rs 0 introductionnceg.uop.edu.pk/workshop-17to31mar-05/slides/day3/... · 0.3 to 0.4 µm...

Remote Sensing - Introduction

GROUND TRUTH

Platforms with Sensor on board

GMS(Geostationary Satellite)

LOW&MIDDLEALTITUDE AIRPLANE

LANDSAT, MOS,SPOT

SPACE SHUTTLE

HIGH ALTITUDEJETPLANE

emission

reflection

atmosphere

object

Illumination


Contents - Introduction to RS

• Principles of Remote Sensing– electromagnetic radiation

– atmospheric interaction

– surface reflection

• Remote Sensing systems– Platforms

– Sensors

– Resolution: spatial, spectral, temporal

• Applications of Remote Sensing


Definition of Remote Sensing

Remote Sensing is a method to acquire information about material objects, areas, or phenomenon through the analysis of data acquired by a device from measurements made at a distance, without coming into physical contact with the objects, areas, or phenomena under investigation.


Why Remote Sensing?


Why Remote Sensing?

• To recognize macro-patterns which may not be visible from ground

• To gain an OVERVIEW of an area

• To gather information on large areas in short time

• To gather information cost-effectively

• To gather information on inaccessible places

• To replace conventional sources of information (topo sheets, census data etc.)


What is Remote Sensing?

We acquire much information about our surrounding through the senses of sight and hearing which do not require close contact between the sensing organs and the external objects. In another word, we are performing Remote Sensing all the time.

Earth from Space

Generally, Remote sensing refers to the activities of recording/ observing/ perceiving (sensing) objects or events at far away (remote) places.


How does Remote Sensing Work?

The characteristics of an object can be determined, using reflected or emitted electro-magnetic radiation, from the object. Each object has a unique and different characteristics of reflection or emission if the type of object or the environmental condition is different. .

Electro-magnetic radiation which is reflected or emitted from an object is the usual source of remote sensing data. A device to detect the electro-magnetic radiation reflected or emitted from an object is called a "remote sensor" or "sensor". Cameras or scanners are examples of remote sensors. A vehicle to carry the sensor is called a "platform". Aircraft or satellites are used as platforms.


Principles of RS: EMR

• The definition of RS implies the use of medium which carries the information from the object to the sensor

• Usually, electro-magnetic radiation (EMR) is being used as medium

• In passive RS, the radiation emitted by some other source is being used

• In active RS, the radiation is being emitted by the system itself


Electro-Magnetic Radiation (EMR) / 2

λ (wave length)

elec

tric

fie

ld

mag

netic

fiel

d

travelling direction


Microwave bands W V O Ka K Ku X C S L P

Ultra Violet Near Infra-redShort Wave Infra-red

Inter-mediate Infra-red

Thermal Infra-red

vIolet

blue

green

yellow

orange

red

wavelength (µm) 0.4 0.6 0.8 1 5 7 10

0.3 (cm) 1 3 10 30 100

Wavelength: 0.1nm 10nm 1µm 100µm 10mm 1m 100m 10km

γ -ray X-ray UV Vis. Infrared EHF SHF UHF VHF MF LF VLF

The Electro-Magnetic Spectrum

Microwaves

Radio waves

Visible Light


Characteristics of spectral regionsRegion Wavelength RemarksGamma Ray <0.03 nm Incoming radiation is completely absorbed by the upper atmosphere

and is not available for remote sensing.X-ray 0.03 to 3.0 nm Completely absorbed by the atmosphere. Not employed in remote

sensing.Ultraviolet 0.03 to 0.4 µm In-coming wavelengths less than 0.3µm are completely absorbed by

ozone in the upper atmosphere.PhotographicUV band

0.3 to 0.4 µm Transmitted through the atmosphere. Detectable with film and photo-detectors, but atmospheric scattering is severe.

Visible 0.4 to 0.7 µm Imaged with film and photo-detectors. Includes the reflected energypeak of earth at 0.5µm.

Infrared 0.7 to 100 µm Interaction with matter varies with wavelength. Atmospherictransmission windows are separated by absorption bands.

Reflected IRband

0.7 to 3.0 µm Reflected solar radiation that contains no information about thermalproperties of materials. The band from 0.7 to 0.9µm is detectablewith film and is called the photographic IR band.

Thermal IRband

3 to 5 µm8 to 14µm

Principal atmospheric windows in the thermal region. Images atthese wavelengths are acquired by optical-mechanical scanners andspecial videocon systems, but not by film.

Microwave 0.1 to 30cm Longer wavelengths can penetrate clouds, fog, and rain. Imagesmay be acquired in the active or passive mode.

Radar 0.1 to 30 cm Active form of microwave remote sensing. Radar images areacquired at various wavelength bands.

Radio >30 cm Longest wavelength portion of the electro-magnetic spectrum. Someclassified radar with very long wavelength operate in this region.


• Makes use of sensors that detect the reflected or emitted electro-magnetic radiation from natural sources, most notably the sun.

• Due to its surface temperature of 5800K, the sun emits most of its energy in the visible part of the spectrum.

• The earth with a surface temperature of 300K emits most of its energy in the thermal part of the spectrum.


Figure (3c) Common Remote Sensing Systems

Figure (3b)Atmospheric Transmittance

Figure (3a)Energy Source

Therm al Scanners

Spectral emission, atmospheric transmittance and sensor sensitivity


Atmospheric Transmittance


Interaction between EMR and surfaces


Spectral Reflectance Curves


Chlorophyllabsorption

Water absorption

Vegetation reflectance curves


Mineral Reflectance curves


Visual

QuantitativeUsers

Sensor systems Data products Interpretationprocedures

Informationproducts

Referencedata

Pictorial

Numerical

DATA ACQUISITION DATA ANALYSIS

Re-transmissionthrough atmosphere

Remote Sensing Systems

Sources ofenergy

Propagationthrough

atmosphere

Reflection on surface features


Platform Altitude Observation Remarks

geostationary satellite 36,000km fixed point observation GMS

circular orbit satellite(earth observation)

500km -1,000km

regular observation LANDSAT, SPOT,MOS, etc

space shuttle 240km - 350km irregular observations

radio - sound 100m - 100km various investigations(meteorological, etc)

high altitude jet-plane 10km -12km reconnaissance, wide areainvestigations

low or mid altitude plane 500m - 8,000m various aero investigation surveys

helicopter 100m- 2,000m various aero investigation surveys

radio-controlled plane below 500m various aero investigation surveys aeroplane,

hang-plane 50 - 500m various aero investigation surveys hangglider

hang-balloon 800m - various investigations

cable 10 - 40m archaeological investigations

crane car 5 - 50m close range surveys

ground measurementcar

0 - 30m ground truth cherry picker

Platforms


Equator crossing: 9:45am(Local time)

ORBIT PERIOD = 98.9 MINUTES

GROUND TRACK

INCLINATION = 98.2O

DIRECTION OF TRAVEL

ALTITUDE = 705 KM(Nominal)

Earth Observation Satellite Orbits


Earth Observation Satellite Orbits / 2


Sensors

A sensor or ‘remote sensor’ is a device

to detect the electro-magnetic radiation

reflected or emitted from an object.

Cameras or scanners are examples of

remote sensing-sensors.


Sensors: Solid State Scanners


Sensors: Opto-Mechanical Scanner


In general, resolution is defined as the ability of an entire

remote-sensing system, including lens, antennae,

display, exposure, processing, and other factors, to

render a sharply-defined image. Resolution of a remote-

sensing system is of different types.

(1) Spectral Resolution

(2) Radiometric Resolution

(3) Spatial Resolution

(4) Temporal Resolution

Characteristics of RS systems: Resolution


Spectral Resolution

Incoming light

(mix of differentwavelengths)

Prism or Spectrometer

Detectors


Spectral Resolution / 2

coarse spectral resolution: only 1 value,same for soil and turbid water

finer spectral resolution: 3 values, each is different for soil / water


0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 2.10 3.10 4.20 6.20 8.20 10.20 12.20

SPOT Pan SPOT XS Landsat TM

NOAA AVHRR IRS LISS IRS WiFS

ADEOS AVNIR

Spectral resolution of some RS systems


Spectral Band Range (µm) used in Thematic Mapper (TM) onboard Landsat's 4 and 5 sensor system and their potential application

BandNumber

Band Range(µm)

Potential applications

1 0.45 to 0.52 coastal water mapping; soil/vegetation differentiation; deciduous/coniferous differentiation (sensitive to chlorophyll concentration); etc.

2 0.52 to 0.62 green reflectance by healthy vegetation; etc.

3 0.63 to 0.69 chlorophyll absorption for plant species differentiation;

4 0.78 to 0.90 bio-mass surveys; water body delineation;

5 1.55 to 1.75 vegetation moisture measurement; snow/cloud differentiation;

6 10.4 to 12.5 plant heat stress management; other thermal mapping; soil moisture discrimination;

7 2.08 to 2.35 hydrothermal mapping; discrimination of mineral and rock types;


Spectral Band Range (µm) used in Advance Very High Resolution Radiometer

(AVHRR) sensor onboard NOAA Satellite system and their potential application.

CHANNEL WAVE LENGTH) USESNUMBER (µm)

CHANNEL 1 0.58 - 0.68 cloud delineation, weather snow and ice mapping and monitoring, etc.

CHANNEL 2 0.73 - 1.1 surface water delineation, vegetation and agriculture assessment, range surveys, etc.

CHANNEL 3 3.53- 3.93 land/water distinction, sea surface temperature, hot spot detection (forest fires and volcanic activity),etc.

CHANNEL 4 10.3 - 11.3 day/night cloud mapping, sea and land surface temperature, soil moisture, volcanic eruption, etc.

CHANNEL 5 11.5 12.5 sea surface temperature measurement, soil moisture, weather, etc.


Multispectral images: Landsat TM

TM6 (10.4 -12.5)


Spatial resolution / 2

SPOT Pan (10m) Landsat TM (30m) IRS WiFS (188m) NOAA AVHRR (1.1km)

Landsat MSS (80m)SPOT XS (20m)

IRS Pan (6m)KVR (2m)


SATELLITESYSTEM

SOMEOPTICAL SENSORSYSTEM

LANDSAT 4/5

MSS

LANDSAT 4/5

TM

SPOT

XS

NOAA

AVHRR

MOS

MESSRJERS

OPSVINRandSWIR

ADEOS

AVNIR

IRS-1C

LISS-III

IRS-1C

WiFS

Spatial Resolution 80 m 30 m 20 m 1.1 km (LAC) 50 m 18 m X 24m

16 m 24 m 188 m (200m)

Off-nadir viewing(side-look)capability for the(PAN)Panchromaticmode for stereoimage dataacquisition)

SPOT PAN(10mresolution)0.51- 0.73 µm3 days revisitcapability

JERSOPSVINR(18m X24m)Bands 3 &40.76 - 0.86µm

ADEOSAVNIRPAN(8 mResolution)0.52 -0.72 µm

IRS-1C PAN(6 mresolution)(70 km swathwidth)0.50 - 0.70 µm(6-bit)

Spatial Resolution


Spatial resolution: TM and SPOT Pan


SATELLITE LANDSAT LANDSAT SPOT NOAA MOS JERS ADEOS IRS-1C IRS-1C

SYSTEM MSS TM XS AVHRR MESSR OPS AVNIR LISS-III WiFS

VINR

AND

SWIR

Revisit Cycle 16 16 20 (nadir) 1 image/day 17 44 41 (nadir) 24 (nadir)

(in days)

Temporal resolution

Sensor Satellite Level (bit) DescriptionsMSS LANDSAT 6 8 bits data after radiometric correctionTM LANDSAT 8HRV (XS) SPOT 8HRV (PA) SPOT 6AVHRR NOAA 10 both 10 and 16 bits’ data are available at distributionSAR JERS-1 3 real 3 bits, imaginary 3 bits

Quantization level of remote-sensing data


The remote sensing satellites are equipped with sensors looking down to the earth. They are the "eyes in the sky" constantly observing the earth as they move around the earth.

Remote Sensing Satellite

Remote Sensing Satellite

Remote Sensing satellite images gives a synoptic (bird’s eye) view of any places of the Earth surface, which helps to study, map, and monitor the Earth’s surface at local and/or regional/global scales. It is cost effective and gives better spatial coverage as compared to ground sampling.


There are several remote sensing satellite series in operation. Different satellite systems have different characteristics, e.g. resolutions, number of bands, and have their own importance for different application.

Satellite Systems Spatial Resolution Type Number of Bands Launched by

LANDSAT-ETM+LANDSAT-TMLANDSAT-MSSSPOT-XSSPOT-PANIRS-1C PANIRS-LISS-IIIIRS-WiFSCosmos -KVR1000IKONOSIKONOS ADEOS-AVNIR MNOAA AVHRRMOS MESSR

15,30,5030m80m20m10m6m24m188m2m1m4m16m1.1Km50m

Multi-spectralMulti-spectralMulti-spectralMulti-spectralPanchromaticPanchromaticMulti-spectralMulti-spectralPanchromaticPanchromaticMulti-spectralMulti-spectralMulti-spectralMulti-spectral

87431142114454

USAUSAUSAFrance, SwedenFrance, SwedenIndiaIndiaIndiaRussia/USACanadaCanadaJapanUSAJapan

Types of Remote Sensing Images


SATELLITE

SYSTEM

SOME

OPTICAL

SENSOR

SYSTEM

LANDSAT

4/5

MSS

LANDSAT4/5

TM

SPOT

XS

NOAA

AVHRR

MOS

MESSR

JERS

OPS

VINR

and

SWIR

ADEOS

AVNIR

IRS-1C

LISS-III

IRS-1C

WiFS

Spectral

Resolution

(Number of

Bands)

Four Seven Three Five Four Seven Four Four Two

Spectral ranges (wave-length portion of EMR) in µm (micrometers)

Blue 0.45 - 0.52 0.40 - 0.50

Green 0.50 - 0.60 0.53 - 0.61 0.50 - 0.59 0.51 - 0.59 0.52 - 0.60 0.52 - 0.62 0.52 - 0.59

Red 0.60 - 0.70 0.62 - 0.69 0.62 - 0.68 0.58 - 0.68 0.61 - 0.69 0.63 - 0.69 0.62 - 0.72 0.62 - 0.68 0.62 - 0.68

NIR 0.70 - 0.80 0.78 - 0.90 0.78 - 0.88 0.73 - 1.10 0.72 - 0.82 0.76 - 0.86 0.77 - 0.86 0.77 - 0.86

NIR 0.80 - 1.10 0.80 - 1.10 0.82 - 0.92

IIR 1.57 - 1.78 1.60 - 1.71 1.55 - 1.75

IIR 2.10 - 2.35 3.55 - 3.93 2.01 - 2.12

IIR (MIR) 2.13 - 2.15

IIR (MIR) 2.27 - 2.40

ThIR 10.45 - 11.66 10.3 - 11.2

FIR 11.5-12.5


Remote sensing images are normally in the form of digital images.Image processing techniques are applied to enhance the image to help visual interpretation, information extraction and to correct or restorethe image if the image has been subjected to geometric distortion, blurring or degradation by other factors. There are many image analysis techniques available and the methods used depending upon the requirements of the specific problem concerned.

Remote Sensing Images

Satellite Image of Kathmandu

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