introduction to remote sensing - university college dublin · 2009-06-17 · remote sensing data...

OverviewSatellite Sensors

Remote Sensing Data

Introduction to Remote Sensing

Daniel McInerney

Urban Institute Ireland,University College Dublin,

Richview Campus,Clonskeagh Drive,

Dublin 14.

16th June 2009

Daniel McInerney UII Summer School - 16.06.2009


Remote Sensing Data

Presentation Outline

1 OverviewObjectivesRemote Sensing TheorySpectral Signatures

2 Satellite SensorsOverviewSpaceborne SensorsSensor Characteristics

3 Remote Sensing DataLow Resolution DataMedium Resolution DataHigh Resolution Data



Remote Sensing Data

ObjectivesRemote Sensing TheorySpectral Signatures

Objectives of lecture

To provide a basic introduction to remote sensing

Demonstrate some types of remote sensing data

Quick RS exercise using ArcGIS 9.3



Remote Sensing Data


What is a Remote Sensing?

Simply put it is the measurement of objects/targets from adistance

Definitions... the measurement from a distance, of the spectralfeatures of the Earth’s surface and atmosphere’. (Mather,1999).

... the use of electromagnetic radiation sensors to recordimages of the environment which can be interpreted toyield useful information. (Curran, 1985).



Remote Sensing Data


Principal benefits of remote sensing

major role in observation

simultaneous monitoring with great detail and uniformity



Remote Sensing Data


Physical basis of Remote Sensing

Source - electromagnetic radiation (Sun)

Interaction with the Earths surface - amount of radiationreflected depends on object

Interaction with the atmosphere distorts and scatters light(interference)

Sensor to record



Remote Sensing Data


Electromagnetic Radiation

EMR waves transported through space at the speed oflight (c = 299,792,458 m/s)

EMR spectrum can be divided into several wavelengths(frequency) regions − visible spectrum is 400 - 700 nm

No sharp boundaries between these regions



Remote Sensing Data


EMR Spectrum



Remote Sensing Data


Beyond the visible spectrum

Infrared light (700 nm - 1mm)

Mid Infrared (1100 3000nm)

Thermal (3000 1mm [heat])

Microwave radiation (1mm 300cm)

Penetrates cloud



Remote Sensing Data


Interactions with the Earth’s surface

Incident radiation interferenceTransmissionReflectionScatteringAbsorption



Remote Sensing Data


Spectral Signatures

Specific combination of reflected & absorbed EMR atvarying wavelengths

Reflectance from objects differs due to object types

mineral / organic

roughness and structure

moisture content

Distinct spectral signatures (spectral response)(vegetation, water, soils)

Forms basis of discrimination/classification in opticalremote sensing



Remote Sensing Data


Spectral Signatures



Remote Sensing Data


Spectral Signatures - Landsat 7 ETM+



Remote Sensing Data

OverviewSpaceborne SensorsSensor Characteristics

Definition

Definition Any optical system that scans the objects orimage surface electromechanically or electronically inmore than one wavelength

Measure reflectance in atmospheric (windows)

Passive and active sensors exist

Record in digital format

Orbiting

Finite lifetimes

Differ in a number of key characteristics



Remote Sensing Data


Advantages of Spaceborne Remote Sensing

Large area coverage

Frequent and repetitive coverage of an area of interest;

Quantitative measurement of ground features usingradiometrically calibrated sensors;

Semiautomated computerised processing and analysis;

Relatively lower cost per unit area of coverage.



Remote Sensing Data


Characteristics

Swath width

Spatial Resolution

Spectral resolution

Temporal resolution



Remote Sensing Data

Low Resolution DataMedium Resolution DataHigh Resolution Data

Low Resolution Images

NOAA-AVHRR

SPOT-Vegetation

SeaWIFS



Remote Sensing Data


AVHRR



Remote Sensing Data


Medium Resolution Images

SPOT 4/5-XS

Landsat TM/ETM+

AWiFS



Remote Sensing Data


Landsat 7 ETM+



Remote Sensing Data


High Resolution Images

Quickbird

Ikonos

Chris Proba



Remote Sensing Data


Ikonos



Remote Sensing Data


Conclusion

Concluding remarksRemote Sensing is an important field in geo-scienceresearch

Mainly used for environmental applications, but also insocial science (r.f. population densities)

Myriad of sensors available for different applications

Questions, comments?


introduction to remote sensing - university college dublin · 2009-06-17 · remote sensing data...

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