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