Transcript Navigate, Locate, Communicate

Maps, Charts and
Coordinate Systems
Maps
A map is a two-dimensional representation of the Earth.
Maps incorporate projections and datums for accuracy.
All maps distort the earth to some extent.
When using a map with a GPS receiver, the datum and
coordinate system must match.
Map and Chart Scales
Series
Scale
World Aeronautical Chart (WAC)
Sectional (Aeronautical Chart)
Terminal area chart
1 degree by 2 degrees or 3 degrees
Joint Use Graphics (JOG) (metric)
30 by 60 minute (metric)
County Maps (metric)
Alaska Maps
15 minute
County Maps (metric)
USGS-DMA 15 minute (metric)
7.5 minute
7.5 minute
Puerto Rico 7.5 minute
1:1,000,000
1:500,000
1:250,000
1:250,000
1:250,000
1:100,000
1:100,000
1:63,360
1:62,500
1:50,000
1:50,000
1:25,000
1:24,000
1:20,000
1 inch represents
approximately
16 miles
8 miles
4 miles
4 miles
4 miles
1.6 miles
1.6 miles
1 mile (exact)
1 mile
4,166 feet
4,166 feet
2,083 feet
2,000 feet (exact)
1,667 feet
1 centimeter
represents
10 kilometers
5 kilometers
2.5 kilometers
2.5 kilometers
2.5 kilometers
1 kilometer
1 kilometer
633.6 meters
625 meters
500 meters
500 meters
250 meters
240 meters
200 meters
DeLorme Gazetteer - 1:65,000 to 1:400,000 1” = 1.0 miles to 6.3 miles
(Scale varies by state)
CBSAR uses this
Projecting a Sphere Onto a Plane
Types of Projections
Cylindrical Projection
Conical Projection
Plane Projection
Types of Projections
Accurate Shapes
Accurate Sizes
Exaggerated Sizes
Distorted Shapes
Types of Projections
Map Projections
Meade Ranch (Clarke 1866)
Coordinate Systems
All coordinate systems reference some particular set of
numbers for the size and shape of the earth (the datum).
Coordinates designate locations within a spatial reference
system (datum).
There are two types of global coordinate systems:
Angular Coordinates
Rectangular (Cartesian) Coordinates
Latitude and longitude, and Universal Transverse Mercator
are two global coordinate systems used by GPS.
Many other coordinate systems exist worldwide.
Latitude & Longitude
A spherical coordinate system that is unprojected.
Angular coordinates are perfectly suited to the spherical
surface of the earth.
Coordinates are expressed in degrees, minutes and seconds
(and variations of that).
Position coordinates are based on an angular distance from a
known reference point.
The intersection of the Prime Meridian and Equator.
Lat/long is the predominant coordinate system used for
nautical and aeronautical navigation.
Latitude & Longitude
Prime Meridian
(Longitude)
0º
0º
Equator
(Latitude)
Point of Origin
Latitude
Latitude is comprised of parallels, which are circles around
the earth paralleling the Equator.
Parallels are designated by their angle north or south of the
Equator.
The Equator is 0º latitude, and the North and South Poles
are at 90º angles from the Equator.
The linear distance between parallel lines never changes,
regardless of their position on earth.
1 minute of latitude = 1 nautical mile = 6076 feet
1 degree of latitude = 60 nautical miles = 69 statute miles
Parallels of Latitude
10º
Parallels of Latitude
20º N
10º N
0º N
10º S
o
10º
690 statute
miles
10º
690 statute
miles
10º
690 statute
miles
Crested Butte is 38 N of the Equator
Longitude
Longitude is comprised of meridians that form one-half of a
circle.
Meridians are designated by their angle west or east of the
Prime Meridian.
The Prime Meridian is designated 0º and extends from the
North Pole to the South Pole through Greenwich, England.
Meridians are angled, and do not parallel each other.
The linear distance between one degree of longitude at the
Equator is approximately 69 statute miles.
The linear distance between one degree of longitude at the
Arctic Circle is about 26 statute miles.
Meridians of Longitude
10º
Meridians of Longitude
10º
240 mi
10º
460 miles
10º
690 miles
120º W
Equator
110º W
Determining Latitude & Longitude
Prime Meridian
(0º)
30ºN, 50ºW
50º W
30º N
Equator (0º)
Lat/Lon Coordinates
Different coordinates representing the same location:
hddd0 mm’ ss.s”: N 430 40’ 55.8” X W 1160 17’ 14.1”
(55.8” / 60 = .93’)
Degrees Minutes Seconds
hddd0 mm.mmm’: N 430 40.93’ X W 1160 17.235’
(40.93’ / 60 = .682160) Degrees Decimal Minutes
hddd.ddddd0 :
N 43.682160 X W 116.287250
Decimal Degrees
Exercise
Please do this quick exercise and then go to the next slide
to see the answer.
o
38 47.000’
Here is an
actual map.
Write the
latitude point
for the top of
Round
Mountain in
both decimal
and second
format on a
piece of paper.
The answer is
on the next
slide.
N 38 46.8’
o
N 38 46’48”
o
Team Computer
The previous exercise was made on the team computer.
We added grids to make it easier for you.
The normal 2.5 grid map is more difficult to use to
estimate positions.
Following is a map similar to those found in the cache.
Latitude and Longitude
Grid is narrower at top than bottom
USGS
1:24,000
topographic
2.5’ = 2’ 30” (x3)
map
Since there are
(3) 2.5’ grids
in each direction,
these are called
7 1/2 minute
topos or quads
It is difficult to
quickly determine
or even estimate
position in lat/lon
BUT
aircraft operate
using lat/lon
2.5 minute= 2.5’ = 2’ 30” (x 3)
Latitude and Longitude
With computer & software we
can add grids to make it easier
We can plot exact locations or
eyeball it
Let’s practice
Go to next slide
Latitude and Longitude
With computer & software we
can add grids to make it easier
We can plot exact locations or
eyeball it
Let’s practice
Write down the Lat. &
Long. of the intersection
of the two roads. Only do
it to 1/10 of a minute
accuracy.
o
e.g. N 38 53.1’
Latitude and Longitude
With computer & software we
can add grids to make it easier
We can plot exact locations or
eyeball it
Let’s practice
Answer
o
N 38 53.4’
o
W 106 58.4’
If you were within .1’ of the
above answer, you did great!
Latitude and Longitude
Grid is narrower at top than bottom
USGS
1:24,000
topographic
2.5’ = 2’ 30” (x3)
map
Since there are
(3) 2.5’ grids
in each direction,
these are called
7 1/2 minute
topos or quads
It is difficult to
quickly determine
or even estimate
position in lat/lon
BUT
aircraft operate
using lat/lon
To use our team maps,
you need tools as
follows
2.5 minute= 2.5’ = 2’ 30” (x 3)
Determining Latitude
L
A
I
Latitude of
red square =
Latitude
Lines
(Parallels)
U
D
E
7.5 min. scale 1:24,000
44º 16’ 48”
2.5 min
T
LONGITUDE
T
17’ 30”
44º 15’ 00”
Determining Longitude
Longitude of
red square =
115º 19’ 00”
Longitude
Lines
(Meridians)
2.5 min
20’
115º 17’ 30”
End of Lat. & Long. Section
Next section will be UTM
Universal Transverse Mercator