to describe the direction
between two points?
• Read the part 2 of the instruction file, and
figure out what are the definitions of the four
concepts. (5 minutes)
B
A
Azimuth
• The direction of two points referring to the
North.
– Magnetic Azimuth
– True Azimuth
North
A
Azimuth
B
Back Azimuth
• If forward azimuth is more than 180, back
azimuth equals forward azimuth subtract 180
• If forward azimuth is less than 180, back
azimuth equals forward azimuth plus 180
– When azimuth = 30, back azimuth?
– When azimuth = 220?
Bearing
• Another way to describe the direction of two
points.
– Baseline (N or S)
– Angle between the baseline and direction
– Direction of travel
– E.g. N30W, S18E…
Bearing
North
W
Azimuth = 120, how
about its bearing?
E
A
S60E
B
S
Back bearing
• Bearing can be calculated from azimuth
• Back bearing can be calculated from back
azimuth
• When azimuth = 30, how about back azimuth,
bearing, and back bearing?
Compass
Compass
The magnetic needle always points at
magnetic north, not the true north
How to measure azimuth on a map?
1. Orient the map (make the magnetic north of
the map in accordance with the magnetic
north of the real world)
2. Identify the direction between two points.
3. Use compass to measure the azimuth
Assignment
• This is a two-week lab. You only need to finish
part1 to part 3 this week. And you do not
need to turn in your homework next week.
• Please return the compass and map after the
class.
• If you need to draw on the map, please use
pencil and erase the drawing before returning
it.