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1、利用空间上下文寻找识别物体原作者：GeremyHeitz，DaphneKollerStanfordUniversityThingsvs.StuffStuff(n):Materialdefinedbyahomogeneousorrepetitivepatternoffine-scaleproperties,buthasnospecificordistinctivespatialextentorshape.Thing(n):Anobjectwithaspecificsizeandshape.From:Forsyth
2、etal.Findingpicturesofobjectsinlargecollectionsofimages.ObjectRepresentationinComputerVision,1996.FindingThingsContextiskey!OutlineWhatisContext?TheThingsandStuff(TAS)modelResultsSatelliteDetectionExampleD(W)=0.8D(W)=0.8ErrorAnalysisTypically…Weneedtolookout
3、sidetheboundingbox!FalsePositivesare OUTOFCONTEXTTruePositivesare INCONTEXTTypesofContextScene-Thing:Stuff-Stuff:gistcar“likely”keyboard“unlikely”Thing-Thing:[Torralbaetal.,LNCS2005][Gouldetal., IJCV2008][Rabinovichetal.,ICCV2007]TypesofContextStuff-Thing:Ba
4、sedonspatialrelationshipsIntuition:Trees=nocarsHouses=carsnearbyRoad=carshere“Carsdriveonroads”“Cowsgrazeongrass”“Boatssailonwater”Goal:UnsupervisedOutlineWhatisContext?TheThingsandStuff(TAS)modelResultsThingsDetection“candidates”Lowdetectorthreshold->“over-
5、detect”EachcandidatehasadetectorscoreThingsCandidatedetectionsImageWindowWi+ScoreBooleanR.V.TiTi=1:CandidateisapositivedetectionThingmodelTiImage WindowWiStuffCoherentimageregionsCoarse“superpixels”FeaturevectorFjinRnClusterlabelSjin{1…C}StuffmodelNaïveBayes
6、SjFjRelationshipsDescriptiveRelations“Near”,“Above”, “Infrontof”,etc.ChoosesetR={r1…rK}Rijk=1:DetectioniandregionjhaverelationkRelationshipmodelS72=TreesS4=HousesS10=RoadT1RijkTiSjR1,10,in=1TheTASModelRijkTiSjFjImage WindowWiWi:WindowTi:ObjectPresenceSj:Regi
7、onLabelFj:RegionFeaturesRijk:RelationshipNJKSupervised inTrainingSetAlways ObservedAlways HiddenUnrolledModelT1S1S2S3S4S5T2T3R2,1,above=0R3,1,left=1R1,3,near=0R3,3,in=1R1,1,left=1Candidate WindowsImage RegionsLearningtheParametersAssumeweknowRSjishiddenEvery
8、thingelseobservedExpectation-Maximization“Contextualclustering”ParametersarereadilyinterpretableRijkTiSjFjImage WindowWiNJKSupervised inTrainingSetAlways ObservedAlways HiddenLearnedSatelliteClu
