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
