Cameras. Importance of camera models

Transcription

1 pture imges mesuring devie Digitl mers mers fill in memor ith olor-smple informtion D hrge-oupled Devie insted of film film lso hs finite resolution grininess depends on speed IS sie 35mm IMAX et Importne of mer models Understnding mers llos: Using photogrphs of rel orld for modeling nd rendering Rendering 3D senes hih is euivlent to tking pitures of the virtul orld

2 lnr pinhole mer model inhole lso lled enter of projetion point of onvergene of ll inoming rs 3 lnr pinhole mer model Imge plne plne here interseting inoming rs rete the olor smples piels of the imge defined non-prllel vetors nd u v 4

3 lnr pinhole mer model oint nd vetors define generl plnr pinhole mer 5 Speil pinhole mer model K to ssume tht vetors nd re perpendiulr sure piels nd sme length projets in the enter of the imge plne 6 3

4 4 7 onstrutor Hflot hfov int int h hfov is the horiontl field of vie [degrees] is the idth of the imge [piels] h is the height of the imge [piels] / tn hfov h 8 rojetion of points u v [ ] v u v u v u v u v u 0 0 < 0 no projetion > 0 vlid projetion

5 lipping left of vie frustum test u < 0 ove vie frustum test v < 0 ehind suvolume right of vie frustum test u > idth test < 0 elo of vie frustum test v > height 9 iel oordintes iel u v hs enter t.5fflotu.5fflotv The imge strethes from 0.0f to flot nd from 0.0f to floth A ro hs piels: piel 0 - A olumn hs h piels: piel 0 h- An imge point uf vf uf nd vf re flots elongs to piel int uf int vf 0 5

6 ther mer methods Aess Get vie diretion fol length Get r piel enter Get horiontl / vertil field of vie Get prinipl point piel oordintes of projetion onto imge plne Nvigtion Trnsltion left-right up-don forrd-krd Rottion left-right pn up-don tilt pith sides roll Revolve horiontll round point thet degrees Revolve vertill round point thet degrees ositioning le mer suh tht it looks t point from distne d nd hs up vetor up Internl prmeters hnge Zoom in-out hnge of field of vie hnge of resolution ropping/etensions Vie interpoltion Give H 0 nd H rete N mers tht smoothl hnge the vie from H 0 to H Aess Get vie diretion vd.unitvetor Get fol length f vd* Get r for piel u v -- integers ru v *u0.5f*v0.5f Get r for piel imge point uf vf -- flots ruf vf *uf *vf Get piel enter -- integers u v ru v Get horiontl field of vie hfov *tn/*.length/f // ssumes projets t / Get prinipl point imge oordintes of projetion u -*.UnitVetor/.Length v -*.UnitVetor/.Length 6

7 7 3 Trnsltions step UnitVetor krd forrd step UnitVetor don up step UnitVetor right left *. *. *. Trnsltion right 4 Rottions : :... θ θ θ θ θ RotteAout Roll RotteAout Tilt RotteAout RotteAout RotteAout n n

8 mer positioning le mer suh tht it looks t point from distne d hs vie diretion vd nd up is vetor in the vertil plne of the mer // ssumptions: retngulr piels up nd vd re normlied vd*d vd up.unitvetor*.length vd.unitvetor*.length u * v * vd*f up vd d 5 Zooming Fol length hnges: f f * oom - u * v * vd*f _ f _ f 6 8

9 More or feer piels; *k h h*k nd do not hnge *k nd h hnge uffers hve to e relloted hnge of resolution 7 ropping/etensions Set the imge to retngle u 0 v 0 u v u 0 * v 0 * u -u 0 h v -v 0 u 0 v 0 u v 8 9

10 Vie interpoltion Given H 0 nd H rete N intermedite mers Assumption: H 0 nd H hve the sme internl prmeters i 0-0 *floti/flotn- vd i vd 0 vd -vd 0 *floti/flotn- i 0-0 *floti/flotn- See mer positioning 9 Rel orld mer models Aperture is finite depth of field onl ojets t ertin distne re in fous Lens distortion stright lines re urved in the imge rrel pinushion 0 0

11 Thin lenses rs through lens enter do not hnge diretion rs prllel to optil is go through fol point F nl ojets t ertin depth re in fous Depth of field imge F F perture ojet