Introduction to Remote SensingIntroduction to Remote Sensing Example Applications and Principles

Exploring Images with MultiSpecExploring Images with MultiSpec User Interface and Band Combinations

Questions…Questions…

DefinitionsDefinitions

Lillesand and Kiefer (1994)Lillesand and Kiefer (1994) – ““The science and art The science and art of obtaining information …acquired by a of obtaining information …acquired by a device that is not in contact with the device that is not in contact with the object…object…””

CCRS GlossaryCCRS Glossary – “A group of techniques for A group of techniques for collecting image or other forms of datacollecting image or other forms of data … … from measurements made at a distance from measurements made at a distance from the object, from the object, and the processing and and the processing and analysis of the dataanalysis of the data.”.”

Examples of Remotely Sensed DataExamples of Remotely Sensed Data

Weather Ocean Properties Physical Geography Major Disturbance Events / Hazards Cultural Features – urban mapping Many other examples – thematic info

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disturbance

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From Lillesand and Kiefer (1994)

Decision

Decision

From Lillesand and Kiefer (1994)

From Lillesand Kiefer (1994)

An Electromagnetic Wave

ll = wavelength = wavelength

nn = frequency = frequencyc = velocity of lightc = velocity of light

OO33 absorption absorption at 0.2 at 0.2 uumm

HH22O absorption O absorption at 1.4, 1.6, and 1.9 at 1.4, 1.6, and 1.9 uumm

COCO22 absorption absorption at 2.0 at 2.0 uumm

CHCH44 absorption absorption at 2.2 – 2.5 at 2.2 – 2.5 uumm

Human eyeHuman eye

Incident EnergyIncident Energy Reflected EnergyReflected Energy

E(E(ll))ii – [ E( – [ E(ll))aa + E( + E(ll))t t ] = E] = Err((l)l)

Rayleigh ScatteringRayleigh Scattering

Rayleigh Scattering as a Function of Wavelength

0

5

10

15

20

25

30

35

40

45

0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8

Micrometers (um)

Rel

ativ

e In

ten

sity

of

Sca

tter

ing

Atmospheric InteractionsAtmospheric Interactions

Types of Satellite OrbitsTypes of Satellite Orbits

Geostationary – 35,790 km above the EarthGeostationary – 35,790 km above the Earth

Sun-synchronous or “Polar”– between 700 and 800 Sun-synchronous or “Polar”– between 700 and 800 km above the Earthkm above the Earth

Satellite Orbits

http://science.nasa.gov/Realtime/jtrack/3d/JTrack3D.htmlhttp://science.nasa.gov/Realtime/jtrack/3d/JTrack3D.html

““Resolution” in Remote SensingResolution” in Remote Sensing

Four typesFour types

1)1) SpatialSpatial –the ground coverage / pixel –the ground coverage / pixel

2) 2) SpectralSpectral – area and subdivision of the EM spectrum – area and subdivision of the EM spectrum

3) 3) TemporalTemporal – frequency of coverage – frequency of coverage

4)4) RadiometricRadiometric – sensitivity to changes in energy intensity – sensitivity to changes in energy intensity

Issues of spatial & temporal scale Issues of spatial & temporal scale of the sensor platformof the sensor platform

--SPATIAL-SPATIAL-

““grain” and “extent”grain” and “extent”

‘‘Pixel’Pixel’

-TEMPORAL--TEMPORAL-

Frequency of imagingFrequency of imaging

September 15September 15 September 30September 30

October 15October 15 October 30October 30

Color Theory and Band CombinationsColor Theory and Band Combinations

AdditiveAdditive colors vs. colors vs. SubtractiveSubtractive colors colors

‘‘Natural’ and ‘False’ color compositesNatural’ and ‘False’ color composites

Displaying images, extracting informationDisplaying images, extracting information

Additive PrimariesAdditive Primaries

Subtractive PrimariesSubtractive Primaries

No single primary can be formed by No single primary can be formed by mixture of other twomixture of other two

All other colors can be formed by All other colors can be formed by mixtures of additivesmixtures of additives

Representations of color via Representations of color via pigments and dyespigments and dyes

Yellow absorbs blue, cyan absorbs Yellow absorbs blue, cyan absorbs red, magenta absorbs greenred, magenta absorbs green

Blue (0.45 um) Green (0.55 um) Red (0.65 um)

Blue (0.45 um) Green (0.55 um) Red (0.65 um)

Green = 2.5 x

Red = x Blue = x

Feb. 14, 2006 MODIS Terra, Eastern US

Snow Vs. Clouds

Clouds scatterat all wavelengths

Snow absorbs at >1.4 m

Snow Vs. Clouds

Clouds scatterat all wavelengths

Snow absorbs at >1.4 m

c

Natural Color Natural Color 33,,22,1,1

Color IR Color IR 44,,33,2,2

False Color False Color 55,,44,3,3

MultiSpec RS SoftwareMultiSpec RS Software

Research and educationResearch and education Long period development and refinementLong period development and refinement Freely availableFreely available Supported by tutorialsSupported by tutorials

http://cobweb.ecn.purdue.edu/~biehl/MultiSpec/http://cobweb.ecn.purdue.edu/~biehl/MultiSpec/