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為wei了le提ti高gao計ji算suan精jing度du。通tong過guo十shi多duo年nian的de不bu懈xie努nu力li,理li論lun上shang的de問wen題ti已yi基ji本ben解jie決jue,目mu前qian研yan究jiu的de重zhong點dian是shi如ru何he提ti高gao標biao定ding算suan法fa的de魯lu棒bang性xing以yi及ji如ru何he很hen好hao地di用yong這zhe些xie理li論lun來lai解jie決jue實shi際ji視shi覺jiao問wen題ti。為wei了le提ti高gao魯lu棒bang性xing,建jian議yi更geng多duo的de使shi用yong分fen層ceng逐zhu步bu自zi標biao定ding方fang法fa,並bing應ying對dui自zi標biao定ding的de結jie果guo進jin行xing線xian性xing優you化hua。還hai需xu確que定ding非fei線xian性xing畸ji變bian校xiao正zheng參can數shu。而er新xin的de比bi較jiao符fu合he攝she像xiang機ji成cheng像xiang物wu理li模mo型xing且qie又you便bian於yu分fen析xi計ji算suan的de實shi用yong模mo型xing是shi條tiao另ling辟pi蹊qi徑jing的de發fa展zhan方fang向xiang。攝she像xiang機ji自zi標biao定ding相xiang對dui於yu激ji進jin方fang法fa有you更geng好hao的de靈ling活huo性xing和he實shi用yong性xing,本ben文wen對dui基ji於yu機ji器qi視shi覺jiao的de攝she像xiang機ji標biao定ding理li論lun與yu各ge種zhong方fang法fa進jin行xing了le研yan究jiu。保bao守shou的de攝she像xiang機ji標biao定ding需xu要yao標biao定ding參can照zhao物wu。

以yi由you此ci重zhong建jian和he識shi別bie物wu體ti。而er空kong間jian物wu體ti外wai表biao某mou點dian的de三san維wei幾ji何he位wei置zhi與yu其qi在zai圖tu像xiang中zhong對dui應ying點dian之zhi間jian的de相xiang互hu關guan係xi是shi由you攝she像xiang機ji成cheng像xiang的de幾ji何he模mo型xing決jue定ding的de這zhe些xie幾ji何he模mo型xing參can數shu就jiu是shi攝she像xiang機ji參can數shu。大da多duo數shu條tiao件jian下xia,機ji器qi視shi覺jiao的de基ji本ben任ren務wu之zhi一yi是shi從cong攝she像xiang機ji獲huo取qu圖tu像xiang信xin息xi並bing計ji算suan三san維wei空kong間jian中zhong物wu體ti的de幾ji何he信xin息xi。這zhe些xie參can數shu必bi需xu通tong過guo實shi驗yan與yu計ji算suan才cai幹gan得de到dao這zhe個ge過guo程cheng被bei稱cheng為wei攝she像xiang機ji定ding標biao(或稱為標定)標定過程就是確定攝像機的幾何和光學參數,以及攝像機相對於世界坐標係的方位。由於標定精度的大小,直接影響著計算機視覺(機器視覺)精度。因此,隻有做好了攝像機標定工作,後續工作才幹正常展開,可以說,提高標定精度也是當前科研工作的重要方麵。
1攝像機透視投影模型
這個投影可用成像變換(即攝像機成像模型)laimiaoshu。shexiangjichengxiangmoxingfenweixianxingmoxinghefeixianxingmoxing。zhenkongchengxiangmoxingjiushuyuxianxingshexiangjimoxing,shexiangjitongguochengxiangtoujingjiangsanweichangjingtouyingdaoshexiangjierweixiangpingmianshang。benwenjiutaolunzaizhezhongmoxingxia,moukongjiandianyuqituxiangtouyingdianzaigezhongzuobiaoxixiadebianhuanguanxi。
2標定分類
攝she像xiang機ji標biao定ding可ke以yi分fen為wei保bao守shou的de攝she像xiang機ji標biao定ding方fang法fa和he攝she像xiang機ji自zi標biao定ding方fang法fa兩liang大da類lei。激ji進jin攝she像xiang機ji標biao定ding的de基ji本ben方fang法fa是shi一yi定ding的de攝she像xiang機ji模mo型xing下xia,總zong的de來lai說shuo。通tong過guo對dui特te定ding標biao定ding參can照zhao物wu進jin行xing圖tu像xiang處chu置zhi,並bing利li用yong一yi係xi列lie數shu學xue變bian換huan公gong式shi計ji算suan及ji優you化hua,來lai求qiu取qu攝she像xiang機ji模mo型xing內nei部bu參can數shu和he外wai部bu參can數shu。然ran而er,該gai方fang法fa在zai場chang景jing未wei知zhi和he攝she像xiang機ji任ren意yi運yun動dong的de一yi般ban情qing況kuang下xia,其qi標biao定ding很hen難nan實shi現xian。20世紀90年代初,FaugeraLuongMaybank等deng人ren首shou次ci提ti出chu了le攝she像xiang機ji自zi標biao定ding方fang法fa。這zhe種zhong自zi標biao定ding法fa利li用yong攝she像xiang機ji自zi身shen參can數shu之zhi間jian的de約yue束shu關guan係xi來lai標biao定ding,而er與yu場chang景jing和he攝she像xiang機ji的de運yun動dong無wu關guan,所suo以yi更geng為wei靈ling活huo。
3激進攝像機標定方法
如基於3D立體靶標的攝像機標定、基於2D平麵靶標的攝像機標定、以及基於徑向約束的攝像機標定等。保守的攝像機標定方法依照標定參照物與算法思路可以分成若幹類。
3.1基於3D立體靶標的攝像機標定
靶ba標biao上shang每mei一yi個ge小xiao方fang塊kuai的de頂ding點dian均jun可ke作zuo為wei特te征zheng點dian。每mei個ge特te征zheng點dian相xiang對dui於yu世shi界jie坐zuo標biao係xi的de位wei置zhi在zai製zhi作zuo時shi應ying精jing確que測ce定ding。攝she像xiang機ji獲huo得de靶ba標biao上shang特te征zheng點dian的de圖tu像xiang後hou,基ji於yu3D立體靶標進行攝像機標定是將一個3D立(li)體(ti)靶(ba)標(biao)放(fang)置(zhi)在(zai)攝(she)像(xiang)機(ji)前(qian)。由(you)於(yu)表(biao)示(shi)三(san)維(wei)空(kong)間(jian)坐(zuo)標(biao)係(xi)與(yu)二(er)維(wei)圖(tu)像(xiang)坐(zuo)標(biao)係(xi)關(guan)係(xi)的(de)方(fang)程(cheng)是(shi)攝(she)像(xiang)機(ji)內(nei)部(bu)參(can)數(shu)和(he)外(wai)部(bu)參(can)數(shu)的(de)非(fei)線(xian)性(xing)方(fang)程(cheng),如(ru)果(guo)忽(hu)略(lve)攝(she)像(xiang)機(ji)鏡(jing)頭(tou)的(de)非(fei)線(xian)性(xing)畸(ji)變(bian)並(bing)把(ba)透(tou)視(shi)變(bian)換(huan)矩(ju)陣(zhen)中(zhong)的(de)元(yuan)素(su)作(zuo)為(wei)未(wei)知(zhi)數(shu),來(lai)給(gei)定(ding)一(yi)組(zu)三(san)維(wei)控(kong)製(zhi)點(dian)和(he)對(dui)應(ying)的(de)圖(tu)像(xiang)點(dian),那(na)麼(me),就(jiu)可(ke)以(yi)利(li)用(yong)直(zhi)接(jie)線(xian)性(xing)變(bian)換(huan)法(fa)來(lai)求(qiu)解(jie)透(tou)視(shi)變(bian)換(huan)矩(ju)陣(zhen)中(zhong)的(de)各(ge)個(ge)元(yuan)素(su)。所(suo)以(yi),由(you)靶(ba)標(biao)上(shang)特(te)征(zheng)點(dian)的(de)世(shi)界(jie)坐(zuo)標(biao)和(he)圖(tu)像(xiang)坐(zuo)標(biao),即(ji)可(ke)計(ji)算(suan)出(chu)攝(she)像(xiang)機(ji)的(de)內(nei)外(wai)參(can)數(shu)。
3.2基於2D平麵靶標的攝像機標定
這(zhe)是(shi)一(yi)種(zhong)適(shi)合(he)應(ying)用(yong)的(de)新(xin)型(xing)靈(ling)活(huo)方(fang)法(fa)。該(gai)方(fang)法(fa)要(yao)求(qiu)攝(she)像(xiang)機(ji)在(zai)兩(liang)個(ge)以(yi)上(shang)不(bu)同(tong)的(de)方(fang)位(wei)拍(pai)攝(she)一(yi)個(ge)平(ping)麵(mian)靶(ba)標(biao),該(gai)方(fang)法(fa)又(you)稱(cheng)為(wei)張(zhang)正(zheng)友(you)標(biao)定(ding)法(fa)。攝(she)像(xiang)機(ji)和(he)2D平麵靶標都可以自由移動,且內部參數始終不變,假定2D平麵靶標在世界坐標係中的Z=0那(na)麼(me),通(tong)過(guo)線(xian)性(xing)模(mo)型(xing)分(fen)析(xi)就(jiu)可(ke)計(ji)算(suan)出(chu)攝(she)像(xiang)機(ji)參(can)數(shu)的(de)優(you)化(hua)解(jie),然(ran)後(hou)用(yong)基(ji)幹(gan)最(zui)大(da)似(si)然(ran)法(fa)進(jin)行(xing)非(fei)線(xian)性(xing)求(qiu)精(jing)。這(zhe)個(ge)過(guo)程(cheng)中(zhong)得(de)出(chu)考(kao)慮(lv)鏡(jing)頭(tou)畸(ji)變(bian)的(de)目(mu)標(biao)函(han)數(shu)後(hou)就(jiu)可(ke)以(yi)求(qiu)出(chu)所(suo)需(xu)的(de)攝(she)像(xiang)機(ji)內(nei)、外(wai)部(bu)參(can)數(shu)。這(zhe)種(zhong)標(biao)定(ding)方(fang)法(fa)既(ji)具(ju)有(you)較(jiao)好(hao)的(de)魯(lu)棒(bang)性(xing),又(you)不(bu)需(xu)昂(ang)貴(gui)的(de)精(jing)製(zhi)標(biao)定(ding)塊(kuai),很(hen)有(you)實(shi)用(yong)性(xing)。但(dan)是(shi)張(zhang)正(zheng)友(you)方(fang)法(fa)在(zai)進(jin)行(xing)線(xian)性(xing)內(nei)外(wai)參(can)數(shu)估(gu)計(ji)時(shi),由(you)於(yu)假(jia)定(ding)模(mo)板(ban)圖(tu)像(xiang)上(shang)的(de)直(zhi)線(xian)經(jing)透(tou)視(shi)投(tou)影(ying)後(hou)仍(reng)然(ran)為(wei)直(zhi)線(xian),進(jin)而(er)進(jin)行(xing)圖(tu)像(xiang)處(chu)置(zhi),這(zhe)樣(yang),實(shi)際(ji)上(shang)會(hui)引(yin)入(ru)誤(wu)差(cha),所(suo)以(yi),嘎(ga)方(fang)法(fa)在(zai)廣(guang)角(jiao)鏡(jing)畸(ji)變(bian)比(bi)較(jiao)大(da)的(de)情(qing)況(kuang)誤(wu)差(cha)較(jiao)大(da)。
3.3基於徑向約束的攝像機標定
該方法的核心是先利用RA C徑向一致約束)條件用最小二乘法解超定線性方程,Tsai1986給出了一種基於徑向約束的兩步法標定方法。以求出除tτ(攝像機光軸方向的平移)外的其他像機外參數,然後再在攝像機有和無透鏡畸變等兩種情況下求解攝像機的其他參數。Tsaifangfadejingdubijiaogao,shiyongyujingmiceliang,dantaduishebeideyaoqiuyehengao,bushiyongyujiandandebiaoding。zhezhongfangfadejingdushiyishebeidejingduhefuzaduweidaijiade
4攝像機自標定方法
僅jin利li用yong攝she像xiang機ji在zai運yun動dong過guo程cheng中zhong周zhou圍wei環huan境jing圖tu像xiang與yu圖tu像xiang之zhi間jian的de對dui應ying關guan係xi來lai對dui攝she像xiang機ji進jin行xing的de標biao定ding的de方fang法fa稱cheng為wei攝she像xiang機ji自zi標biao定ding方fang法fa。目mu前qian已yi有you的de自zi標biao定ding技ji術shu大da致zhi可ke以yi分fen為wei基ji於yu主zhu動dong視shi覺jiao的de攝she像xiang機ji自zi標biao定ding技ji術shu、直接求解Kruppa方程的攝像機自標定方法、分層逐步標定法、基於二次曲麵的自標定方法等幾種。不依賴於標定參照物。
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