Landsat TutorialWord格式.docx

Landsat TutorialWord格式.docx

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ReturnBeamVidiconsandMulti-SpectralScannerSystemswereflownonthefirstthreeLandsats. 

TheMSSprovedtobeamoreusefulandreliableinstrumentthattheRBV. 

Landsats-4and-5wereequippedwithanMSSandanimprovedversionoftheMSS,theThematicMapper（TM）. 

Landsat-6carriedan"

EnhancedThematicMapper"

（ETM）only,andLandsat-7iscarryingan"

EnhancedThematicMapper-plus,"

orETM+. 

TheoperatingdatesoftheLandsatsatellitesandtheinstrumentsonthemarelistedonTable1.

Launched

Retired

Instruments

Landsat-1（ERTS-1）

July23,1972

January,1978

RBV,MSS

Landsat-2

January22,1975

July,1983

Landsat-3

March5,1978

September,1983

Landsat-4

July16,1982

June,2001*

MSS,TM

Landsat-5

March1,1984

Landsat-6

October5,1993

ETM

Landsat-7

April15,1999

ETM+

Table1.LandsatSatellites,theirOperationalPeriods,andTheirInstruments.

*TheLandsat-4sensorswerenotoperationalafterJuly,1987;

thesatellitewaslaterusedformaneuvertesting.

ThedataontheseCD-ROMs,calledtheGeoCoverdataset,covertheUnitedStatesofAmerica,includingAlaskaandHawaii. 

ThedatasetwasproducedbytheEarthSatelliteCorporationforNASAandcontainsapproximately900TMimages,orscenes. 

EachLandsatsceneisabout115mileslongand115mileswide（or100nauticalmileslongand100nauticalmileswide,or185kilometerslongand185kilometerswide）. 

ThisdatasetcoverstheUnitedStatesaround1990andcamefromobservationsacquiredbytheLandsat-5satellite. 

Becauseofsatelliteschedulingconstraintsandcloudcoverobscuringtheground,thescenesintheGeoCoverdatasetwerenotallobserved（acquired）onthesamedayorwithinthesamemonth,butincludescenesacquiredwithinayearortwoof1990. 

Withineachimageorpicture,thesmallestpictureelement,orpixel,coversasquare28.5metersonaside. 

Nomatterhowmuchyouzoominonanimage,thesmallestsquarethatyoucanseewillbe28.5metersonaside-evenifthereareonlyafewbigsquaresonyourscreen. 

Thatdatasquareisabout94feetonaside,oranareaofaboutonefifthofanacreorabout0.08hectare. 

TheTMpixelsizeenablesobservationoflargenaturalfeatures,suchasvolcanos,rivers,andforests,andlargeman-madefeatures. 

Majorhighways,officebuildings（suchasthePentagonorUSCapitolbuilding）,cityparksandagriculturalfields,airports,majorbridgesanddamsareapparent,butnarrowstreets,creeksandstreams,individualhouses,andautomobilescannotbediscerned.

Sincethedataarespreadover4CD-ROMs,theUnitedStateswasbrokenupintosmallerareascalledtilesormosaics. 

CollectionsoftileswereputoneachCD-oneCD-ROMcoverstheeasternUnitedStates,anothercoversthecentralUnitedStates,athirdCD-ROMcoversthewesternUnitedStates,andonefinalCD-ROMcoversAlaskaandHawaii. 

Eachtilecoversanareaof6degreesoflongitude（12degreesoflongitudeatlatitudesabovethan60degrees,affectingonlyAlaskandata）by5degreesoflatitude. 

AdescriptionofthetilingschemecanbefoundintheGeoCoverProductDescriptionSheet（GeoCover.doc;

alsoAppendix3.）. 

Technicallyspeaking,thesedatawereorthorectified（geometricallycorrectedsothattheywouldappearastheywouldonamap,alwayslookingstraightdownandnotfromofftoaside）. 

Thenthedatawereprojected（displayed）usingtheUniversalTransverseMercatorprojectiontominimizethedistortioncausedbytakingapieceofasphereandflatteningit.

TheTMinstrumentonLandsat-5andtheETM+instrumentonLandsat-7observetheEarthwith7differentfiltersor"

bands"

. 

Bands1,2,3,4,5,and7onbothinstrumentsaresensitivetolightenergyfromthesunreflectedbythesurfaceoftheEarth. 

Eachbandissensitivetoadifferentpartofthereflectedsolarenergy. 

Thepartsofthereflectedenergyaredefinedbythelengthofthelightwaves. 

Thus,band1oftheTMandETM+instrumentsrecordsreflectedlightenergyonlyintherangeof0.45microns（µ

m-amicronisonemillionthofameterlong）to0.52µ

m. 

Thehumaneyeseesreflectedlightinthatbandofwavelengthsasthecolorblue;

hence,band1issometimesreferredtoastheblueband. 

Inasimilarmanner,bands2and3oftheTMandETM+instrumentsrecordreflectedgreenandredlight,respectively.

TMandETM+bands4,5,and7recordreflectedlightinwavelengthsthathumaneyescannotdetect. 

Thesebandsarereferredtoasnearinfrared（NIR,band4）andshortwaveinfrared（SWIR,bands5and7）.

Band6oftheTMandETM+instrumentsisdifferentfromalltheotherbandsbecauseitdoesnotrecordreflectedlightenergy,butratherheatenergyemittedbytheEarth'

Inadditiontothesebands,theETM+instrumentalsohasaneighthband,calledthepanchromaticsharpeningband. 

ETM+band8issensitivetoreflectedlightenergyacrossabroadrangeofwavelengthsthatincludesblue,green,redandnearinfrared. 

Thispanchromaticbandhasaspatialresolutionof15meters,ratherthanthe28.5or30metersofbands1,2,3,4,5and7. 

ThesensitivitiesofMSS,TMandETM+bandsarelistedinTable2.

Band

RBV

MSS

TM

1

.48-.57µ

mgreen

.45-.52µ

mblue

2

.58-.68µ

mred

.52-.6µ

.53-.61µ

3

.69-.83µ

mIR

.63-.69µ

4

.5-.6µ

.76-.9µ

mNIR

.75-.9µ

5

.6-.7µ

1.55-1.75µ

mSWIR

6

0.7-0.8µ

10.4-12.5µ

mTIR

7

0.8-1.1µ

2.08-2.35µ

2.1-2.35µ

8

.52-.9µ

mpanchromatic

Table2. 

LandsatInstrumentBands.IR=infrared;

NIR=nearinfrared;

SWIR=short

wavelengthinfrared;

TIR=thermalinfrared（longwavelength）;

andµ

m=micronormicrometer.

Whatdothedifferentbandsmeantouswhenwelookatthedata?

Tofindoutwhateachindividualbandseesbest,orbetterthantheothers,checktheLandsat-7imagesshowninAppendix2. 

Theindividualbandimagesappearasgrayscaleimages-likeold-fashionedblack-and-whitephotographs. 

However,theycanbecombinedtoformcompositeimages,withadifferentgrayscaleimagefeedingadifferentcolorgun（typicallyared-green-blue,orRGBcombination）. 

Therearemanyband-colorcombinationsthattellusefulstories. 

Threedifferentandoftenusedcompositesaresummarizedbelow.

______________________________________________________________________________

TrueColor:

Forthetruecolorrendition,band1isdisplayedinthebluecolor,band2isdisplayedinthegreencolor,andband3isdisplayedintheredcolor. 

Theresultingimageisfairlyclosetorealistic-asthoughyoutookthepicturewithyourcameraandwereridinginthesatellite. 

Butitisalsoprettydull-thereislittlecontrastandfeaturesintheimagearehardtodistinguish.

False-Color,alsocalledNearInfraredorNIR:

Inthisimage,band2isdisplayedinblue,band3isdisplayedingreen,andband4isdisplayedinred. 

Thisrenditionlooksratherstrange-vegetationjumpsoutasabrightredbecausegreenvegetationreadilyreflectsinfraredlightenergy!

Itissimilartopicturestakenfromaircraftwhenusinginfraredfilmandisveryusefulforstudyingvegetation.

___________________________________________________________________________

Short-WavelengthInfrared,orSWIR:

InthisSWIRimage,band2isdisplayedinblue,band4isdisplayedingreen,andband7（or5）isdisplayedinred. 

Thisrenditionlookslikeajazzeduptruecolorrendition-onewithmorestrikingcolors.

ThisisthebandcombinationwasusedintheGeoCoverdataset. 

ItisbuiltintotheGeoCoverdataandcannotbechanged. 

Further,thecontrastandbrightnesshavebeenalteredintheGeoCoverdatasettomakeamoreconsistentoverallmosaic.

TheappearanceofdifferentsurfacefeaturesforthedifferentcompositeimagesissummarizedonTable4.

TrueColor

Red:

Band3 

Green:

Band2

Blue:

Band1

FalseColor

Band4

SWIR（GeoCover）

Band7

Treesandbushes

OliveGreen

Red

Shadesofgreen

Crops

Mediumtolig