imcorr软件使用方法.docx

imcorr软件使用方法.docx

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imcorr软件使用方法

IMCORRRelease1.1

$Date:

2000-03-0214:

12:

28-07$

倒不是试验参数，读数据成了最大的问题

（Note:

Thisfile,themakefiles,andacoupleofotherdetailsaboutthe

distributionhavebeenslightlyeditedandputunderrevisioncontrolbyBruce

Raup.Thesoftwareisfunctionallyunchanged（exceptforoneminor

compile-timeoption）,butthereleasenumberisnolonger1.0.Ifyouhave

commentsorsuggestionsforchangesoradditions,pleasesendthemtoB.

RaupandT.Scambos.）

NotesonusingIMCORRimage-to-imagegreylevelcorrelationsoftware

T.Scambos

（1）

M.Fahnestock

（2）

R.Bindschadler（3）

B.Raup（4）

（1）NationalSnowandIceDataCenterCIRESCampusBox449;154030thSt.

UniversityofColoradoBoulderCO80309-0449USA

vox:

303/492-1113fax:

303/492-2468net:

teds@icehouse.colorado.edu

（2）JointCenterforEarthSystemScience,DepartmentofMeterology,

UniversityofMaryland,CollegePark,MDUSA

voice:

301/405-5384net:

mark@firn.gsfc.nasa.gov

（3）Code971NASA/GoddardSpaceFlightCenterGreenbeltMD20771USA

Voice:

301/286-4717or301/286-2142Fax:

301/286-2717

Internet:

iceflow@laural.gsfc.nasa.gov（IP:

128.183.47.79）

（4）NationalSnowandIceDataCenter,CIRES;CampusBox449;154030thSt.

UniversityofColoradoBoulderCO80309-0449USA

Phone:

303-492-8814fax:

303-492-2468net:

braup@kryos.colorado.edu

INTRODUCTION

Thefollowingdocumentationisintendedtohelpinterestedusersacquire

andbeginusingIMCORR,asimpleimagecross-correlationprogramwhichcan

beusedtofindoffsetsoffeaturesinapairofimages.Thissoftware

usessubroutines【子程序，随源程序的原始码】foundwithinLAS5.0,anextensiveimageprocessing

packagewritteninFORTRANatNASA/Goddard.IMCORRconsistsofthese

subroutinesandasimpleCroutinethatactsasafrontend.Allthe

subroutinesrequiredfordisplacementanalysisarewithinthedirectory

associatedwiththisdocumentfile.

IMCORR

IMCORRtakestwoimagesandaseriesofinputparametersandattemptsto

matchsmallsubscenes（called'chips'【小窗口】）fromthetwoimages.Theprogram

usesafastfouriertransform【FFT快速傅里叶变换】-basedversionofanormalized

cross-covariance【正交互协方差】method（seeBerenstein,1983;alsoScambosetal.,1992）.

Themostcommonuseofthistypeofalgorithminimageprocessingisto

accuratelylocatetie-point【连接点，栓点】pairsintwoimagestocoregisterthem.

However,iftheimagesarealreadycoregisteredbyothermeans,the

algorithmmaybeusedtofindthedisplacementsofmovingfeatures,

providedthatthefeaturesshowlittlechangeintheirappearance,andthat

themotionisstrictlytranslational【平动，直线】.IMCORRtakesasinputtheimage

namesandsizes,parametersdeterminingsearchchipsize,referencechip

size,gridspacing,andoutputfilename.【全部参数】Further,presetoffsetsofsearch

chipcentersmaybespecified,andsubareasofthefullimagefilesmaybe

usedtorestricttheareaoverwhichIMCORRattemptstofinddisplacements.

AteachofthegridpointsIMCORRcalculatesacorrelationindexforevery

locationatwhichthereferencechipwillentirelyfitwithinthesearch

chip.IMCORRtakesthecorrelationvaluesinthevicinityofthebest

integer-pixel【整数像素】matchandinterpolatesapeakcorrelationlocationto

sub-pixelprecision.Theprogramreturnsafilecontainingthelocations

ofthegridcentersforthereferencechips,thedisplacementsrequiredto

bestmatchthechippairs（orindicatesthatnonecouldbefound）,and

severalqualitycontrolparametersthatmaybeusedtoevaluatethe

validityofthematch.Weusethisprogramtomeasureglaicervelocities;

however,thesameprogrammaybeusefulforotherapplications.

Itisimportantforthereadertounderstandthatallofthecorrelation,【相互关联】

peakfinding,anderrorestimationisdonebytheFORTRANsubroutinesfrom

LAS,whichwaswrittenbyothersatNASAlongbeforetheauthorsofthis

documentwereinvolvedinimageanalysis.WehavesimplyaddedtheCcode

whichmakestheuseoftheseroutinesmorestraightforwardandautomated

forvelocity-mappingapplications.

Apaperdescribingthedetailsofthistechniqueandthepreprocessingof

imagesrequiredtooptimizethedisplacementmeasurementsispublishedin

RemoteSensingofEnvironment（Scambosetal.,1992;seebibliography）.We

willgladlyprovideapreprintuponrequest.

GETTINGTHESOFTWARE

Thelatestdistributionforimcorrisat

http:

//www-nsidc.colorado.edu/NSIDC/ANTARCT_VELOC/imcorr.html.

LOADINGTHESOFTWARE

Transfertheentirecontentsofthe'distribution'directorytoyour

workstation（thetutorialdiscussionbelowwillassumeyouhavetransferred

thefourtestimageswehaveincludedinthedirectory）.Thisdirectoryis

roughly1.25Mbytes,andcontainsthefollowingfiles:

conv.y87testimagefile

conv.y89testimagefile

correlate.hHeaderfileforimcorr.c

cross.fFORTRANsource

esterr.fFORTRANsource

eval.fFORTRANsource

fang.y87testimagefile

fang.y89testimagefile%看样子有两组完整的实验数据

fft2d.fFORTRANsource

fitreg.fFORTRANsource

gcorr.fFORTRANsource

gnorm.fFORTRANsource

imcorr.cCsource

kvert.fFORTRANsource

makefile.LinuxmakefileforLinuxmachines%要用到的makefile

makefile.SGImakefileforSiliconGraphicsmachines

makefile.SUNmakefileforSunMicrosystemsmachines

README.txtthisfile

sums.fFORTRANsource

test1.outExampleoutputfile

test2.outExampleoutputfile

test3.outExampleoutputfile

TO_DO.txtlistofto-do's

COMPILE-TIMEOPTION

Beforecompiling,youcanuncomment（deletethe'#'character）thelinein

themakefilethatsays

#DEFS=-DCOMMANDLINE

Thiswillcauseimcorrtoprintthecommand-linethatwasissuedatthe

shellpromptasthefirstlineintheoutputfile,precededbya'#'

character.

【正式编译的时候，可以反注释（本来是注释的，删掉注释符号），但是如果不删掉也没关系吧?

只是在文件开头有所区别】

HOWTOCOMPILE

TheIMCORRsourcecodeisroughly65kilobytes.ItrequiresbothCandFORTRAN

compilers.Itcontainsnographicscommandsineitherlanguage,andshouldbe

relativelyeasytoporttoavarietyofsystems.WeuseSiliconGraphics

workstations;thesoftwarehasalsobeencompiledonSUNSparcstationsand

Linuxmachines.WehaveincludedmakefilefilesforSGI,Linux,andSUN

workstations.Togenerateanexecutablefilefromthesourcecode,type:

prompt>make-fmakefile.[SUNorSGIorLinux]imcorr，产生可执行文件

Onanysystem,toremovetheobjectfiles,type:

prompt>make-fmakefile.[SUNorSGIorLinux]clean

Ifyouwantorneedtomakeanychangestothemakefile,werecommend:

prompt>cpmakefile.[SUNorSGIorLinux]Makefile

prompt>viMakefile（makechangeswithwhatevereditoryoulike）

prompt>make

Bydefault,makeuses"Makefile"asinput,ifitexists.

Allofthesemakefilesproduceanexecutablefilenamedimcorr.

INPUTPARAMETERS

ThisIMCORRversiontakeseither5,10,or14inputparameters,【重载函数可默认设置】whichare

typedonthesamelineasthe'imcorr'commandseparatedbyspaces.Simply

typing'imcorr'andreturngivesalistoftherequiredinputparameters

foreachofthesethreeformats.

ListofInputParameters:

referenceimagefilename（generallytheolderimage）

searchimagefilename（generallythenewerimage）

numberofpixelsperlineinimages（nodefault）

numberoflinesinimages（nodefault）

outputfilename（doesnotneedtoexistpriortoarun）

searchchipsizeinpixels

（default:

64;mustbedivisibleby16,lessthanorequalto256;

entering'32'meansasearchchipof32x32pixels）

referencechipsizeinpixels

（default:

32;mustbedivisibleby16,lessthanorequalto128;

entering'32'meansarefchipof32x32pixels）

gridspacinginpixels

（default:

25;nolimitsexceptthoseimposedbytheimages;

gridsarealwayssquare;entering'25'meansthatthesearchand

referenceimagechipswillbecenteredonpoints25pixelsapart

inbothlineandsampledirections）

xoffsetofreferencechiprelativetosearchchipcenter（default:

0）

yoffsetofreferencechiprelativetosearchchipcenter（default:

0）

xoffsetofsubimagetobeanalysed（default:

0）

yoffsetofsubimagetobeanalysed（default:

0）

xextentofsubimage（default:

fullxextent）

yextentofsubimage（default:

fullyextent）

Thereferenceimagewillhavethesmaller,'referencechip',subimagesderived

fromit,atregulargridspacings,【网格间距】andthesechipswillbecomparedtolarger

'searchchip'subimagesderivedfromthesearchimage.Theimagesmustbethe

samesize,andasingle（sample,line）coordinatesystemwillbeusedforboth

ofthem.Inthefollowingdiscussion,itisassumedthattheimagesare

coregistered,i.e.,thatafeaturethatdoesnotmovewouldbefoundatthesame

（sample,line）coordinatesinbothimages.Regardingmaximumimagesize,

machinememoryisdynamicallyallocatedduringanIMCORRrun.Therefore,images

maybeverylarge;however,largerimageswillresultinslowerprocessingdue

tomemoryswapping.【内存交换】

Thexandyoffsetsofthesubimageanswerthequestion,"wheredoesthe

referencechipcomefrom?

".Forexample,iftheicehasmovedinthepositive

xdirection（totheright）by20pixels,thenthex-offsetshouldbe-20.

【offset说明了方向性】

Thecoordinatesystemhasxpositivetotheright,andypositivedownward:

-------------->x

|

|

|

|

|

|

V

y

Largesearchandreferencechipsizesslowtheruntimeconsiderably,anda

largereferencechipmaycauseproblemsifanydistortionofthefeatures

occursbetweenthetwoimages.Notethatifthesearchandreferencechipsare

derivedfromthesame（sample,line）gridcentersintheirrespectiveimages

（thedefaultcase）,themaximumdisplacementofafeaturethatcanbemeasured

is:

（searchchipsize/2-referencechipsize/2）*C2,andthismaximumapplies

onlytoexactlydiagonalmotion.

Gridspacingparameterdeterminesthedensity