Post on 02-Apr-2015
transcript
Maps, Charts andCoordinate Systems
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.
Maps
DeLorme Gazetteer - 1:65,000 to 1:400,000 1” = 1.0 miles to 6.3 miles (Scale varies by state)
Series Scale1 inch represents
approximately1 centimeter represents
World Aeronautical Chart (WAC) 1:1,000,000 16 miles 10 kilometersSectional (Aeronautical Chart) 1:500,000 8 miles 5 kilometersTerminal area chart 1:250,000 4 miles 2.5 kilometers1 degree by 2 degrees or 3 degrees 1:250,000 4 miles 2.5 kilometersJoint Use Graphics (JOG) (metric) 1:250,000 4 miles 2.5 kilometers30 by 60 minute (metric) 1:100,000 1.6 miles 1 kilometerCounty Maps (metric) 1:100,000 1.6 miles 1 kilometerAlaska Maps 1:63,360 1 mile (exact) 633.6 meters15 minute 1:62,500 1 mile 625 metersCounty Maps (metric) 1:50,000 4,166 feet 500 metersUSGS-DMA 15 minute (metric) 1:50,000 4,166 feet 500 meters7.5 minute 1:25,000 2,083 feet 250 meters7.5 minute 1:24,000 2,000 feet (exact) 240 metersPuerto Rico 7.5 minute 1:20,000 1,667 feet 200 meters
Map and Chart ScalesMap and Chart Scales
CBSAR uses this
Projecting a Sphere Onto a PlaneProjecting a Sphere Onto a Plane
Plane Projection
Cylindrical Projection Conical Projection
Types of ProjectionsTypes of Projections
Accurate Shapes
Accurate Sizes
Exaggerated Sizes Distorted Shapes
Types of ProjectionsTypes of Projections
Types of ProjectionsTypes of Projections
Meade Ranch (Clarke 1866)
Map ProjectionsMap Projections
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 CoordinatesRectangular (Cartesian) Coordinates
Latitude and longitude, and Universal Transverse Mercator are two global coordinate systems used by GPS.
Many other coordinate systems exist worldwide.
Coordinate Systems
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
Latitude & LongitudeLatitude & Longitude
0º0º
0º0º
Point of OriginPoint of Origin
Prime MeridianPrime Meridian
EquatorEquator
(Longitude)(Longitude)
(Latitude)(Latitude)
10º N10º N
30º N30º N
10º S10º S
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
Latitude
Parallels of LatitudeParallels of Latitude
10º10º
10º10º
10º10º
10º10º
690 statute 690 statute milesmiles
690 statute 690 statute milesmiles
10º S10º S
0º N0º N
10º N10º N
20º N20º N
Parallels of LatitudeParallels of Latitude
690 statute 690 statute milesmiles
Crested Butte is 38oN of the Equator
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.
Longitude
Meridians of LongitudeMeridians of Longitude
10º10º
10º10º
10º10º
110º W110º W120º W120º W
690 miles690 miles
460 miles460 miles
240 mi240 mi10º10º
Equator
Meridians of LongitudeMeridians of Longitude
Determining Latitude & LongitudeDetermining Latitude & Longitude
30º N
50º W
Equator (0º) Equator (0º)
Prime MeridianPrime Meridian(0º)(0º)30ºN, 50ºW30ºN, 50ºW
Lat/Lon CoordinatesLat/Lon Coordinates
hdddhddd00 mm’ ss.s”: N 43 mm’ ss.s”: N 430 0 40’ 40’ 55.8”55.8” X W 116 X W 1160 0 17’ 14.1”17’ 14.1”
((55.8”55.8” / 60 = .93’)) Degrees Minutes SecondsDegrees Minutes Seconds
Different coordinates representing the same location:
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.
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.
38o 47.000’
N 38o 46.8’
N 38o 46’48”
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 LongitudeLatitude and Longitude
2.5’ = 2’ 30” (x3)
2.5 minute= 2.5’ = 2’ 30” (x 3)
Grid is narrower at top than bottom
Since there are(3) 2.5’ grids
in each direction,these are called
7 1/2 minutetopos or quads
USGS1:24,000
topographicmap
It is difficult toquickly determineor even estimateposition in lat/lon
BUTaircraft operate
using lat/lon
Latitude and LongitudeWith 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 LongitudeWith 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.
e.g. N 38o 53.1’
Latitude and LongitudeWith computer & software we can add grids to make it easier
We can plot exact locations or eyeball it
Let’s practice
Answer
N 38o 53.4’
W 106o 58.4’
If you were within .1’ of the above answer, you did great!
Latitude and LongitudeLatitude and Longitude
2.5’ = 2’ 30” (x3)
2.5 minute= 2.5’ = 2’ 30” (x 3)
Grid is narrower at top than bottom
Since there are(3) 2.5’ grids
in each direction,these are called
7 1/2 minutetopos or quads
USGS1:24,000
topographicmap
It is difficult toquickly determineor even estimateposition in lat/lon
BUTaircraft operate
using lat/lon
To use our team maps, you need tools as
follows
Determining LatitudeDetermining Latitude
44º 15’ 00”
17’ 30”
2.5
minLatitude of
red square =
44º 16’ 48”
LatitudeLines
(Parallels)
LL
AA
TT
II
TT
UU
DD
EE
LO
NG
ITU
DE
7.5 min. scale 1:24,000
Determining LongitudeDetermining Longitude
Longitude of red square =
115º 19’ 00”
115º 17’ 30”20’
2.5 min
LongitudeLines
(Meridians)
LL
AA
TT
II
TT
UU
DD
EE
LONGITUDE
7.5 min. scale 1:24,000
End of Lat. & Long. Section
Next section will be UTM
Universal Transverse Mercator