Types of Maps & Remote Sensing

Biblical Reference

As the men started on their way to map out the land, Joshua instructed them, “Go and make a survey of the land and write a description of it. Then return to me, and I will cast lots for you here at Shiloh in the presence of the Lord.”

Joshua 18:8

Projections• Cartographers use projections to make

maps.– A projection is made by transferring points

and lines on a globe’s surface onto a piece of paper.

• There are three main types of projections:

Gnomonic Conic Mercator

Mercator Projections• A Mercator Projection is a map that has

parallel lines of latitude and longitude.– It clearly indicates direction in straight lines.– It distorts areas near the poles.– It is used for ship and plane navigation.

o Total area of Greenland = 836,300 square miles

o Total area of the U.S. =

3,806,000 square miles

Conic Projections• A Conic Projection is made

by projecting points and lines from a globe onto a cone.

– It has a high degree of accuracy for limited areas.

– It is used to make road and weather maps.

Gnomonic Projections• A Gnomonic Projection is created by

projecting points and lines on a globe onto a piece of paper that touches the globe a single point.

– It is most useful for navigation for planning a long travel route.

Topographic Maps• Topographic maps are detailed maps

that use contour lines, symbols and colors to represent changes in elevation and features on the Earth’s surface.

– A contour line connects points of equal elevation.

– The difference in elevation between two side-by-side contour lines is a contour interval.

Topographic Maps• Index contours are numbered contour lines

to indicate elevation.

• Depression contour lines have short lines at right angles to the contour line to indicate a change in the elevation direction.

Geologic Maps• A geologic

map shows the distribution, arrangement and type of rocks located below the soil.– It may also

show geologic features, such as fault lines.

Three-Dimensional Maps• Computers are often used to digitize features

such as rivers, mountains, valley and hills in order to create three-dimensional maps.

Map Legends• A map legend explains

what the symbols on a map represent.

• Symbols can represent:– Physical features (lakes,

rivers or contours)

– Roadways (interstates, highways, railroads)

– Populated areas (city sizes, state capitals)

Map Scales• A map scale is a ratio between the distance

on a map and the actual distance.– Graphic scales, the most common, are lines that

represent certain distances.

– Verbal scales are statements used to express distance (“One centimeter equals one kilometer”)

– Fractional scales express distance as a ratio between two units of the same type (1:1000 km).

Maps

A. 1:20,000 milesB. 1:40,000 milesC. 1:60,000 milesD. 1:80,000 miles

Which fractional scale represents the large actual distance?

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A. Different surface temperaturesB. Different types of rock formationsC. Different geologic terrainD. Different elevations

What do different colors on a geologic map represent?

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A. NeverB. At a mountain topC. At a valleyD. At sea level

When do contour lines cross?

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Gaspard Felix Tournachon

Remote Sensing• In Remote Sensing instruments mounted on

aircraft, satellites or balloons gather data about Earth.

• Landsat satellites record reflected visible and IR wavelengths from Earth’s surface.

– A computer converts the data into digital images.

– Landsat data are also used to study Earth’s plate movements, rivers, earthquakes and pollution.

Landsat 6• Landsat 6 was launched October 5, 1993

aboard a Titan II launch vehicle.• It failed to reach orbit due to a ruptured

fuel line.

TOPEX/Poseidon• The TOPEX/Poseidon satellite uses radar

to map seafloor features.– It transmits high frequency signals to the

ocean floor.– A receiving device picks up the reflected

echo.– The distance is calculated using the known

speed of light (through air and sea water) and the time it takes for the round trip.

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TOPEX/Poseidon• Scientists also use TOPEX/Poseidon to

estimate global sea levels, and to study tidal changes and global ocean currents.

How do satellites help study Earth?

Sea Beam• Sea Beam technology uses Sonar (sound

waves) to map the ocean floor from a ship.– A sound wave is sent from a ship to the ocean

floor.– A receiver on the ship picks up the echo.– Similar to satellite imaging, a computer calculates

the distance based upon the known speed of sound through seawater and the travel time.

– Sea Beam technology is used by fishing fleets, deep-sea drilling operations, oceanographers, volcanologists, and archaeologists.

Global Positioning System (GPS)• GPS is a satellite navigation system that

enables users to locate their approximate Earth location.– These satellites can also relay information to

a GPS receiver about elevation, direction of movement and speed.

– GPS technology is used extensively in plane and ship navigation, and to help people find a destination or determine their current location.

GPS IIR

The Geographic Information System (GIS)

• GIS uses a worldwide database to create layers, or “themes” of information that can be placed one on top of another to create a comprehensive map.

– GIS map layers remain linked to the original source so that if the original information changes, the GIS layers also change.

– Thus, the map will always be up-to-date.

Visualizing GPS Satellites• GPS receivers detect signals from the 27

GPS satellites orbiting Earth.– Using signals from at least three satellites, the

receiver calculates the location within 10 m using a technique called triangulation.

A. OneB. TwoC. ThreeD. Four

At least how many GPS satellites are needed to fix a location?

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A. Speed and time of the echoB. Wavelength and time of the echoC. Power and speed of the echoD. Time and power of the echo

A radar signal is sent from a satellite to the ocean’s surface. What information is needed to calculate distance from the return echo?

Pop Quiz

A. The Titan II launch vehicle blew up.B. A fuel line ruptured.C. The solar array wouldn’t deploy.D. Someone in the control room sent the wrong

command.

Why did Landsat 6 fail to reach orbit?

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