THE AFFINE PROJECTION MODEL AS A TOOL FOR RAPID GEO-CODING OF IRS-P5 SATELLITE IMAGERY

Transcription

1 he Intenational Achive of the Photogammet, Remote Sening and Spatial Infomation Science. Vol. XXXVII. Pat B. Beijing 28 HE AFFINE PROJECION MODEL AS A OOL FOR RAPID GEO-CODING OF IRS-P5 SAELLIE IMAGERY F. Dada Javan a *, A. Azizi b a Dept. of Geomatic Engineeing, Facult of Engineeing, Univeit of ehan, Ian - fdadajavan@ut.ac.i b Cente of Ecellence fo Diate Management, Dept. of Geomatic Engineeing, College of Engineeing, Univeit of ehan, Ian - aazizi@ut.ac.i KEY WORDS: High Reolution, Puhboom, IRS-P5, Mapping, Seno Modeling, Rational Function Model, D affine tanfomation, Hazad ABSRAC: Nowada, the infomation content of the atellite imageie a a mean fo the diate foecating and management ha attacted the woldwide attention moe than befoe. On the othe hand, linea aa atellite image uch a Spot, Ikono, QuickBid, IRS, etc., with thei fleibilit in acquiing teeo coveage ove an pat of the globe, have poven to be an ecellent eplacement fo the othe pace-bone imaging tem uch a digital fame camea o whikboom technologie. he fit tep fo uing uch data i Geocoding. High eolution data inceae the need fo highe accuac data modeling. Up to now diffeent model with diffeent accuac have been dicued. hee model ae divided into two main goup of the o called igoou and non-igoou model. he igoou appoache ae the mot accuate but need cucial data uch a atellite ephemei and inne oientation paamete which ae not alwa available. he non-igoou model uch a ational polnomial, DL o D affine tanfomation on the othe hand ae le accuate but enjo the advantage of being independent fom the auilia infomation. In line with eveal othe eeach wok alead pefomed b othe eeache, thi pape et it main goal to compae the imple D affine model, a a eplacement tanfomation fo the moe ophiticated ational function appoach. he adopted tateg i baed on geneating vitual gound contol point uing ational polnomial inteection b mean of available RPC. he geneated vitual GCP povide a eliable data fo etimating the degee of fitne of the D affine model to the ational polnomial tanfomation. hi pape epot the eult of the tet conducted on a high eolution teeo IRS-P5 atellite image. Othe elated iue including diffeent method fo etimating initial value needed fo the olution of the ational polnomial inteection, uch a DL, D affine and tuncated ational polnomial ae alo peented and dicued. 1. INRODUCION Afte the ecent unami and eathquake diate with thei devatating effect, the infomation content of the linea aa atellite imageie a a mean fo the diate foecating and management ha gained much moe impotance than befoe. One of the cucial pelimina tage afte an natual diate i the apid mapping of the damaged aea uing atellite imageie. hi poce entail a geat deal of computation and field wok which hinde the apid epone to the pelimina mapping demand. wo main appoache ae ued fo geocoding of linea aa imageie. he fit appoach i the o called igoou model. hi appoach i baed on the phical modeling of the linea aa motion and attitude vaiation. Howeve, thi Method ma not be appopiate fo apid mapping ince it equie necea obital infomation a well a the eno calibation paamete which ma not be acceible. he econd appoach ue the ational polnomial model (RFM) a a eplacement fo the igoou method. Again, the RFM coefficient ae included in the metadata and ma not be acceible in all cicumtance. he olution of the RFM alo equie the egulaization and nomalization. he RFM inteection i olved iteativel and hence demanding initial value fo the object coodinate. Moeove, the olution ma undego computational collape fo a given dataet. hee complication make thee appoache non-optimal fo apid mapping application. aking into account the fact that high eolution atellite image inevitabl have lage focal length, it can be een immediatel that thee imageie enjo a ve naow field of view. he ve mall camea field of view make the incoming ignal almot paallel. hi paticula geomet povide a imple linea-paallel elationhip between the image pace and the object pace and make a imple eight paamete affine tanfomation optimum fo geo efeencing application. Simplicit of the fomulation (i.e. onl eight affine paamete fo the entie cene), few numbe of equied GCP and the achieved accuac make thi appoach ve attactive fom the apid mapping point of view. Nevethele, in pactice eveal unpedicted facto m influence the accuac of the tanfomation. One of the majo influential facto in thi epect i the teain elief undulation. hi appoach ha been alead evaluated b diffeent eeache woldwide and eaonabl accuate eult have been epoted uing onl few numbe of GCP (Fae et al., 2; Fae et al., 2; Yamakawa et al 2). he main tak undetaken in thi tud i to invetigate the fitne accuac of the D affine model with the RFM, a fa a the teain independent cenaio i concened. he adopted tateg fo the evaluation of the pelimina eult i baed on the geneation of a netwok of the o called vitual GCP whoe coodinate ae obtained b the available RPC. Few numbe of well ditibuted vitual GCP eve a the efeence data to detemine the tanfomation paamete of the D affine tanfomation and the et of the vitual gound point ae conideed a check point fo the evaluation of the abolute accuac. All accuac figue ae peented fo the check point in the object pace. hi tateg fo the accuac evaluation adopt the accuac of the vitual gound point geneated b the RPC a a citeion fo the evaluation of the fitne accuac of the affine model. In the ection that follow the baic concept of the RFM and the D affine model ae eviewed fit. hi i then followed b the eview of the fomulation of the RFM inteection. he 117

2 he Intenational Achive of the Photogammet, Remote Sening and Spatial Infomation Science. Vol. XXXVII. Pat B. Beijing 28 lat ection deal with the evaluation of the fitne accuac obtained on the teeo IRS-P5 image acquied ove a tet ite. 1.1 Rational Function Model he concept of RFM wa developed b Ge (Sadeghian, 21).hi model poject the D object pace coodinate into a 2D image coodinate and could be ued fo an tpe of image; aibone o pace bone. he Rational Function Model i epeed a a atio of two polnomial: 1 2 Whee:, ae the nomalized image coodinate X, Y, Z ae the nomalized object coodinate F i i the ode polnomial i the ode of polnomial which i uuall equal to o the ational model would be the atio of two cubic polnomial and each polnomial ha 2 tem making a total of 8 paamete which i educed to 78: i.e. (1) eain independent cenaio: When the igoou eno model i available, the RFC can be detemined via D object gid with coeponding image point which ae detemined though igoou model. In thi cae, the olution i actuall teain independent ince no teain infomation i ued (ao C V, Hu Y, 21. he method ha thee main tep: Fit, detemination of a gid of ufficient image point, Second, et up a D gid of object point via igoou model, in thi tep, igoou paamete -which ae meaued uing onboad GPS eceive and go-ae ued to compute the coeponding object coodinate of image point. hid, RFM fitting, the RPC ae computed uing image coodinate and thei coeponding object coodinate b appling pace eection he Bia Compenated RPC: Eteio oientation paamete which compie poition and attitude ae ued to calculate RPC in teain independent mode. On-boad GPS eceive detemine the atellite ephemei. Sta tacke and go detemine attitude a a function of time. Ephemei and attitude have finite accuac, about one mete fo ephemei and one o two ac-econd fo attitude [. A a eult, the calculated 8 ] RPC in teain independent mode have bia. Man eeach wok have alead been conducted a egad the method and the accuac of the bia emoval. It ha been demontated that the bia can be compenated via one hift paamete in line diection and one hift paamete in ample diection (Dial & Godecki 22). ( 1 ZXY... Y X ).( aa1... a19) ( 1 ZXY... Y X ).( 1 b1b 2... b19) ( 1 ZXY... Y X ).( cc1... c19) ( 1 ZXY... Y X ).( 1 d1d2... d19) (2) A + B () In ode to inceae the tabilit of equation, it i eential to nomalize the two image coodinate and thee object coodinate uing hift and cale paamete to fit the ange -1 ~ +1. he nomalizing equation can be decibed a:, X X Y Y Z Z X, Y, Z X Y Whee:, ae hift value fo image coodinate, ae the cale value fo image coodinate X, Y, Z ae hift value fo object coodinate X, Y, Z ae the cale value fo object coodinate he unknown paamete involved in RFM can be detemined with o without uing the igoou eno model. heefoe two computational cenaio ae peent, teain dependent and teain independent (Godecki et al., 2). Z () he bia compenated RPC can be computed a: ( ) ( ) + ( ) F X, Y, Z a b A a b A. X ( ) a b A. Z 2 2 ( ) ( ) + ( ) ( ) 2 2 F X, Y, Z c d B c d B. X c d B. Z he accuac of thi model ha been epoted le then.5 piel (Hanle & Fae, 2). Paamete fo dift can alo be added. 1.2 D Affine anfomation Affine model i a linea tanfomation which map the D object pace into 2D image pace though 8 paamete, a hown in equation (5): (5) eain dependent cenaio: When thee i no igoou eno model at hand, one ha to meaue contol point and check point fom both image and the actual DEM o map. In thi cae, the olution i heavil dependent on the actual teain elief, numbe of contol point and ditibution of contol point (ao C V, Hu Y, 21). AX + AY + AZ + A 1 2 A X + AY + A Z + A Whee A A affine paamete 1,..., 8 8 (5) 118

3 he Intenational Achive of the Photogammet, Remote Sening and Spatial Infomation Science. Vol. XXXVII. Pat B. Beijing 28 Equation 5 account fo two tanlation, thee otation and non unifom caling and kew ditotion within image pace. It could be egaded a a fit ode ational function with the denominato equal to one. Stictl peaking, the imaging geomet of a atellite puh boom canne can be decibed a pepective in the line of the linea aa and paallel in the along-tack diection. Howeve, with a ve naow field of view, the aumption that the pojection i paallel tand tue in pactical cae (Fae &. Yamakawa, 2). 1. DL Model Diect linea tanfomation, which i a fit ode ational function, map D object pace into 2D image pace via 11 paamete: Whee λ λ, ϕ ϕ, h h λ ϕ h X Y Z Becaue of nonlineait of the equation, appling the alo eie epanion give (Godecki et al., 2). ( ϕ, λ h ) dw z z w + p p( ϕ, λ h ) dw z z w + he deivation can be calculated though ome patial deivation a follow (Godecki et al., 2): (8) L X + LY + L Z + L 1 2 LX + LY + L Z L X + LY + L Z + L LX + LY + L Z Whee L,..., L DL paamete 1 11 (6) u v w u v w p p u v w u v w (9) DL paamete can be computed diectl uing EOP and IOP paamete o indiectl uing GCP. hi model i conideed a an appoimate model fo linea aa canne ince the EOP paamete ae not the ame fo all image line (Mogan, 2). 2. VIRUAL GCP GENERAION A eplained befoe, fitne accuac of the D affine model a compaed with the RFM model i evaluated b geneating vitual GCP. hee point ae calculated via the RPC acceible in the IRS-P5 metadata. hi i eplained in the ection that follow. Whee: u X Y Z XY XZ YZ X Y Z XYZ [1,,,,,,,,,,, X, XY, XZ, X Y, Y, YZ, X Z, Y Z, Z [ ], [ λϕ,, ] v X Y Z w h o evaluate the object pace coodinate of a point we hould meaue the image coodinate in at leat a teeo image. In thi olution we ue two teeo fowad and aftewad image. he equation would ead a follow (Godecki et al., 2). ] 2.1 RFM Inteection he ational function model which i peented a equation (1) i alwa efeed to a fowad RPC model which povide a mapping fom geogaphic coodinate of object image coodinate ( ϕλ,,h ) ( S, L ). Denomalizing equation (1) ield: to F F F ( ϕ, λ, h) F F F p ( ϕ, λ, h) A A A ( ϕ, λ, h) A A A p ( ϕ, λ, h) (1) 1 2 ( ϕ λ ) ( ϕ, λ, h), p,, h (7) he final obevation equation follow with (Godecki et al., 2). A. dw L (11) Whee: 119

4 he Intenational Achive of the Photogammet, Remote Sening and Spatial Infomation Science. Vol. XXXVII. Pat B. Beijing 28 F F F h w F p F F p h A w, dw [ dλ, dϕ, dh], L A A A h w A p A A p h w ( ϕ, λ ) ( ϕ, λ ) ( ϕ, λ ) ( ϕ, λ ).1 Data Set. EXPERIMENAL RESUL A teeo othokit image of the IRS-P5 atellite image ove the cit of Aak, Ian which wee acquied in 27, ae ued in the tet. he RPC paamete wee available fo both fowad and aftewad image. Figue 1 how pat of the teeo dataet ued in the poject. he unknown object pace coodinate i olved fo iteativel. At the fit iteation, the initial value fo coodinate i needed which could be detemined though linea equation uch a D affine o DL. Altenativel, tuncated RPC can alo be ued. At each iteation tep, application of leat quae, eult in coection of appoimate value of object coodinate, i.e.: ( ) 1 dw A A A L (12) Figue1. Aftewad (left) and fowad (ight) image of teeo dataet. w w + dw i i Affine Inteection (1) Fo evaluating the object pace coodinate uing affine tanfomation, one hould calculate it 8 paamete of each image at fit b appling at leat fou GCP: A mentioned befoe, fo the olution of Equation 1 appoimate abject coodinate ae equied. he image coodinate of 18 vitual GCP ae meaued. hee method ae implemented to geneate the appoimate coodinate, namel: D affine, DL and tuncated RPC. he achieved eult fo RPC inteection b appling diffeent method fo evaluating the initial value have been peented in able1. [ A,..., A ] 1 8 X, Y, Z,,,,,, X, Y, Z F F F F F A, A, A A 1 2 F F F X F F A, A, A A 8. Y A A A A A A, A, A A 1 2 Z A A A A A A, A, A A (1) Afte evaluation of the paamete, b meauing image coodinate of an point in a teeo image, it object coodinate could be detemined via the following elation: (15) Iteative leat quae olution of Equation 1 ield the object coodinate fo the vitual GCP. hi tep i then followed b the olution of Equation 1 though which D affine paamete ae deived uing an combination of the well ditibuted vitual GCP. Subequentl, fo an vitual GCP whoe can and line coodinate i alead meaued, new object coodinate can be detemined via Equation 15. he final fitting accuac evaluation i then pefomed b compaing the object coodinate of the GCP calculated b Equation 1 and the object coodinate computed b Equation 15. Net ection peent the eult of the tet conducted on IRS-P5 teeo image. Method E(m) N(m) h(m) Iteation D affine DL uncated RPC able2. Reult of RPC inteection, appling diffeent method fo evaluating initial value. A the able 1 indicate, all method of deiving appoimate value have poduced eaonabl accuate initial value and the equation have been uccefull conveged. It i inteeting to note that the affine model fo calculating appoimate value ha lead to malle numbe of iteation in the olution of Equation 1. hi implie that the affine model geneate moe accuate eult a compaed to the othe two appoache. Ditibution of the geneated vitual GCP i peented in Figue 2. Having detemined the object coodinate of the vitual GCP, in the net tep the D affined paamete (Equation1) ae olved to deive the 8 affine paamete b appling diffeent numbe of GCP and CP. hi i followed b the olution of Equation 15 to deive the object coodinate of all vitual GCP. he eidual vecto fo the height and planimetic coodinate when 5 GCP wee ued ae peented in Figue and epectivel. 12

5 he Intenational Achive of the Photogammet, Remote Sening and Spatial Infomation Science. Vol. XXXVII. Pat B. Beijing 28 REFERENCES Dial, Gene and Jacek Godecki 22. Block Adjutment with Rational Polnomial Camea Model. Poceeding of ASPRS 22 Confeence, Wahington, DC, Apil 22-26, 22. Fae. C.S., and. Yamakawa, 2, Applicabilit of the Affine Model fo IKONOS Image Oientation ove Mountainou eain. In Poc. of ISPRS-EARSeL Joint Wok on High Reolution Mapping fom Space, Hannove, on CDROM. Figue2. Ditibution of geneated vitual GCP Fae, C.S. &. Yamakawa, 2. Inight into the affine model fo atellite eno oientation. ISPRS Jounal of Photogammet and Remote Sening Godecki. J., Dial. G., Lute, J., 2. Mathematical Model Fo D Featue Etaction Fom Multiple Satellite Image Decibed B RPC. ASPRS Annual Confeence Poceeding, Ma 2. Hanle, H.B. and Fae, C.S., 2. Seno Oientation fo High-Reolution Satellite Image: Futhe Inight into Bia- Compenated RPC. Intenational Achive of the Photogammet, Remote Sening and Spatial Infomation Science, 5(B1): Figue. the eidual vecto of planimetic coodinate. Mogan, M., 2, Epipola Reampling of Linea Aa Scanne Scene, PhD Dietation, Depatment of Geomatic Engineeing, Univeit of Calga, Canada. Okamoto, A., Fae, C., Hattoi, S., Haegawa, H., Ono,., An altenative appoach to the tiangulation of SPO image. Intenational Achive of Photogammet and Remote Sening2 (B), Yamakawa., Fae C.S., 2, he affine pojection model fo eno oientation: epeience with high-eolution atellite image, IAPRS of 2th Conge, Commiion I, WG V/5, Itanbul (CD). ao C V, Hu Y, 21.he Rational Function Model: a tool fo poceing high-eolution image. Eath Obevation Magazine, 1(1):1-16. Figue. the eidual vecto of D object coodinate. A the Figue indicate and accoding to able, the X and Y eidual ae quite mall impling accuate plannimeic fitting potential of the D affine model. Howeve, the height eidual do not indicate high fitting accuac. hi how that a fa a the height value ae concened, thee i a non-lineait in the image data that the linea tem of the D affine cannot take it into account. Howeve, anothe eaon fo the lowe height fitting accuac ma be the meauement eo duing the homologou point identification and meauement tage. CONCLUDING REMARKS Savopol, F., Amenaki, C., Modelling of the IRS-1C atellite pan image uing the DL appoach. Intenational Achive of Photogammet and Remote Sening, Vol. 2, Pat, pp Sadeghian, S., M. J. Valadan Zoej, M. R. Delava, A. Abootalebi, 21. Peciion Rectification of High Reolution Satellite Image Without Ephemei Data, Intenational Jounal of Applied Eath Obevation and Geoinfomation (JAG), (): Wang, Y., Automated iangulation of Linea Scanne Image, Joint Wokhop of ISPRS WG I/1, I/ and IV/, Seno and Mapping fom Space, Hanove, Septembe, 27-. he oveall eult achieved in thi tud futhe uppot the concluion aived b othe eeache a egad the applicabilit of the D affine tanfomation a a eplacement model fo the moe ophiticated RFM. hi tatement i tue unde the povio that the tip length doe not eceed the ize of a high eolution atellite fame. 121

6 he Intenational Achive of the Photogammet, Remote Sening and Spatial Infomation Science. Vol. XXXVII. Pat B. Beijing 28 No. GCP(CP) (1) 5(1) 6(12) X(m) Y(m) Z(m) X(m) Y(m) Z(m) X(m) Y(m) Z(m) able. Reult of affine inteection. No.GCP(CP) X(m) Y(m) Z(m) (1) (1) (12) able. otal RMSE fo affine inteection. 122