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1OpenSourcesoftwareandGISOverthepastdecade,GeographicalInformationSystems(GIS)haveevolvedfromahighlyspecializednichetoatechnologythataffectsnearlyeveryas-pectofourlives,fromfindingdrivingdirectionstomanagingnaturaldisas-ters.WhilejustafewyearsagotheuseofGISwasrestrictedtoagroupofresearchers,plannersandgovernmentworkers,nowalmosteverybodycancre-atecustomizedmapsoroverlayGISdata.Ontheotherhand,manycomplexproblemsrelatedtourbanandregionalplanning,environmentalprotection,orbusinessmanagement,requiresophisticatedtoolsandspecialexpertise.ThereforethecurrentGIStechnologyspansawiderangeofapplicationsfromviewingmapsandimagesonthewebtospatialanalysis,modelingandsimu-lations.GISisoftendescribedasintegrationofdata,hardware,andsoftwarede-signedformanagement,processing,analysisandvisualizationofgeoreferenceddata.Thesoftwarecomponenthasamajorimpactonthecapabilitiestoef-fectivelysolveawiderangeofproblemsusinggeospatialdata.ToensurethecontinuousinnovationandimprovementoftheGISsoftware,existenceofdi-verseapproachestoGISsoftwaredevelopmentiscrucial.Besidesthewidelyusedproprietarysystems,anOpenSourceGISplaysanimportantroleinadaptationofGIStechnologybystimulatingnewexperimentalapproachesandbyprovidingaccesstoGISfortheuserswhocannotordonotwanttouseproprietaryproducts.1.1OpenSourceconceptTheideaofOpenSourcesoftwarehasbeenaroundforalmostaslongassoftwarehasbeendeveloped.Theresultsofresearchanddevelopmentattheuniversitiesandgovernmentlaboratorieshavebeenoftenmadeavailableinthe21OpenSourcesoftwareandGISformofPublicDomainsoftwarepackages.RichardM.StallmanfirstdefinedtheconceptofFreeSoftwareinformoffourfreedoms:0.freedom:Thefreedomtoruntheprogram,foranypurpose.1.freedom:Thefreedomtostudyhowtheprogramworks,andadaptittoyourneeds.2.freedom:Thefreedomtoredistributecopies.3.freedom:Thefreedomtoimprovetheprogram,andreleaseyourimprove-mentstothepublic,sothatthewholecommunitybenefits.Softwarefollowingthesefourprinciplesiscalled“FreeSoftware”.In1984,RichardM.StallmanstartedtoworkontheGNU-Projectandin1985hecreatedthe“FreeSoftwareFoundation”tosupporttheFreeSoftwareconcept.ThelicenseoftheGNU-Project,theGNUGeneralPublicLicensenotonlygrantsthefourfreedomsdescribedabove,butitalsoprotectsthem.Theuserofthesoftwareisalsoprotectedsincethesefreedomsareguaranteed.Becauseofthisprotection,theGPLhasbeenthemostwidelyusedlicenseforFreeSoftware.Thebasicideabehindfreesoftwareisbasedontheassumptionthatbyallowingtheprogrammerstoread,redistribute,andmodifythesourcecode,thesoftwareevolves:itgetsimproved,bugsarefixedandcapabilitiesexpanded.Theubiquitousavailabilityofthesourcecodeandthecontinuous,ofteninstantaneouspeer-reviewofthecodecontributesignificantlytothisprocess.YoucanlearnmoreabouttheideasbehindtheOpenSourceattheOpenSource1andFreeSoftware2Websites.FullaccesstothesourcecodeisparticularlyimportantforGISbecausetheunderlyingalgorithmscanbecomplexandcangreatlyinfluencetheresultsofspatialanalysisandmodeling.Tofullyunderstandsystem’sfunctionality,whichisnotasobviousasitmaybe,forexample,forawordprocessingsoftware,itisimportanttobeabletoreviewandverifytheimplementationofaparticularfunction.Whileanaverageusermaynotbeabletotracebugswithinacomplexsourcecode,thereisanumberofspecialistswillingtotest,analyzeandfixthecode.Thedifferentbackgroundsandexpertiseofthesedevelopersanduserscontributetothesynergethiceffectsleadingtofasterandmorecosteffectivesoftwaredevelopmentofastableandrobustproduct.TheOpenSourceGeospatialFoundationOverthepastfewyearsagrowingnumberofOpenSourceGIS,Webmapping,andGPSprojectshasbeenestablishedwithdifferentgoals.Mostofthemarelistedatthe“FreeGISportal”Website3.Smallerprojectsareusuallybasedonindividualdeveloper’sinitiative,whenthelackofavailablesoftwareforaspecificapplicationissolvedbyhisowndevelopmentandtheresultisthenmadeavailabletothepublicon1OpenSourceWebSite,://://finishedquickly,othersevolveovertime.Ingeneral,theOpenSourcedevelopmentisverydynamic.TheOpenSourcelicensesandthefreeaccessthroughtheInternetenablethenewcontributorstakeoveranabandonedprojectandcontinuethedevelopment.Theoverallideadif-ferssignificantlyfromthestrategiesusedintheproprietaryGISdevelopmentindustries.InFebruary2006,theOpenSourceGeospatialFoundation(OSGeo4)hasbeencreatedtosupportandpromoteworldwideuseandcollaborativedevel-opmentofOpenSourcegeospatialtechnologiesanddata.ItincludesGRASSasoneofitsfoundingprojects.MatureopensourcegeospatialsoftwarethatundergoesrigorousreviewofitscodeanddevelopmentstructurebecomesanofficialOSGeoproject.Webmappingsystems,desktopapplications,geospa-tiallibrariesandametadatacatalogarerepresented.ThefoundationsupportsoutreachandadvocacyactivitiesthatpromoteOpenSourceconceptsandprovidesfinancial,organizationalandlegalhelptothebroaderOpenSourcegeospatialcommunity.Italsobuilds