Driver's HeadPoseMeasurement andCornerCenter Detection

Inthis paper, wedescribe development ofdriver's headposemeasurement andcornea center detection system. Similar researches havebeenperformed sofar. Mostresearches arebased onfeature point detection bythe template matching. Ingeneral, thetemplate matching hastheweakness tothechange intheexpansion andcontraction, rotation andbrightness. Toovercome these faults, three-dimensional shape alignment isintroduced. Three-dimensional shapealignment isperformed between driver's facemodelandshapedataobtained ineachtime.Then, three-dimensional shapes areanalyzed bystereovision. Moreover, shape alignment isperformed byICPregistration. ICPregistration canachieve highaccuracy alignment, butneeds hugecomputational effort, ingeneral. Tosolve this problem, this paper introduces areduction involume ofdata based onpattern information intheimage, coarse-to-fine search, andSIMDcomputing. Furthermore, this paper describes thecornea center estimation technique. Atfirst, this technique extracts theeyeregion imagefromresult oftheheadposemeasurement. Afterward, thecornea center is estimated byrecognition ofeyecontour andtheellipse fitting ofcornea. Itwasconfirmed byexperiments that the proposed technique canmeasure inhighaccuracy, andtheproposed technique isavailable inreal environment. To drivesafely, itiseffective tointroduce the environmental recognition systemsP'). Itis, however, not preferable to showthedriver allofinformation recognized bythese systems, because itisdifficult for thedriver toprocesstoomuchinformation. Thus, itis necessarytoeliminate theunnecessaryinformation that displayed bythedriving support system. Itisconsidered thattheoversight detection basedon driver's gaze estimation willbecomepowerfulcriterion for unnecessaryinformation. Thegaze position can be analyzed frombothdriver's headposeandgazevectors. Thispaper focuses on theheadpose measurement technique insixdegree offreedom. Moreover, the measurement ofthecorneacenter position isdescribed forgazeanalysis. Thenon-contact measurement technique ispreferable so asnottoinfluence thedriver. Inprevious works, itis proposed thenon-contact measurement technique using thecamera thatsettowardthedriver. Mitaetal(2) proposethemeasurement technique using single camera. Thistechnique measures theheadpose fromphysical relationship between thecenterofnose andtheeye's center ofgravity. However, themeasurement target is onlytheheadyaw angle, andotherangles cannotbe measured. Additionally, itisdifficult tomeasure head pose inhighaccuracyby single camera. Forthis problem, Matsumoto etall3) introduce thestereovision thatcan analyze inthree-dimension. Thistechnique measure theheadpose insixdegreeof freedom fromphysical relationship between eye cornersand angle ofmouththat aredetected bytemplate matching. Furthermore, template images formatching areobtained fromfull-face image. However, reliability oftemplate matching islowagainst expansion, contraction and rotation intheimagebythemovementofthehead. Then, we proposetomeasuretheheadposebyusing the three-dimensional shapealignment to dealthese problems. Thistechnique isbasedonICPregistration between anobtained shape dataandthe3Dface model madeinadvance. Secondly, themeasurement technique ofthecorneacenter position isexpressed. This technique isbased ontheactive contour modelandan ellipse fitting. Itwasconfirmed thattheproposed techniques couldmeasurein highaccuracy by experiment.