Robust wide baseline stereo from maximally stable extremal r(6)
时间:2025-04-03
时间:2025-04-03
The wide baseline stereo problem ,i.e.the problem of establishing correspondences between apair of images taken from different view points is studied.A new set of image elements that are put into correspondence,the so called extremal regions,is introduced.Extremal regions possess highly desirable properties
766
J.Matasetal./ImageandVisionComputing22(2004)761–767
Table3
Experimentalresults
TC
RoughRoughEGþcorrFineEGFined’MissEGd’
Bookshelf85250.48
151630.091Valbonne49270.17180820.080Wash171420.34220860.082Kampa303780.344221850.082Cyl.box63230.15102670.093Shout15144
0.43
220
86
0.08
1
Fordetails,seethetextatthebeginningofSection4.
Afterestablishingthe‘roughEG’theso-called‘guidedmatching’stepisapplied[2,5].Intheprocessof ndingtentativecorrespondences,atmostasinglecorrespondingregionisassociatedwithoneDR.Oftenthisassociationiserroneous,forinstanceifthereisarepetitivepatterninthescene.MoreoversomeDRsarenotmatchedatallsincetheyfailthe‘mutuallynearest’requirement.Giventhe‘roughEG’,evenratherimprecise,theprocessof ndingtentativematchescanberevisited.Theoriginaltentativecorrespon-dencesarediscardedandallpotentialmatchesconsistentwiththe‘roughEG’areselected.Thematchingnowneednotrelyonrotationalinvariants,sinceepipolarlinespassingthroughapairofmatchingregionsde netheirrelativeorientation[2].The‘guided’tentativecorrespondencesarethereforeselectedusingcorrelation.
Thecolumnheaded‘EGþcorr’givesthenumberofcorrespondencesconsistentwithroughEGthatpassedthecorrelationtest.Noticethatthenumbersaremuchhigherthanthoseinthe‘roughEG’column.The nalnumberofcorrespondencesisgiveninthepenultimatecolumn‘ neEG’.Averagedistancesfromepipolarlinesarepresentedincolumns‘roughd’’and‘ ned’’.Wecansee,thattheprecisionoftheestimatedEGisveryhigh,muchhigherthantheprecisionoftheroughEG.Thelastcolumnshowsthenumberofmismatches(foundmanually).
5.Conclusions
Anewmethodforwide-baselinematchingwasproposed.Thethreemainnoveltiesare:theintroductionofMSERs,robustmatchingoflocalfeaturesandtheuseofmultiplescaledmeasurementregions.
TheMSERsaresetsofimageelements,closedundertheaf netransformationofimagecoordinatesandinvarianttoaf netransformationofintensity.Anef cient(nearlinearcomplexity)andpracticallyfastdetectionalgorithmwaspresented.ThestabilityandhighutilityofMSERswasdemonstratedexperimentally.Anothernoveltyoftheapproachistheuseofarobustsimilaritymeasureforestablishingtentativecorrespondences.Duetotherobust-ness,wewereabletoconsiderinvariantsfrommultiple
measurementregions,evensomethatweresigni cantlylarger(andhenceprobablydiscriminative)thantheassociatedMSER.
GoodestimatesofEGwereobtainedonchallengingwide-baselineproblemswiththerobusti edmatchingalgorithmoperatingontheoutputproducedbytheMSERdetector.Theaveragedistancefromcorrespondingpointstotheepipolarlinewasbelow0.09oftheinter-pixeldistance.Signi cantchangeofscale(3.5£),illuminationconditions,out-of-planerotation,occlusion,locallyaniso-tropicscalechangeand3Dtranslationoftheviewpointareallpresentinthetestproblems.Testimagesincludedbothoutdoorandindoorscenes,somealreadyusedinpublishedwork.
Acknowledgements
TheauthorsweresupportedbytheEuropeanUnionprojectIST-2001-32184,bytheGrantAgencyoftheCzechRepublicprojectGACR102/02/1539andbytheAustrianMinistryofEducationprojectCONEXGZ45.535.TheSHOUTandWASHimageswerekindlymadeavailablebyTinneTuytelaars.
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