Transparent Layer Compensation at the Active Triangulation Systems

IFAC Pape sOnLine 52-27 (2019) 508–513 ScienceDi ec A ailable online a www.sciencedi ec .com 2405-8963 © 2019, IFAC (In e na ional Fede a ion o Au oma ic Con ol) Hos ing by Else ie L d. All igh s ese ed. Pee e iew unde esponsibili y o In e na ional Fede a ion o Au oma ic Con ol. 10.1016/j.i acol.2019.12.714 © 2019, IFAC (In e na ional Fede a ion o Au oma ic Con ol) Hos ing by Else ie L d. All igh s ese ed. 10.1016/j.i acol.2019.12.714 2405-8963 T anspa en Laye Compensa ion a he Ac i e T iangula ion Sys ems I. Janako a*, S. Sedi a**, P. Benes*** Depa men o Con ol and Ins umen a ion, Facul y o Elec ical Enginee ing and Communica ion, B no Uni e si y o Technology, B no, Czech Republic *(+420 541 146 390, e-mail: janako a@ eec. u b .cz) **(+420 541 146 418, e-mail: sedi a@ eec. u b .cz) ***(+420 541 141 152, e-mail: benes@ eec. u b .cz) Abs ac : The pape deals wi h an ac i e iangula ion echnique o non-con ac op ical measu emen o 3D p ope ies. The basic ea u es o he me hod - p inciple, ad an ages and disad an ages - a e desc ibed i s . Bu he main pa o he pape is conce ned wi h he impossibili y o using he basic p inciple o he me hod o measu ed objec s, which a e co e ed by a laye o anspa en ma e ial o unknown hickness. Mos o en i is a laye o oil o he p ese a ion o me al p oduc s. This laye dis o s he measu ed alue due o he ligh e ac ion. In his wo k, a me hod o elimina ing his dis o ion based on he use o wo senso s is p oposed. Expe imen al e i ica ion o his p oposal is also p esen ed. Keywo ds: 3D ision, op ical dis ance measu emen , ac i e iangula ion, image p ocessing, anspa en laye , oil compensa ion. 1. INTRODUCTION Op ical non-con ac dis an measu ing echniques ha e ound widesp ead use in many a eas, o example in a ic, a chi ec u e, obo na iga ion, objec ecogni ion, o in indus y in he p oduc ion inspec ion (Kalo á and Lisz wan, 2006). Thei expansion was suppo ed no only by he g ea de elopmen o echnics (elec onics, op ics), bu also by he p og ess made in echniques o da a and image p ocessing. The ad an ages o op ical me hods a e ha hey can be e y accu a e and as and agains o he p inciples ha a e non- con ac and non-des uc i e. I is also easie o econ igu e he sys em o ano he dimension o ype o p oduc s. In s anda d p ojec i e imaging, one dimension (usually he dep h in o ma ion) om 3D scenes is los . Wi hou he use o a special echnique, i is no possible o de e mine his in o ma ion e oac i ely. Fo una ely, depending on he speci ic equi emen s, di e en echnical app oaches can be used o op ical dis ance measu emen (Be ko ic and Sha i , 2012). The mos used app oaches a e based on one o h ee basic p inciples: iangula ion, ime-o - ligh (ToF) o op ical in e e ome y (Schwa e e al., 1999). Among he mos impo an pa ame e s o selec ing he mos app op ia e me hod include he equi ed ange o measu ed dis ances (dimensions o measu ed objec and he wo king dis ance), esolu ion, measu ing ime, opology (conca i ies, p o usions, edges) and su ace p ope ies ( oughness, specula e lec ions) o he measu ed objec , p ope ies o su ounding ligh ing, size o measu ing sys em, possibili ies o calib a ion, and also cos s. The mos widely used echnique o op ical o m measu emen s is iangula ion. T iangles a e he basis o many measu emen echniques. The ollowing a ian s, which look g ea ly di e en , bu use same p inciple can be dis inguished: ac i e iangula ion echniques wi h di e en illumina ion, passi e iangula ion echniques on he basis o digi al pho og amme y and s e eoscopy, heodoli e measu ing sys ems, shape om shading echniques and ocus echniques. The ac i e iangula ion echnique is e y o en used in p ac ice due o i s obus ness and e iciency, bu i also has se e al limi a ions and disad an ages. In pa icula , his a icle ocuses on he limi a ions o using his me hod o objec s ha a e co e ed wi h a anspa en laye , such as p ese ing oil. 2. ACTIVE TRIANGULATION 2.1 P inciple The ac i e iangula ion echnique is based on a pho og amme ic econs uc ion o he measu ed objec by illumina ion i s su ace and con empo aneous scanning by a senso (mos ly PSD module o CCD o CMOS came a). The p inciple o his echnique is shown in Fig. 1. The ligh sou ce, he de ec o and he illumina ed pa o he measu ed objec o m a iangle. The join b be ween he ligh sou ce and he de ec o is called a iangula ion op ical basis. The ligh sou ce ay angle α is ixed whe eas he angle on he de ec o side β changes depending on he a iable dis ance z and i is de ined by an illumina ed poin on he came a chip, espec i ely by a b igh poin on a p oduced image. I he in es iga ed objec is si ua ed a he away om he came a and ligh sou ce, he angle β is bigge so he e lec ed ligh ay is p ojec ed o he pixel mo e up (acco ding o he T anspa en Laye Compensa ion a he Ac i e T iangula ion Sys ems I. Janako a*, S. Sedi a**, P. Benes*** Depa men o Con ol and Ins umen a ion, Facul y o Elec ical Enginee ing and Communica ion, B no Uni e si y o Technology, B no, Czech Republic *(+420 541 146 390, e-mail: janako a@ eec. u b .cz) **(+420 541 146 418, e-mail: sedi a@ eec. u b .cz) ***(+420 541 141 152, e-mail: benes@ eec. u b .cz) Abs ac : The pape deals wi h an ac i e iangula ion echnique o non-con ac op ical measu emen o 3D p ope ies. The basic ea u es o he me hod - p inciple, ad an ages and disad an ages - a e desc ibed i s . Bu he main pa o he pape is conce ned wi h he impossibili y o using he basic p inciple o he me hod o measu ed objec s, which a e co e ed by a laye o anspa en ma e ial o unknown hickness. Mos o en i is a laye o oil o he p ese a ion o me al p oduc s. This laye dis o s he measu ed alue due o he ligh e ac ion. In his wo k, a me hod o elimina ing his dis o ion based on he use o wo senso s is p oposed. Expe imen al e i ica ion o his p oposal is also p esen ed. Keywo ds: 3D ision, op ical dis ance measu emen , ac i e iangula ion, image p ocessing, anspa en laye , oil compensa ion. 1. INTRODUCTION Op ical non-con ac dis an measu ing echniques ha e ound widesp ead use in many a eas, o example in a ic, a chi ec u e, obo na iga ion, objec ecogni ion, o in indus y in he p oduc ion inspec ion (Kalo á and Lisz wan, 2006). Thei expansion was suppo ed no only by he g ea de elopmen o echnics (elec onics, op ics), bu also by he p og ess made in echniques o da a and image p ocessing. The ad an ages o op ical me hods a e ha hey can be e y accu a e and as and agains o he p inciples ha a e non- con ac and non-des uc i e. I is also easie o econ igu e he sys em o ano he dimension o ype o p oduc s. In s anda d p ojec i e imaging, one dimension (usually he dep h in o ma ion) om 3D scenes is los . Wi hou he use o a special echnique, i is no possible o de e mine his in o ma ion e oac i ely. Fo una ely, depending on he speci ic equi emen s, di e en echnical app oaches can be used o op ical dis ance measu emen (Be ko ic and Sha i , 2012). The mos used app oaches a e based on one o h ee basic p inciples: iangula ion, ime-o - ligh (ToF) o op ical in e e ome y (Schwa e e al., 1999). Among he mos impo an pa ame e s o selec ing he mos app op ia e me hod include he equi ed ange o measu ed dis ances (dimensions o measu ed objec and he wo king dis ance), esolu ion, measu ing ime, opology (conca i ies, p o usions, edges) and su ace p ope ies ( oughness, specula e lec ions) o he measu ed objec , p ope ies o su ounding ligh ing, size o measu ing sys em, possibili ies o calib a ion, and also cos s. The mos widely used echnique o op ical o m measu emen s is iangula ion. T iangles a e he basis o many measu emen echniques. The ollowing a ian s, which look g ea ly di e en , bu use same p inciple can be dis inguished: ac i e iangula ion echniques wi h di e en illumina ion, passi e iangula ion echniques on he basis o digi al pho og amme y and s e eoscopy, heodoli e measu ing sys ems, shape om shading echniques and ocus echniques. The ac i e iangula ion echnique is e y o en used in p ac ice due o i s obus ness and e iciency, bu i also has se e al limi a ions and disad an ages. In pa icula , his a icle ocuses on he limi a ions o using his me hod o objec s ha a e co e ed wi h a anspa en laye , such as p ese ing oil. 2. ACTIVE TRIANGULATION 2.1 P inciple The ac i e iangula ion echnique is based on a pho og amme ic econs uc ion o he measu ed objec by illumina ion i s su ace and con empo aneous scanning by a senso (mos ly PSD module o CCD o CMOS came a). The p inciple o his echnique is shown in Fig. 1. The ligh sou ce, he de ec o and he illumina ed pa o he measu ed objec o m a iangle. The join b be ween he ligh sou ce and he de ec o is called a iangula ion op ical basis. The ligh sou ce ay angle α is ixed whe eas he angle on he de ec o side β changes depending on he a iable dis ance z and i is de ined by an illumina ed poin on he came a chip, espec i ely by a b igh poin on a p oduced image. I he in es iga ed objec is si ua ed a he away om he came a and ligh sou ce, he angle β is bigge so he e lec ed ligh ay is p ojec ed o he pixel mo e up (acco ding o he T anspa en Laye Compensa ion a he Ac i e T iangula ion Sys ems I. Janako a*, S. Sedi a**, P. Benes*** Depa men o Con ol and Ins umen a ion, Facul y o Elec ical Enginee ing and Communica ion, B no Uni e si y o Technology, B no, Czech Republic *(+420 541 146 390, e-mail: janako a@ eec. u b .cz) **(+420 541 146 418, e-mail: sedi a@ eec. u b .cz) ***(+420 541 141 152, e-mail: benes@ eec. u b .cz) Abs ac : The pape deals wi h an ac i e iangula ion echnique o non-con ac op ical measu emen o 3D p ope ies. The basic ea u es o he me hod - p inciple, ad an ages and disad an ages - a e desc ibed i s . Bu he main pa o he pape is conce ned wi h he impossibili y o using he basic p inciple o he me hod o measu ed objec s, which a e co e ed by a laye o anspa en ma e ial o unknown hickness. Mos o en i is a laye o oil o he p ese a ion o me al p oduc s. This laye dis o s he measu ed alue due o he ligh e ac ion. In his wo k, a me hod o elimina ing his dis o ion based on he use o wo senso s is p oposed. Expe imen al e i ica ion o his p oposal is also p esen ed. Keywo ds: 3D ision, op ical dis ance measu emen , ac i e iangula ion, image p ocessing, anspa en laye , oil compensa ion. 1. INTRODUCTION Op ical non-con ac dis an measu ing echniques ha e ound widesp ead use in many a eas, o example in a ic, a chi ec u e, obo na iga ion, objec ecogni ion, o in indus y in he p oduc ion inspec ion (Kalo á and Lisz wan, 2006). Thei expansion was suppo ed no only by he g ea de elopmen o echnics (elec onics, op ics), bu also by he p og ess made in echniques o da a and image p ocessing. The ad an ages o op ical me hods a e ha hey can be e y accu a e and as and agains o he p inciples ha a e non- con ac and non-des uc i e. I is also easie o econ igu e he sys em o ano he dimension o ype o p oduc s. In s anda d p ojec i e imaging, one dimension (usually he dep h in o ma ion) om 3D scenes is los . Wi hou he use o a special echnique, i is no possible o de e mine his in o ma ion e oac i ely. Fo una ely, depending on he speci ic equi emen s, di e en echnical app oaches can be used o op ical dis ance measu emen (Be ko ic and Sha i , 2012). The mos used app oaches a e based on one o h ee basic p inciples: iangula ion, ime-o - ligh (ToF) o op ical in e e ome y (Schwa e e al., 1999). Among he mos impo an pa ame e s o selec ing he mos app op ia e me hod include he equi ed ange o measu ed dis ances (dimensions o measu ed objec and he wo king dis ance), esolu ion, measu ing ime, opology (conca i ies, p o usions, edges) and su ace p ope ies ( oughness, specula e lec ions) o he measu ed objec , p ope ies o su ounding ligh ing, size o measu ing sys em, possibili ies o calib a ion, and also cos s. The mos widely used echnique o op ical o m measu emen s is iangula ion. T iangles a e he basis o many measu emen echniques. The ollowing a ian s, which look g ea ly di e en , bu use same p inciple can be dis inguished: ac i e iangula ion echniques wi h di e en illumina ion, passi e iangula ion echniques on he basis o digi al pho og amme y and s e eoscopy, heodoli e measu ing sys ems, shape om shading echniques and ocus echniques. The ac i e iangula ion echnique is e y o en used in p ac ice due o i s obus ness and e iciency, bu i also has se e al limi a ions and disad an ages. In pa icula , his a icle ocuses on he limi a ions o using his me hod o objec s ha a e co e ed wi h a anspa en laye , such as p ese ing oil. 2. ACTIVE TRIANGULATION 2.1 P inciple The ac i e iangula ion echnique is based on a pho og amme ic econs uc ion o he measu ed objec by illumina ion i s su ace and con empo aneous scanning by a senso (mos ly PSD module o CCD o CMOS came a). The p inciple o his echnique is shown in Fig. 1. The ligh sou ce, he de ec o and he illumina ed pa o he measu ed objec o m a iangle. The join b be ween he ligh sou ce and he de ec o is called a iangula ion op ical basis. The ligh sou ce ay angle α is ixed whe eas he angle on he de ec o side β changes depending on he a iable dis ance z and i is de ined by an illumina ed poin on he came a chip, espec i ely by a b igh poin on a p oduced image. I he in es iga ed objec is si ua ed a he away om he came a and ligh sou ce, he angle β is bigge so he e lec ed ligh ay is p ojec ed o he pixel mo e up (acco ding o he T anspa en Laye Compensa ion a he Ac i e T iangula ion Sys ems I. Janako a*, S. Sedi a**, P. Benes*** Depa men o Con ol and Ins umen a ion, Facul y o Elec ical Enginee ing and Communica ion, B no Uni e si y o Technology, B no, Czech Republic *(+420 541 146 390, e-mail: janako a@ eec. u b .cz) **(+420 541 146 418, e-mail: sedi a@ eec. u b .cz) ***(+420 541 141 152, e-mail: benes@ eec. u b .cz) Abs ac : The pape deals wi h an ac i e iangula ion echnique o non-con ac op ical measu emen o 3D p ope ies. The basic ea u es o he me hod - p inciple, ad an ages and disad an ages - a e desc ibed i s . Bu he main pa o he pape is conce ned wi h he impossibili y o using he basic p inciple o he me hod o measu ed objec s, which a e co e ed by a laye o anspa en ma e ial o unknown hickness. Mos o en i is a laye o oil o he p ese a ion o me al p oduc s. This laye dis o s he measu ed alue due o he ligh e ac ion. In his wo k, a me hod o elimina ing his dis o ion based on he use o wo senso s is p oposed. Expe imen al e i ica ion o his p oposal is also p esen ed. Keywo ds: 3D ision, op ical dis ance measu emen , ac i e iangula ion, image p ocessing, anspa en laye , oil compensa ion. 1. INTRODUCTION Op ical non-con ac dis an measu ing echniques ha e ound widesp ead use in many a eas, o example in a ic, a chi ec u e, obo na iga ion, objec ecogni ion, o in indus y in he p oduc ion inspec ion (Kalo á and Lisz wan, 2006). Thei expansion was suppo ed no only by he g ea de elopmen o echnics (elec onics, op ics), bu also by he p og ess made in echniques o da a and image p ocessing. The ad an ages o op ical me hods a e ha hey can be e y accu a e and as and agains o he p inciples ha a e non- con ac and non-des uc i e. I is also easie o econ igu e he sys em o ano he dimension o ype o p oduc s. In s anda d p ojec i e imaging, one dimension (usually he dep h in o ma ion) om 3D scenes is los . Wi hou he use o a special echnique, i is no possible o de e mine his in o ma ion e oac i ely. Fo una ely, depending on he speci ic equi emen s, di e en echnical app oaches can be used o op ical dis ance measu emen (Be ko ic and Sha i , 2012). The mos used app oaches a e based on one o h ee basic p inciples: iangula ion, ime-o - ligh (ToF) o op ical in e e ome y (Schwa e e al., 1999). Among he mos impo an pa ame e s o selec ing he mos app op ia e me hod include he equi ed ange o measu ed dis ances (dimensions o measu ed objec and he wo king dis ance), esolu ion, measu ing ime, opology (conca i ies, p o usions, edges) and su ace p ope ies ( oughness, specula e lec ions) o he measu ed objec , p ope ies o su ounding ligh ing, size o measu ing sys em, possibili ies o calib a ion, and also cos s. The mos widely used echnique o op ical o m measu emen s is iangula ion. T iangles a e he basis o many measu emen echniques. The ollowing a ian s, which look g ea ly di e en , bu use same p inciple can be dis inguished: ac i e iangula ion echniques wi h di e en illumina ion, passi e iangula ion echniques on he basis o digi al pho og amme y and s e eoscopy, heodoli e measu ing sys ems, shape om shading echniques and ocus echniques. The ac i e iangula ion echnique is e y o en used in p ac ice due o i s obus ness and e iciency, bu i also has se e al limi a ions and disad an ages. In pa icula , his a icle ocuses on he limi a ions o using his me hod o objec s ha a e co e ed wi h a anspa en laye , such as p ese ing oil. 2. ACTIVE TRIANGULATION 2.1 P inciple The ac i e iangula ion echnique is based on a pho og amme ic econs uc ion o he measu ed objec by illumina ion i s su ace and con empo aneous scanning by a senso (mos ly PSD module o CCD o CMOS came a). The p inciple o his echnique is shown in Fig. 1. The ligh sou ce, he de ec o and he illumina ed pa o he measu ed objec o m a iangle. The join b be ween he ligh sou ce and he de ec o is called a iangula ion op ical basis. The ligh sou ce ay angle α is ixed whe eas he angle on he de ec o side β changes depending on he a iable dis ance z and i is de ined by an illumina ed poin on he came a chip, espec i ely by a b igh poin on a p oduced image. I he in es iga ed objec is si ua ed a he away om he came a and ligh sou ce, he angle β is bigge so he e lec ed ligh ay is p ojec ed o he pixel mo e up (acco ding o he T anspa en Laye Compensa ion a he Ac i e T iangula ion Sys ems I. Janako a*, S. Sedi a**, P. Benes*** Depa men o Con ol and Ins umen a ion, Facul y o Elec ical Enginee ing and Communica ion, B no Uni e si y o Technology, B no, Czech Republic *(+420 541 146 390, e-mail: janako a@ eec. u b .cz) **(+420 541 146 418, e-mail: sedi a@ eec. u b .cz) ***(+420 541 141 152, e-mail: benes@ eec. u b .cz) Abs ac : The pape deals wi h an ac i e iangula ion echnique o non-con ac op ical measu emen o 3D p ope ies. The basic ea u es o he me hod - p inciple, ad an ages and disad an ages - a e desc ibed i s . Bu he main pa o he pape is conce ned wi h he impossibili y o using he basic p inciple o he me hod o measu ed objec s, which a e co e ed by a laye o anspa en ma e ial o unknown hickness. Mos o en i is a laye o oil o he p ese a ion o me al p oduc s. This laye dis o s he measu ed alue due o he ligh e ac ion. In his wo k, a me hod o elimina ing his dis o ion based on he use o wo senso s is p oposed. Expe imen al e i ica ion o his p oposal is also p esen ed. Keywo ds: 3D ision, op ical dis ance measu emen , ac i e iangula ion, image p ocessing, anspa en laye , oil compensa ion. 1. INTRODUCTION Op ical non-con ac dis an measu ing echniques ha e ound widesp ead use in many a eas, o example in a ic, a chi ec u e, obo na iga ion, objec ecogni ion, o in indus y in he p oduc ion inspec ion (Kalo á and Lisz wan, 2006). Thei expansion was suppo ed no only by he g ea de elopmen o echnics (elec onics, op ics), bu also by he p og ess made in echniques o da a and image p ocessing. The ad an ages o op ical me hods a e ha hey can be e y accu a e and as and agains o he p inciples ha a e non- con ac and non-des uc i e. I is also easie o econ igu e he sys em o ano he dimension o ype o p oduc s. In s anda d p ojec i e imaging, one dimension (usually he dep h in o ma ion) om 3D scenes is los . Wi hou he use o a special echnique, i is no possible o de e mine his in o ma ion e oac i ely. Fo una ely, depending on he speci ic equi emen s, di e en echnical app oaches can be used o op ical dis ance measu emen (Be ko ic and Sha i , 2012). The mos used app oaches a e based on one o h ee basic p inciples: iangula ion, ime-o - ligh (ToF) o op ical in e e ome y (Schwa e e al., 1999). Among he mos impo an pa ame e s o selec ing he mos app op ia e me hod include he equi ed ange o measu ed dis ances (dimensions o measu ed objec and he wo king dis ance), esolu ion, measu ing ime, opology (conca i ies, p o usions, edges) and su ace p ope ies ( oughness, specula e lec ions) o he measu ed objec , p ope ies o su ounding ligh ing, size o measu ing sys em, possibili ies o calib a ion, and also cos s. The mos widely used echnique o op ical o m measu emen s is iangula ion. T iangles a e he basis o many measu emen echniques. The ollowing a ian s, which look g ea ly di e en , bu use same p inciple can be dis inguished: ac i e iangula ion echniques wi h di e en illumina ion, passi e iangula ion echniques on he basis o digi al pho og amme y and s e eoscopy, heodoli e measu ing sys ems, shape om shading echniques and ocus echniques. The ac i e iangula ion echnique is e y o en used in p ac ice due o i s obus ness and e iciency, bu i also has se e al limi a ions and disad an ages. In pa icula , his a icle ocuses on he limi a ions o using his me hod o objec s ha a e co e ed wi h a anspa en laye , such as p ese ing oil. 2. ACTIVE TRIANGULATION 2.1 P inciple The ac i e iangula ion echnique is based on a pho og amme ic econs uc ion o he measu ed objec by illumina ion i s su ace and con empo aneous scanning by a senso (mos ly PSD module o CCD o CMOS came a). The p inciple o his echnique is shown in Fig. 1. The ligh sou ce, he de ec o and he illumina ed pa o he measu ed objec o m a iangle. The join b be ween he ligh sou ce and he de ec o is called a iangula ion op ical basis. The ligh sou ce ay angle α is ixed whe eas he angle on he de ec o side β changes depending on he a iable dis ance z and i is de ined by an illumina ed poin on he came a chip, espec i ely by a b igh poin on a p oduced image. I he in es iga ed objec is si ua ed a he away om he came a and ligh sou ce, he angle β is bigge so he e lec ed ligh ay is p ojec ed o he pixel mo e up (acco ding o he T anspa en Laye Compensa ion a he Ac i e T iangula ion Sys ems I. Janako a*, S. Sedi a**, P. Benes*** Depa men o Con ol and Ins umen a ion, Facul y o Elec ical Enginee ing and Communica ion, B no Uni e si y o Technology, B no, Czech Republic *(+420 541 146 390, e-mail: janako a@ eec. u b .cz) **(+420 541 146 418, e-mail: sedi a@ eec. u b .cz) ***(+420 541 141 152, e-mail: benes@ eec. u b .cz) Abs ac : The pape deals wi h an ac i e iangula ion echnique o non-con ac op ical measu emen o 3D p ope ies. The basic ea u es o he me hod - p inciple, ad an ages and disad an ages - a e desc ibed i s . Bu he main pa o he pape is conce ned wi h he impossibili y o using he basic p inciple o he me hod o measu ed objec s, which a e co e ed by a laye o anspa en ma e ial o unknown hickness. Mos o en i is a laye o oil o he p ese a ion o me al p oduc s. This laye dis o s he measu ed alue due o he ligh e ac ion. In his wo k, a me hod o elimina ing his dis o ion based on he use o wo senso s is p oposed. Expe imen al e i ica ion o his p oposal is also p esen ed. Keywo ds: 3D ision, op ical dis ance measu emen , ac i e iangula ion, image p ocessing, anspa en laye , oil compensa ion. 1. INTRODUCTION Op ical non-con ac dis an measu ing echniques ha e ound widesp ead use in many a eas, o example in a ic, a chi ec u e, obo na iga ion, objec ecogni ion, o in indus y in he p oduc ion inspec ion (Kalo á and Lisz wan, 2006). Thei expansion was suppo ed no only by he g ea de elopmen o echnics (elec onics, op ics), bu also by he p og ess made in echniques o da a and image p ocessing. The ad an ages o op ical me hods a e ha hey can be e y accu a e and as and agains o he p inciples ha a e non- con ac and non-des uc i e. I is also easie o econ igu e he sys em o ano he dimension o ype o p oduc s. In s anda d p ojec i e imaging, one dimension (usually he dep h in o ma ion) om 3D scenes is los . Wi hou he use o a special echnique, i is no possible o de e mine his in o ma ion e oac i ely. Fo una ely, depending on he speci ic equi emen s, di e en echnical app oaches can be used o op ical dis ance measu emen (Be ko ic and Sha i , 2012). The mos used app oaches a e based on one o h ee basic p inciples: iangula ion, ime-o - ligh (ToF) o op ical in e e ome y (Schwa e e al., 1999). Among he mos impo an pa ame e s o selec ing he mos app op ia e me hod include he equi ed ange o measu ed dis ances (dimensions o measu ed objec and he wo king dis ance), esolu ion, measu ing ime, opology (conca i ies, p o usions, edges) and su ace p ope ies ( oughness, specula e lec ions) o he measu ed objec , p ope ies o su ounding ligh ing, size o measu ing sys em, possibili ies o calib a ion, and also cos s. The mos widely used echnique o op ical o m measu emen s is iangula ion. T iangles a e he basis o many measu emen echniques. The ollowing a ian s, which look g ea ly di e en , bu use same p inciple can be dis inguished: ac i e iangula ion echniques wi h di e en illumina ion, passi e iangula ion echniques on he basis o digi al pho og amme y and s e eoscopy, heodoli e measu ing sys ems, shape om shading echniques and ocus echniques. The ac i e iangula ion echnique is e y o en used in p ac ice due o i s obus ness and e iciency, bu i also has se e al limi a ions and disad an ages. In pa icula , his a icle ocuses on he limi a ions o using his me hod o objec s ha a e co e ed wi h a anspa en laye , such as p ese ing oil. 2. ACTIVE TRIANGULATION 2.1 P inciple The ac i e iangula ion echnique is based on a pho og amme ic econs uc ion o he measu ed objec by illumina ion i s su ace and con empo aneous scanning by a senso (mos ly PSD module o CCD o CMOS came a). The p inciple o his echnique is shown in Fig. 1. The ligh sou ce, he de ec o and he illumina ed pa o he measu ed objec o m a iangle. The join b be ween he ligh sou ce and he de ec o is called a iangula ion op ical basis. The ligh sou ce ay angle α is ixed whe eas he angle on he de ec o side β changes depending on he a iable dis ance z and i is de ined by an illumina ed poin on he came a chip, espec i ely by a b igh poin on a p oduced image. I he in es iga ed objec is si ua ed a he away om he came a and ligh sou ce, he angle β is bigge so he e lec ed ligh ay is p ojec ed o he pixel mo e up (acco ding o he I. Janako a e al. / IFAC Pape sOnLine 52-27 (2019) 508–513 509 simpli ied Fig. 1). In his way, he dis ance o he objec can be ob ained jus om he posi ion o he ligh poin in he image. Howe e , wi h he α angle o he han 90 °, i should be bo ne in mind ha when he objec 's dis ance changes, he x posi ion on he su ace being measu ed also changes. The ela ionship be ween he coo dina e in he image and he dis ance can be de e mined by calcula ion (based on he knowledge o he geome y and pa ame e s o he came a and lens) o due o calib a ion. Fig. 1. P inciple o he iangula ion me hod (1D a ian ) The measu emen unce ain y in z is in e sely p opo ional o bo h he came a baseline and he ocal leng h o he lens, bu di ec ly p opo ional o he squa e o he dis ance (Kalo á and Lisz wan, 2005). Un o una ely, and b canno be made as la ge as desi ed. The baseline is limi ed mainly by he mechanical cons uc ion (s abili y o he whole sys em dec eases as b inc eases), and by shadow e ec s (sel - occlusion p oblems inc ease wi h b) (Be aldin e al., 2003). The size o he ocal leng h is limi ed by he limi ed dimensions o he o e ed de ec o s. Mo eo e , wi h inc easing he de ec o 's ield o iew dec eases and hus he ange in he Z-axis also dec eases. 2.2 Va ian s Depending on he ligh sou ce used o ma k he objec , h ee a ian s can be dis inguished: a ligh poin , a ligh s ipe, and a s uc u ed ligh . The dimension o he used ligh de e mines he dimension and he numbe o ob ained poin s. When using he ligh poin , only one coo dina e ( ypically dis ance, dep h, o z coo dina e) o one poin is de e mined a a ime, he e o e his a ian is called 1D iangula ion. The ad an age o his op ion is ha a line came a wi h a usually highe ho izon al esolu ion and high line scan equency can be used. When he ligh s ipe (2D iangula ion) is used, wo coo dina es a e de e mined a once and he numbe o measu ed poin s depends on he came a's pixel esolu ion (a p o ile is measu ed). The ad an age o using s uc u ed ligh - 3D iangula ion (Geng, 2011) is ha he comple e 3D coo dina es o he whole objec can be de e mined in block ( he numbe o poin s depends on he used pa e n and he came a esolu ion; he dimensions o he measu ed pa o he objec a e de ined by he selec ed chip and lens and o e all geome y). I i is equi ed o speci y mo e coo dina es ( o 1D and 2D a ian s) o mo e poin s, i is necessa y o ensu e scanning (mo emen o he measu ing sys em o objec in one o wo axes). Con en ional ligh sou ces can be used o op ical iangula ion, bu lase sou ces ha e unique ad an ages o 3D imaging (Amann e al., 2001). Abo e all, i is high b igh ness, cohe ence and monoch oma ism, and low di e gence. 2.3 Ad an ages and disad an ages Ac i e iangula ion sys ems a e ela i ely simple, obus and e icien . The ad an age is ha hey can ope a e o e a wide ange o dis ances. Lase -based op ical displacemen senso s using a e y small spo which enables measu emen s on he e y small pa s. The 3D e sion can measu e an en i e objec in one ins an om one ame. The 2D a ian is o en used on p oduc ion lines, whe e scanning and measu emen o he whole objec a e ensu ed hanks o he ansla ional mo emen below he measu ing uni . The a ian wi h poin lase and line came a is e y as , wi h a sampling a e o 100 kHz commonly achie ed. High measu ing a es a e equi ed o he as mo ing a ge s o measu emen s on di icul su aces. Comme cial lase scanne s a e e y obus wi h compac dimensions. Despi e hei e y small dimensions, some se ies ha e a ully in eg a ed con olle . As a esul , simple, apid ins alla ion and wi ing a e possible. The senso s can be in eg a ed easily e en in o es ic ed ins alla ion space. The comp ehensi e solu ion enables easy measu emen con ol, synch oniza ion wi h o he elemen s as well as be ween se e al iangula ion senso s (e.g. di e en ial hickness measu emen ) and usually a clea con ol and e alua ion applica ion. The senso s can be also equipped wi h di e en ou pu s o ul il indus ial use equi emen s. The pi alls o ac i e iangula ion echniques a e gene ally o e alua e pa s o he objec ha a e no di ec ly isible by he came a o illumina ed by he ligh sou ce. Su ace opology and geome y o eal physical objec s can be qui e complex, wi h mul iple holes, conca i ies, p o usions and edges. P oblems also b ing su aces pe pendicula o he image plane and su aces pa allel o he ligh sou ce. The measu emen quali y is also in luenced by he su ace p ope ies o he measu ed objec . Essen ial a e especially su ace oughness, e lec ance, and colou . Howe e , oday's sys ems a e capable o measu ing e en complica ed su aces, such as shiny me allic ma e ials o con a iwise ubbe . The exposu e ime o he amoun o ligh p oduced by he lase is op imally ma ched o he e lec ion cha ac e is ics o he a ge su ace. New possibili ies also include he use o a blue lase (nex o mo e common ed). Due o i s sho e wa eleng h, i does no pene a e he a ge su ace, p ojec ing a small ligh spo on he su ace and he e o e p o iding s able and p ecise esul s. This echnology is p e e ably used wi h o ganic and (semi-) anspa en objec s, as well as o ed-ho glowing me als. Ano he p oblem, ha was encoun e ed when es ing he lase sys em o check he dimensions o p oduc s, can be caused by he hin laye o some anspa en ma e ial on he p oduc s, whe e he measu ed alues a e dis o ed due o he e ac ion o he ligh in ha laye . 510 I. Janako a e al. / IFAC Pape sOnLine 52-27 (2019) 508–513 3. PROBLEM DEFINITION The ask o he p oposed sys em was o measu e he pa ame e s o he pa icula me al pa s o he axial bea ings and, based on he measu emen s, o check whe he some pa s we en' con used. Indi idual ypes o bea ings di e in he combina ion o hei dimensions (heigh , inne and ou e diame e , aceway pa ame e s) e en in he o de o only a ew mic ome e s, so i was necessa y o ensu e e y accu a e measu emen s. Un o una ely, he con ol measu ing sys em had o be placed un il jus be o e assembling all pa s, whe e he pa s a e oil-p ese ed. Due o he me hod o p ese a ion by dipping and ee d ipping o he componen s in an unde ined posi ion, he laye hickness is no uni o m and canno be p ede e mined. Se e al app oaches we e conside ed o measu emen . One op ion was o use he 1D o 2D lase iangula ion sys em. Howe e , he p oblem is ha he pa ially anspa en laye o p ese a i e oil causes no only dis u bing ligh e lec ions om i s su ace and also educes he in ensi y o ecei ed ligh , bu abo e all, i causes a change in he di ec ion o he ligh beam a he in e ace be ween wo media wi h di e en e ac i e indices. I he lase beam passes om ambien ai o an op ically dense oil medium ( he e ac i e index o he oil is abou 1.5), he angle o e ac ion is less han he angle o incidence - he ay in he highe -index medium is close o he no mal. Respec i ely, when eco ding he ligh e lec ed om he me al su ace, he opposi e phenomenon is obse ed. Fo he sake o cla i y, he p oblem is shown in Fig. 2 in a simple and mo e a ou able si ua ion, whe e he lase beam is pe pendicula o he su ace ( he e o e he e is no double e ac ion) and pa allel p ojec ion is used. Fig. 2. The dis ance measu ing p oblem o componen s wi h he oil laye Poin A in Fig. 2 indica es he loca ion whe e he ligh beam would be p ojec ed i he e we e no oil laye s. Con e sely, poin B ep esen s he illumina ed spo on he chip a e e ac ion o he ligh in he uppe anspa en laye . Due o he ac ha he p ojec ion is shi ed on he chip, he w ong dis ance l B is de e mined agains he eal dis ance l o he me al su ace o he bea ing om he lase . The magni ude o he e o is di ec ly p opo ional o he angle be ween he came a's op ical axis and he no mal o he measu ed su ace α, as well as o he e ac i e index o he laye n 2 and o i s hickness . T igonome ic unc ions can be used o calcula e he e o ( o simplici y, a elecen ic lens wi h pa allel beams is conside ed, as in Fig. 2): α β g g e ⋅ −= , (1) whe e angle β is gi en by Snell’s law: βα sinsin 21 ⋅=⋅ nn , (2) Fo example, o he angle α = 50° and he oil laye ( n 2 = 1.5) wi h he hickness o only 0.1 mm, he e o is g ea e han 0.05 mm, so o he co ec dis inc ion o bea ing ypes is his e o e y signi ican . The hickness o he oil laye may a y in di e en pa s o he bea ing ing due o he su ace ension and unning down oil in o he bea ing aceway (see Fig. 2), and hus depends also on he size and shape o he ing. In addi ion, he oil hickness can be changed by u he manipula ion, o example by g ipping he ing in he hand. Howe e , due o he unknown ac ual oil hickness, i is no possible o de e mine he amoun o dis o ion, espec i ely enqui ed bea ing heigh , om only one measu emen . 4. SUGGESTED SOLUTION The p oposed solu ion o he p oblem desc ibed in he p e ious chap e is o use wo senso s ( wo came as) each wi h he di e en angle o he lase beam. The p inciple is shown in Fig. 3. Fig. 3. P inciple o he p oposed solu ion using wo senso s Each sepa a e measu ing uni , composed o he came a and he lase (whe e he lase can be common o bo h uni s) measu es, due o di e en iewing angle α i , he di e sely dis o ed coo dina es z ei ( i is he index o measu emen ) iiii iii i e ezz nn z +== ), ,,,( 21 α . (3) I. Janako a e al. / IFAC Pape sOnLine 52-27 (2019) 508–513 511 The medium n 1 , whe e he whole measu ing uni is loca ed, is su ounding ai so n 11 = n 12 = n 1 = 1 . The medium n 2 ep esen s he anspa en laye abo e he measu ed objec (in ou case oil, whe e n 2 is app oxima ely 1.5) and i is uni o m o bo h measu emen s ( n 21 = n 22 = n 2 ). In he nea neighbou hood o he measu emen , unknown hicknesses o he laye can also be conside ed iden ical ( 1 = 2 = ). And o cou se, equal is he second unknown in ou ask - he heigh o he objec abo e he pad z 1 = z 2 = z . I he angles α i and index n 2 a e known, wo equa ions o wo unknowns can be cons uc ed based on wo measu emen s and z and can be de e mined simul aneously. The ad an age is ha he same sys em can be used o ano he ype o ask wi h wo unknowns. Fo example, he laye e ac i e index o he unknown hickness can be de e mined o ice e sa. 5. EXPERIMENTAL VERIFICATION A labo a o y iangula ion wo kplace wi h wo came as was assembled o e i y he p oposed solu ion. The design was es ed on he es ask o measu ing he pa ame e s o axial bea ings. Fo he measu emen , he wo-dimensional a ian wi h he line lase was chosen o measu e he en i e bea ing p o ile a once. The a angemen o he indi idual componen s o he assembled expe imen al wo kplace is shown in he pho og aph (Fig. 4) and he ske ch (Fig.5). The bea ing was placed on a la backpla e wi h he aceway poin ing upwa ds and was pushed o wo chocks (diame e 6 mm and dis ance 25 mm). This ensu es p ecise posi ioning, cen e ing o he ing and, a he same ime, he ou e diame e o he ing can be de e mined om he size o inse ion o he ing be ween he s ops (p o ile posi ion wi hin he measu ed ield). The line lase was moun ed abo e he pad o shine pe pendicula o he pad, and he lase s ipe illumina ed he space exac ly be ween he s oppe s. The op ical plane o he lase hen passes h ough he symme y axis o he ing. The came as we e moun ed sepa a ely on he s ands and we e o ien ed so ha he lase ack e lec ed om he pad was a he bo om o he cap u ed images and was pa allel o he Y-axis o he images and, o cou se, o wa ch he a ea a he ing p o ile. Fig. 4. Pho og aph o he assembled expe imen al wo kplace Fig. 5. Schema ic ske ch o he a angemen o he indi idual componen s o he designed measu ing sys em Two iden ical CCD came as we e used (Imaging Sou ce DFK 41BU02 wi h 1/2" chip size and 1280x960 pixel esolu ion). A na owband il e was inse ed in on o each chip o il e ou ligh componen s o he han he wa eleng h o he lase used (650 nm). Bo h came as we e supplemen ed wi h he same lenses (VICO imaging MFA1-230-5M35 wi h 35 mm ocal leng h and 1:1.4 ape u e). A dis ance ing has always been inse ed be ween he came a and he lens o educe he wo king dis ance. The came a dis ance was adjus ed o ob ain he necessa y X-axis ange (app oxima ely 26 mm). The use o a classic ixed ocus lens (endocen ic) is no he mos sui able o measu emen asks like his. A elecen ic lens and/o a lens using he Scheimp lug p inciple o oblique plane sensing would be p e e able. Howe e , such wo iden ical lenses we e no a ailable o es ing. I is also possible o selec mo e sui able came as wi h la ge chip and esolu ion o eal applica ion. The angle be ween he op ical axis o he i s came a and he lase plane was app oxima ely 30° (α 1 = 30°) and o he second came a α 2 = 55°. These angles we e chosen as a comp omise be ween he desi ed ange and esolu ion in Z-axis, he quali y o he e lec ed ligh s ip in he cap u ed images, and a su icien di e ence be ween he wo angles o success ul compensa ion o he oil laye . The measu ing sys em o he assembled wo kplace had a pixel esolu ion in he X-axis o app oxima ely 20 µm and in he Z-axis o he i s came a 40 µm and o he second 24 µm. The con e sion ela ions be ween he image coo dina es and he eal coo dina e sys em in oduced o he measu ed objec can be de e mined by calcula ion, bu i is necessa y o know p ecisely all he equi ed inpu pa ame e s (e.g. pa ame e s o came as and lenses, o ien a ion o came as, e c.) and in case o some changes du ing use o measu ing sys em i is necessa y o measu e all a iables again and ecalcula e he ela ionships. O i is possible o de e mine he in e ela ionships o indi idual iangula ion sys ems (came a, lase , and measu ed objec ) by calib a ion. I a sui able au oma ic p ocedu e and solu ion o calib a ion a e designed, his app oach is mo e app op ia e because i allows a con inuous ecalib a ion o he en i e measu ing sys em a e e y change o e en p e en i ely (a sligh change in he ela ionship can also occu due o en i onmen al in luences, e.g. empe a u e). Calib a ion o expe imen al sys ems was 512 I. Janako a e al. / IFAC Pape sOnLine 52-27 (2019) 508–513 pe o med on se e al ings whose eal spa ial coo dina es we e sub ac ed om p e iously measu ed p o iles by ScanCon ol 2900-25/BL scanne . Mo e app op ia e, e en wi h espec o he planned ecalib a ion, would be o use a speci ically designed o his pu pose (sui able dimensions and dis ibu ion o calib a ion poin s) and p ecisely manu ac u ed calib a ion objec ha would bes co e he en i e equi ed space wi h he calib a ion poin s. Fo he se o poin s wi h known spa ial coo dina es (x, z) a e assigned co esponding coo dina es (u, ) in he images. Two (one o each came a) ans o ma ion ma ices (size 3x3) de e mined by he leas squa es me hod a e he esul o he calib a ion. Simila ly, he con e sion ela ionship be ween he oil hickness and he e o p oduced can be de e mined by calcula ion o calib a ion. Fo he same eason, howe e , hese ela ionships we e again de e mined by calib a ion. Also because he e ac i e index o he pa icula used oil was no exac ly known. Fo his pu pose, he oil- ee ings we e i s measu ed and hen he oil o unknown hickness was applied o hem and he di e ences in alues we e de e mined by e-measu emen . Based on se e al measu emen s, he cons an K ep esen ing he a e age e o a io o he second and he i s came a K = e 2 / e 1 was de e mined (a he cos o some inaccu acy in endocen ic lenses). The ad an age o his app oach o calib a ion is ha he e is no need o know he cu en oil hickness. Fo he pu pose o measu ing bea ing p o iles, undis o ed as well as dis o ed by oil laye , a p og am o sub-pixel lase line de ec ion and da a il e ing had o be c ea ed. An example o lase ack e alua ion is shown in Fig. 6. As can be seen om he p esen ed igu e, he quali y o lase ace acing is highly dependen on he su ace o he objec being measu ed. P oblems a e caused by une en su aces, gla e, less e lec i e and inclined su aced in he aceway, and shadows be ween he bea ing and base (in he case o elecen ic lens use, blind spo s and shadows should no be c ea ed). A e applying he oil, he lase ack, especially in he aceway, whe e he la ges amoun o oil ends o be, is less no iceable and mo e blu ed. The quali y o lase acking can be imp o ed by aking images wi h se e al di e en exposu e imes and selec ing he mos app op ia e image o each bea ing egion. Fig. 6. The esul o he lase ack de ec ion p og am A e lase ack de ec ion, he pixel posi ions o he line a e ans o med a spa ial coo dina es based on calib a ion da a o each came a. The ollowing igu e shows wo measu ed p o iles o he same ing wi hou an oil laye om he i s and he second came a. Ideally (especially pe ec line de ec ion and calib a ion), bo h p o iles should be he same a e ans o ma ion. Howe e , due o e.g. e lec ions, limi ed and unequal came a esolu ion, e c., he eal ob ained p o iles a e sligh ly di e en . The di e ences a e shown by he g een do s in Fig. 7. In his pa icula case, he a e age p o iles di e ence is 6.5 µm, he s anda d de ia ion is 12.7 µm. Fig. 7. P o ile measu ed by i s came a (blue) and second came a ( ed) and di e ence o alues (g een) A e applying he oil, as expec ed, he measu ed da a is de o med by he oil laye (ligh e ac ion). The measu ed p o iles o he same oil- ee (blue) and oiled ( ed) bea ing a e shown in he ollowing igu e. As you can see om he di e ence o alues (g een), he e o a he deepes poin o he aceway is o e 200 µm o he i s came a and nea ly 300 µm o he second (due o he la ge came a-lase angle). This co esponds o he oil hickness o app oxima ely 0.55 mm. Howe e , i should be no ed ha his oil hickness is un ealis ically high and se es only o p esen a ion. The usual oil hickness a e p ese a ion and d ipping in ope a ion is up o abou 100 µm. Fig. 8. Measu ed p o ile o he same bea ing wi hou oil (blue), a e oil applica ion ( ed) and di e ence (g een) When wo oil-coa ed ing p o iles a e measu ed wi h came as a di e en angles, he eal bea ing p o ile can be calcula ed based also on he de o med da a hanks o he con e sion ela ionships speci ied by calib a ion ( o each X-coo dina e, he Z-coo dina e can be de e mined wha would be wi hou oil). The calcula ion can be done using he o mula: 1 21 − − ⋅ = K zKz z ee , (4) I. Janako a e al. / IFAC Pape sOnLine 52-27 (2019) 508–513 513 The esul i g aphed in Fig. 9, whe ein he calcula ed oil laye compensa ion p o ile is shown in black. Fo he sake o cla i y, he g aph is supplemen ed by p o iles measu ed by bo h came as wi hou he oil laye (blue and ed wa e o ms as in Fig. 7) and by he di e ence be ween he compensa ed p o ile and he oil- ee p o ile om he i s came a (g een wa e o m). Al hough he dispe sion o he di e ence be ween he p o ile o he i s oil- ee came a and he compensa ed p o ile is la ge in his case, as shown by he la ge s anda d de ia ion alue o 52.8 µm, howe e , he a e age di e ence is only -2.7 µm. Fig. 9. Compensa ed p o ile (black) and di e ence (g een) om he p o ile wi hou oil om i s came a (blue) The oil laye , i no compensa ed, has a undamen al in luence on he de e mina ion o he basic bea ing pa ame e s - ing heigh and aceway adius, espec i ely aceway dep h. Sepa a e algo i hms we e p og ammed o de e mine hese pa ame e s. Fo example, he ing heigh is de e mined by app oxima ion o da a a he ing's op edges and a he basepla e by he s aigh lines. The da a in he aceway, on he o he hand, is in e laced wi h a ci cle. I he bea ing dimensions we e measu ed wi h only one iangula ion sys em, wi hou he possibili y o elimina ing he e ec o he laye , he measu ed bea ing heigh would be highe han he eali y and he aceway adius would also be la ge . Fig. 10 shows a de ail o p o ile wi h oil wi hou ( ed) and a e (black) compensa ion. The calcula ed aceway adii de e mined by i ing he aceway poin s wi h he ci cle a e indica ed by he same colou . The blue pa o he ci cle indica es he adius speci ied o he oil- ee bea ing. I can be seen ha while he compensa ed p o ile has a g ea e dispe sion o alues, he alues be e ollow he eal shape Fig. 10. Raceway adius de e mina ion - p o ile wi hou ( ed) and a e (black) compensa ion o he aceway. Howe e , he sho sec ion o he ci cle is no su icien o accu a ely de e mine he diame e o he aceway bu will be used o de e mine i s dep h and o he bea ing pa ame e s. 6. CONCLUSIONS The a icle deals wi h he undamen al limi a ion o he applica ion o he basic simple p inciple o he ac i e iangula ion me hod o objec s ha a e co e ed by some anspa en laye (e.g. p ese ing oil, lub ican , wa e ). Fo his eason, he inno a i e sys em o measu e 3D pa ame e s o objec s h ough his laye has been designed. The basic idea is o use wo coope a ing senso s each wi h he di e en angle o he lase . The ad an age is ha he same sys em can be used o ano he ype o ask wi h wo unknowns (e.g. he laye hickness o unknown e ac i e index o ice e sa). Al hough he mos app op ia e ha dwa e was no a ailable o he expe imen s, and e en he so wa e could no ye be esol ed a he le el o he de elopmen o a comme cial inished de ice, ne e heless he pe o med es s demons a e ha he p oposed p inciple is co ec and ha his p ocedu e is applicable o elimina e he anspa en laye . ACKNOWLEDGEMENT The comple ion o his pape was made possible by he g an TH02010830 – “Au oma ion, measu emen and moni o ing o assembly p ocesses” which is unded by Technology Agency o he Czech Republic - p og amme EPSILON and by he g an No. FEKT-S-17-4234 - „Indus y 4.0 in au oma ion and cybe ne ics” inancially suppo ed by he In e nal science und o B no Uni e si y o Technology. REFERENCES Amann, M.-Ch., Bosch, T., Lescu e, M., Myllylä, R. and Rioux, M. (2001). Lase Ranging: A C i ical Re iew o Unusual Techniques o Dis ance Measu emen . Op ical Enginee ing, Vol. 40(1), pp. 10-19. Be aldin, J.-A., Blais, F., Cou noye , L., Godin, G., Rioux, M. and Taylo , J. (2003). Ac i e 3D Sensing. In: The e- Way in o he Fou Dimensions o Cul u al He i age Cong ess. Vienna, Aus ia. Be ko ic, G. and Sha i , E. (2012). Op ical me hods o dis ance and displacemen measu emen s. Ad ances in Op ics and Pho onics, Vol. 4, Issue 4, pp. 441-471. Geng, J. (2011). S uc u ed-ligh 3D su ace imaging: a u o ial. Ad ances in Op ics and Pho onics, Vol. 3, Issue 2, pp. 128-160. Kalo á, I. and Lisz wan, M. (2005). Ac i e T iangula ion Technique. In: 5 h In e na ional Con e ence o PhD S uden s, pp. 99-104. Uni e si y o Miskolc, Miskolc. Kalo á, I. and Lisz wan, M. (2006). Indus ial Applica ions o T iangula ion Technique. IFAC P oceedings Volumes, Vol. 39(21), pp. 258-263. Schwa e, R., Heinol, H., Buxbaum, B., Ringbeck, T., Xu, Z. and Ha mann, K. (1999). P inciples o Th ee- Dimensional Imaging Techniques. In: Handbook o Compu e Vision and Applica ions, Vol. 1, pp. 463-484. Academic P ess, San Diego.