Fundamentals of Remote Sensing

Gathering information without physical contact

Can you sense things remotely?

Remote sensing may be accomplished in any of several

ways

A LOT further away

Further away

Close upCaroline Wicks

Organic content of soil

LIGHT COLOR WHITE BACKGROUND

(WB)

SOIL 1 % SOIL 1(SOIL 1/WB)*100

SOIL 2 % SOIL 2(SOIL 2/WB)*100

RED

DEEP RED

IR 1

IR 2

IR 3

IR 4

1. Take a set of readings on the white background2. Take a set of readings of Soil Sample 13. Divide Soil readings by white readings and multiply by 1004. Repeat with Soil Sample 25. Graph your percentages vs. wavelength

% Reflectance at Different Wavelengths of Light

0

10

20

30

40

50

60

70

700 750 800 850 900 950

Wavelength (nm)

% R

efle

ctan

ce

1. Graph percent reflectance of soil 1 vs. wavelength. 2. Connect points with a solid line.3. Graph percent reflectance of soil 2 vs. wavelength.4. Connect points with a dotted line.5. Make a legend.

Soils rich in organics have lower reflectances

So, why can’t we just use our eyes?

• Oil or Algae? • How do you know?

They don’t tell the whole story!

Oil Spill Red Tide(Algal Bloom)

400 500 600 700 800 900 10000

10

20

30

40

50

60

70

80

90

% Reflectance at Different Wavelengths of Light

% Reflectance Spinach % Reflectance Cabbage

Wavelength (nm)

% R

efle

ctan

ce

Polar Orbiting Earth SatellitePOES

Geostationary Orbiting Earth Satellites(GOES)

POES

GOES

Photo: ESA

Electromagnetic Energy

SeaWiFS Instrument Package

• Sea-viewing Wide Field of view Satellite

• Carried on the satellite “Seastar”

• Senses visible and NIR (near infra-red)

• Ocean Color

TOPEX/Poseidon

Jason

RADAR = RAdio Detection And Ranging

Satellite Altimetry

TOPEX/POSEIDON

AVHRR AdVanced High Resolution Radiometer

True-Color Imagery

Land

Water

Clouds

Chesapeake Bay

Stream Sediments

Brazil

Rainforest

Ex-Rainforest

Try interpreting some satellite images

Try interpreting some satellite images

TemperatureA

BB

A

432

5 6 7 8

20 21

2022

27

2826

26

1

28 32

3028

Recording Grid

1 2 3 4

8 7 6 5

9

13 14 15 16

12 11 10

20 21

2022

27

2826

26

28 32

3028

Using the IR Thermometer

• DO NOT point the thermometer at another person.

• Point at target and pull trigger. • Release and record the temperature in the

appropriate spot on the recording grid.• Record about 4 temperatures per grid

area.• Return to your seat and “color” mapping

grid. Be sure to include a legend of colors.

Transpiration cools leaves

RADARSAT uses microwaves

Passive or Active?

Passive or Active?

Remote Sensing Techniques Continuing to Evolve