Geoetrc Correcton or Georeferencng
GEOREFERENCING: fro ge to p Coordntes on erth: (λ, φ) ge: (, ) p: (, ) rel nteger Trnsfortons (nvolvng deforton): erth-to-ge: χ erth-to-p: ψ (crtogrphc proecton) ge-to-p: ψ (χ 1 ) p-to-ge: χ (ψ 1 ) χ (, ) Note ψ s lws known (crtogrphc proecton) χ hs to e eprcll estted (λ,φ) ψ (, ) A. Derns, L. Bg
IMAGE TO MAP TRANSFORMATION I J MAP TO IMAGE TRANSFORMATION Y X The center of n ge pel hvng ge nteger coordntes (I, J) s trnsfored nto p pont wth rel (not nteger) coordntes (, ) whch do not correspond to p pel The center of p pel hvng p nteger coordntes (X, Y) s trnsfored nto n ge pont wth rel (not nteger) coordntes (, ) whch do not correspond to n ge pel The p pel (X,Y) tkes vlue fro the vlues of the pels round the pont (, ) RESAMPLING We need ths! Mp to ge trnsforton for ge to p regstrton A. Derns, L. Bg
Deternton of the MAP to IMAGE Trnsforton () Adopton of pretrzed trnsforton odel = f ( X, Y,,, K, ) 1 2 = f ( X, Y,,, K, ) 1 2 () Identfcton of ge ponts wth known p coordntes (control ponts) (, ) ( X, Y ), k= 1,2,..., n k k k k (c) Lest-squres deternton of trnsforton preters k = f ( X k,y k, 1, 2,, ) (v ) k k = f ( X k,y k, 1, 2,, ) (v ) k k (v ) k 2 (v ) k 2 = n â 1, ˆ 1,â 2,..., ˆ (d) Applcton of trnsforton to ll p pels fllng n the ge re = f ( X, Y, ˆ, ˆ, K, ˆ ) 1 2 = f ( X, Y, ˆ, ˆ, K, ˆ ) 1 2 1 X R 1 Y C (= p rows) (= p coluns) A. Derns, L. Bg
Trnsforton odels = = 2 02 11 2 20 01 10 00 ), (, 0 1 1 1, 1 1,1 0,! = = 2 02 11 2 20 01 10 00 ), (, 0 1 1 1, 1 1,1 0,! Polnol odel = t t s θ θ θ θ cos sn sn cos Rototrnslton wth scle fctor A. Derns, L. Bg
Resplng I 1 I J 1 J J 1 J 2 Assgn vlue to p pel (X, Y) pped nto ge pont (, ) fro the vlues of the neghorng ge pels I 1 I 2 Use onl ths efore clssfcton I, J Nerest Neghor Resplng: Mp pel tkes vlue of closest ge pel I, J1,,,, I 1, J I 1, J1 A. Derns, L. Bg
Blner Resplng = 0 1 or Bcuc Resplng = 0 1 2 2 3 3 A. Derns, L. Bg
Georeferencng Eple: An ge-to-p regstrton of the orgnl ge ove wth UTM grd on the regstered ge elow lck res (vlue 0 = no dt code) correspond to p pels fllng outsde the ge re A. Derns, L. Bg
Ige-to-ge Regstrton Regstered ge Nerest neghor Detl Regstered ge Bcuc Detl Orgnl ge - SPOT 1998 (nd 3) Trget ge - TM 1996 (nd 3) Note soothng effect A. Derns, L. Bg
Prctcl suggestons nd defnton Pln terrn: splest odels & less ponts Rough terrn: cople odels & ore ponts LR ges: lck odels HR ges: gr / rgorous odels Hoogeneousl dstruted ponts wth known coordntes n oth ge / p Ground control ponts: used to estte the trnsfortons Check ponts: used to vldte the results
Hgh resoluton stellte orne ges: geoetrc dstorsons Erth rotton effect Pel deforton t the order Erth curvture Atospherc refrcton Polnols re not suffcent to regster hgh resoluton ges Algorths fro photogretr re dpted Collnert equtons re ppled, wth ttenton to ntrnsc proles of stellte orne dgtl ges. Blck odels (Rtonl Polnol Functons) Gr odels (RPF Rtonl Polnol Coeffcents) Rgorous odels (Phscll sed)
Dt Levels Iges cn e processed t dfferent levels nose reovl tospherc effects reovl (rdoetrc regstrton) georeferencng lck / gr / rgorous odels (geoetrc regstrton) orthorectfcton derved p producton Iges provders specf the s Dt levels
Eple: DgtlGloes Dt Levels 0 Reconstructed, unprocessed nstruent nd plod dt t full resoluton, wth n nd ll counctons rtfcts (e. g., snchronzton fres, counctons heders, duplcte dt) reoved. 1 Reconstructed, unprocessed nstruent dt t full resoluton, tereferenced, nd nnotted wth ncllr nforton, ncludng rdoetrc nd geoetrc clrton coeffcents nd georeferencng preters (e. g., pltfor epheers) coputed nd ppended ut not ppled to the Level 0 dt (or f ppled, n nner tht level 0 s full recoverle fro level 1 dt). 1 Level 1 dt tht hve een processed to sensor unts (e. g., rdr cksctter cross secton, rghtness teperture, etc.); not ll nstruents hve Level 1 dt; level 0 dt s not recoverle fro level 1 dt.
Eple: DgtlGloes Dt Levels 2 Derved geophscl vrles (e. g., ocen wve heght, sol osture, ce concentrton) t the se resoluton nd locton s Level 1 source dt. 3 Vrles pped on unfor spcete grd scles, usull wth soe copleteness nd consstenc (e. g., ssng ponts nterpolted, coplete regons oscked together fro ultple orts, etc.). 4 Model output or results fro nlses of lower level dt (. e., vrles tht were not esured the nstruents ut nsted re derved fro these esureents).