FRAGSTATS翻译.docx

FRAGSTATS翻译.docx

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FRAGSTATS翻译

FRAGSTATSacceptsrasterimagesinavarietyofformats,includingArcGrid,ASCII,BINARY,ERDAS,andIDRISIimagefiles.FRAGSTATSdoesnotacceptArc/Infovectorcoveragesliketheearlierversion2.Allinputdataformatshavethefollowingcommonrequirements:

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Allinputgridsshouldbesignedintegergrids,ideallycontainingallnon-zeroclassvalues（i.e.,eachcellshouldbeassignedanintegervaluecorrespondingtoitsclassmembershiporpatchtype）.Note,FRAGSTATSassumesthatthegridsare‘signed’integergrids;inputtingan‘unsigned’integergridmaycauseproblems.Inaddition,notethatassigningthezerovaluetoaclassisallowable,butFRAGSTATSwillreclassifyallzerocellvaluestoanewclassvalueequalto1plusthelargestclassvalueintheinputlandscape.Thisprocedureisnecessarybecauseazerobackgroundclassvaluemaycauseproblemsinthemovingwindowanalysisbecauseabackgroundvalueofzerointheoutputgridcannotbedistinguishedfromacomputedmetricvalueofzero.Inaddition,azeroclassvaluemaycauseproblemswhenthelandscapecontainsaborderbecausezerocannotbenegative,yetallcellsinthebordermustbenegativeintegers）.Thus,allzerocellsareassumedtobeinterior（i.e.,insidethelandscapeofinterest）.Forthesereasons,itissimplertoavoidtheuseofzeroclassvaluesaltogether.

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Allinputgridsshouldconsistofsquarecellswithcellsizespecifiedinmeters.Forcertaininputformats（ASCIIandBINARY）,thisisnotanissuebecausecellsareassumedtobesquareandyouarerequiredtoenterthecellsize（inmeters）inthegraphicaluserinterface.However,FRAGSTATSassumesthatallotherimageformats（ArcGrid,ERDAS,andIDRISI）includeheaderinformationthatdefinescellsize.Consequentlytheseimagesmusthaveametricprojection（e.g.,UTM）toensurethatcellsizeisgiveninmetricunits.

Therearesomeadditionalspecialconsiderationsforeachinputdataformat,asfollows:

（1）ArcGridcreatedwithArc/Info.Note,touseArcGridsyoumusthaveArcViewSpatialAnalystorArcGISinstalledonyourcomputerandFRAGSTATSmusthaveaccesstoacertain.dllfilefoundeitherintheArcViewBin32directory（forArcViewSpatialAnalystusers）ortheArcGISBindirectory（forArcGISusers）.Specifically,apathtothecorrespondingdlllibraryfileshouldbespecifiedintheenvironmentalsettingsunderNTorWindows2000operatingsystems,orapathstatementincludedintheautoexec.batfile,e.g.,underWindows98,asfollows:

WindowsNT:

YoucanaddthenecessaryPathvariableoredittheexistingoneviatheControlpanel-SystemProperties-Environmenttab.AddanewvariableoredittheexistingPathvariableinthesystemvariables,nottheuservariables（thiswillrequireadministrativeprivileges）.Addthefullpathtotheappropriate.dllfile.IfyouareusingArcViewSpatialAnalyst,therequiredfileistheavgridio.dllfileanditistypicallyinstalledinthefollowingpath:

\esri\av_gis30\arcview\bin32.IfyouareusingArcGIS,therequiredfileistheaigridio.dllfileanditistypicallyinstalledinthefollowingpath:

\esri\arcinfo\arcexe81\bin.Note,yoursoftwareversionnumberandpathmaybedifferentsobesuretolocatethe.dllfileonyourcomputerandenterthecorrectpath.IfyouareusingbothSpatialAnalystandArcGIS,thenyoucanentereitherorbothpathstothePathsystemvariable.

Windows2000/XP:

YoucanaddthenecessaryPathvariableoredittheexistingoneviatheControlpanel-SystemProperties-Advancedtab-EnvironmentVariablesbutton.AddanewvariableoredittheexistingPathvariableinthesystemvariables,nottheuservariables（thiswillrequireadministrativeprivileges）.Then,followingtheinstructionsabovefor.

Windows95/98:

YoumustaddthenecessaryPathstatementtotheautoexec.batfile.First,searchyourcomputerfortheautoexec.batfileandopenitusinganytexteditor.Then,eitheraddaPathstatementoredittheexistingone.Addthefullpathtotheappropriate.dllfile.IfyouareusingArcViewSpatialAnalyst,therequiredfileistheavgridio.dllfileanditistypicallyinstalledinthefollowingpath:

\esri\av_gis30\arcview\bin32.IfyouareusingArcGIS,therequiredfileistheaigridio.dllfileanditistypicallyinstalledinthefollowingpath:

\esri\arcinfo\arcexe81\bin.Thus,thepathstatementshouldlooksomethinglike:

PATHc:

\esri\av_gis30\arcview\bin32.Note,yoursoftwareversionnumberandpathmaybedifferentsobesuretolocatethe.dllfileonyourcomputerandenterthecorrectpath.IfyouareusingbothSpatialAnalystandArcGIS,thenyoucanentereitherorbothpathstothePathsystemvariable.Ifyouareaddingthepathtoanexistingpath,simpleuseasemicolontoseparatetheuniquepathsinthePathstatement.Aftersavingthefileyouwillneedtorebootyourmachineforthechangetotakeeffect.

（2）r.Eachrecordshouldcontain1imagerow.Cellvaluesshouldbeseparatedbyacommaoraspace（s）.Note,itwillbenecessarytostrip（delete）theheaderinformationfromtheimagefileifitexists,butbesuretokeepitforlaterreferenceregardingbackgroundcellvalue,#rows,and#columns.

（3）32-bitbinaryfile,noheader;nootherlimitations.

（4）16-bitbinaryfile,noheader.PatchIDoutputfile,ifselected,willbeoutputinsigned32-bitintegerformattoaccommodateagreaternumberofpatches.Inaddition,becausemovingwindowanalysisrequiresfloatingpoints,ifmovingwindowanalysisisselected,theoutputgridsproducedwillbe32-bitfloatingpointgrids.

（5）8-bitbinaryfile,noheader.PatchIDoutputfile,ifselected,willbeoutputinsigned32-bitintegerformattoaccommodateagreaternumberofpatches.Inaddition,becausemovingwindowanalysisrequiresfloatingpoints,ifmovingwindowanalysisisselected,theoutputgridsproducedwillbe32-bitfloatingpointgrids.

（5）ERDASimagefiles（.gis,.lan,and.img）.FRAGSTATSacceptsimagesfrombothERDAS7（.gisand.lan）andERDAS8（.gis,.lan,and.img）,butthelimitationsaresomewhatdifferent,asfollows:

ERDAS8Files.–FRAGSTATSaccepts.gis,.lan,and.imgfilesusedbycurrentversionsofERDASIMAGINE,includingsigned8-,16-,and32-bitintegergrids.While.gisand.lanfileformatsaresupported,theirlimitationsmakethemlesspracticalthan.img（seediscussionofERDAS7filesbelow）.CareshouldbetakenwhenpreparingthedatatobeusedwithFRAGSTATS,especiallywhenimportingdatafromotherformats（forinstancefromArcGrid）.Besuretosettheimportoptionsto‘signedinteger’.Regardlessoftheinputintegerformat（8-,16-,or32-bit）,thepatchIDoutputfilecreatedbyFRAGSTATSwillbeasigned32-bitinteger,andifmovingwindowanalysisisselected,alloutputgridswillbe32-bitfloatingpoint.Multi-layeredfilesarenotrejected,butonlylayeroneisprocessedandtheoutputsareallsinglelayered.Asnotedabove,cellsmustbesquare,notrectangular,andthemeasurementunitshouldbemeters.Ifthemeasurementunitisnotspecified,thenitisassumedtobemeters.ThecellsizeandmeasurementunitspecificationcanbechangedwithinERDASImagineusingtheImageInfotool->ChangeMapModelfromtheEditmenu.Theprojectioninformationexistingintheinputfileispassedunchangedtotheoutputfiles.FRAGSTATSdoesnotusethisinformationinternally.

ERDAS7files.--FRAGSTATSaccepts.gisand.lanfilesusedbyERDAS7,whicharelimitedtounsigned8-or16-bitintegergrids.FRAGSTATSwillacceptboth8-bitand16-bitintegerfilesanditwillrejectmulti-layeredfiles.While.gisand.lanfileformatsaresupported,theirlimitationsmakethemlesspracticalthan.img.Inparticular,ERDAS7.xfilesarelimitedtounsignedintegers（i.e.,onlypositiveintegers）,thereforelandscapeborders（whichrequirenegativeclassvalues）cannotberepresented.AnotherconsequenceofthisparticularlimitationisthatFRAGSTATS-generatedpatchIDfileswillnotfillthenon-landscapecells（i.e.,nodatacells）withtheusualvalue（minusthebackgroundclassvalue）,butwithzerovalues.Therestrictionto8-or16-bitintegersimposessomelimitationswhenusingtheFRAGSTATSonlargegrids.Specifically,unsigned16-bitintegerscanonlytakeonvaluesupto65,534.Thus,classIDvaluesarelimitedtointegerswithinthisrange（note,thisshouldnotbeaproblem,sinceitisunlikelythatanyonewouldhavemorethan65,534patchtypes）.Similarly,patchIDvaluesinthepatchIDoutputgridoptionallyproducedbyFRAGSTATSarelimitedtothesamerange,effectivelylimitingthenumberofpatchesinthisoutputgridto65,534.Ifthegridcontainsmorethanthisnumberofpatches,FRAGSTATSwillnotbeabletooutputauniqueIDforeachpatchandtheuserwillhavetosomehowdistinguishamongpatcheswiththesameID.Finally,becausethemovingwindowanalysisrequires32-bitoutputfiles（inordertooutputfloatingpointvalues）,movingwindowanalysisisnotsupportedwithERDAS7files.

（6）IDRISIimagefiles（.rdc）.IDRISIcurrentlysupportssigned8-or16-bitintegersand32-bitfloatingpointgrids.ThisimposessomelimitationswhenusingtheFRAGSTATSonlargegrids.Specifically,signed16-bitintegerscanonlytakeonvaluesbetween-32,768and32,767.Thus,classIDvaluesarelimitedtointegerswithinthisrange（note,thisshouldnotbeaproblem,sinceitisunlikelythatanyonewouldhavemorethan32,767patchtypes）.Similarly,patchIDvaluesinthepatchIDoutputgridoptionallyproducedbyFRAGSTATSarelimitedtothesamerange,effectivelylimitingthenumberofpatchesinthisoutputgridto37,767.Ifthegridcontainsmorethanthisnumberofpatches,FRAGSTATSwillnot