arcgis期末复习考点第十三章

Chapter13ReviewQuestions1.Howcanananalysismasksavetimeandeffortforrasterdataoperations?Becauseananalysismasklimitsdataanalysistocellsthatdonotcarrythecellvalueof“nodata,”itcansavetimeandeffortforrasterdataoperations.2.Whyisalocaloperationalsocalledacell-by-celloperation?Alocaloperationisalsocalledacell-by-celloperationbecauseitcomputesthecellvaluesintheoutputraster,onecellatatime.3.RefertoFigure13.3.Showtheoutputrasterifthelocaloperationusestheminimumstatistic.4.RefertoFigure13.4.Showtheoutputrasterifthelocaloperationusesthevarietystatistic.5.Figure13.5chastwocellswiththesamevalueof4.Why?Figure13.5chastwocellswiththesamevalueof4becausetheybothhavethecombinationof(1,2).6.Neighborhoodoperationsarealsocalledfocaloperations.Whatisthefocalcell?Thefocalcellisthecentercelloftheneighborhood.7.Describethecommontypesofneighborhoodsusedintheneighborhoodoperation.Commontypesofneighborhoodsincluderectangles,circles,annuluses,andwedges.Arectangleisdefinedbyitswidthandheightincells,withthefocalcellatthecenter.Acircleextendsfromthefocalcellwithaspecifiedradius.Anannulusordoughnut-shapedneighborhoodconsistsoftheringareabetweenasmallercircleandalargercirclecenteredatthefocalcell.Andawedgeconsistsofapieceofacirclecenteredatthefocalcell.8.RefertoFigure13.8.Showtheoutputrasteriftheneighborhoodoperationusesthevarietymeasure.9.RefertoFigure13.9.Showtheoutputrasteriftheneighborhoodoperationusestheminoritystatistic.10.Whatkindsofgeometricmeasurescanbederivedfromthezonaloperationsonasingleraster?Givenasingleinputraster,zonaloperationsmeasurethegeometryofeachzone,suchasitsarea,perimeter,thickness,andcentroid.11.Azonaloperationwithtworastersmustfirstdefineoneofthemasthezonalraster.Whatisazonalraster?Azonalrastercontainszones,whicharegroupsofcellsofsamevaluesorlikefeatures.Zonesmaybecontiguousornoncontiguous.12.RefertoFigure13.11.Showtheoutputrasterifthezonaloperationusestherangestatistic.13.Supposeyouareaskedtoproducearasterthatshowstheaverageprecipitationineachmajorwatershedinyourstate.Describetheprocedureyouwillfollowtocompletethetask.Step1:Downloadormaketheprecipitationgridandthewatershedgrid.Step2:Usetheprecipitationgridastheinputgridandthewatershedgridasthezonalgridandrunazonalmeanoperation.14.Explainthedifferencebetweenthephysicaldistanceandthecostdistance.Thephysicaldistancemeasuresthestraight-lineoreuclideandistance,whereasthecostdistancemeasuresthecostfortraversingthephysicaldistance.15.Whatisaphysicaldistancemeasureoperation?Aphysicaldistancemeasureoperationcalculatesstraight-linedistancesawayfromcellsdesignatedasthesourcecells.16.Agovernmentagencywillmostlikelyuseavector-basedbufferingoperation,ratherthanaraster-basedphysicaldistancemeasureoperation,todefineariparianzone.Why?Agovernmentagencywillnotusearaster-basedphysicaldistancemeasureoperationtodefineariparianzonebecausetheoperationisbasedoncells(e.g.,30-metercells),whichcannotclearlydelineateariparianzone.