map projections and map scales

Map Projections and Map Scales

Map Projections• The way of showing a round Earth on a flat piece of

paper– All maps have distortion– The larger the map, the greater the distortion.

Three Types of Projections1. Cylindrical– Easy to use– Latitude and longitude are

at right angles– Shows true direction– Distorts high latitudes

2. Planar– Useful for showing polar

regions– Distorts direction and

distance

3. Conic– Good for showing a small

area accurately

Map Scales

• Shows the relationship of the distance on a map to the distance on the Earth.

• There are Three types:– Graphic– Verbal– Representative Fraction

• Shows the equivalent number of units on the map to units on the real Earth

• The Representative Fraction shown above means that 1 unit on the map equals 100,000 units on the Earth (the units are inches unless specified otherwise)

Converting Representative Fraction Scales from inches to feet to miles

• Scale 1:100,000 or 1/100,0001. Inches feet: Divide 100,000

inches by 12 (there are 12 inches in a foot)

2. Your Answer should be 8333 feet.3. Feet miles: Divide 8333 feet by

5,280 (there are 5,280 feet in one mile)

4. Your answer should be 1.58 miles.

5. So, this means that 1 inch on the map equals 1.58 miles on the ground.

Now You Try:1. 1:24,0002. 1:56,7003. 1:63,360

Answers to Problems1. 1:24,000– Inches feet: 2000 feet– Feet miles: 0.38 miles

2. 1:56,700– Inches feet: 4,725 feet– Feet miles: 0.90 miles

3. 1:63,360– Inches feet: 5,280 feet– Feet miles: 1 mile