Recipes fo Optical Effect System Design IIReal-time Rendering of Physically Based Optical Effects in Theory and Practice

Yoshiharu Gotandatri-Ace, Inc.

Real Lens Structure• Useful to achieve photo-realistic

(physically based) optical effects– Implementation for

• Optical vignetting• Focus breathing• Bokeh with aberrations and distortions• Lens ghosts

Physical Limitations• Lens structure also gives us limitations for

lens parameters– Focus distance– F-number– Zoom

Lens Database• Lens database is useful for both

implementations and parameter limitations– The limitations prevent setting incorrect

camera parameters• Too small F-numbers (e.g. F0.x)• Too close focus distance with a big format sensor

Lens Database• Our lens database

approximates a lot of parameters

struct LensParameter{

string szName[64];u8 nAppertureAngleNumber;

f32 fDesignedFilmSize;

f32 fMinFStop;f32 fMaxFStop;f32 fFStopZoom;

f32 fMinFocusDepth;

f32 fMinProjectionDistance;f32 fMaxProjectionDistance;

//// // ----------------- Vignetting Distance// || --------------- <----------->// || ---------------- |// || || | || |// Entrance || Open Ap ||Vignetting|| |// Size || Size ||Size || |// || || | || |// || ---------------- |// || --------------- <-Frange Back ->// ----------------- ^Iris// <- Iris Distance ->// <------------ Entrance Distance ------------>//

f32 fEntranceDistance;f32 fEntranceSize;f32 fApertureDistance;f32 fOpenApertureSize;f32 fVignettingDistance;f32 fVignettingSize;f32 fFrangeBack;f32 fNaturalVignettingPower;f32 fFocusingZoomAjustiveRateWIDE;f32 fFocusingZoomAjustiveRateTELE;

u8 nFocalLengths;u8 nApertures;f32 afFocalLength[5];f32 afAperture[5];f32 afVignettingEV[5][5];

};

Lens Database• Our lens database has

a lot of lenses– This table shows some

lenses which the database includes

Lens Database ExamplesKanon EF24mm F1.4L USM

Kanon EF300mm F2.8L IS USM

Kanon EF24-70mm F2.8L USM

Kanon EF100mm F2.8 macro

Kanon EF28-300mm F3.5-5.6L IS USMAskaNP EF28-300mm F2.0

AskaNP EF14-1200mm F1.4

AskaNP EF8-2400mm F1.0

Real Lenses?• Are these lenses

unrealistic?– If there are,

• Very expensive• Very heavy and big

Lens Database ExamplesKanon EF24mm F1.4L USM

Kanon EF300mm F2.8L IS USM

Kanon EF24-70mm F2.8L USM

Kanon EF100mm F2.8 macro

Kanon EF28-300mm F3.5-5.6L IS USMAskaNP EF28-300mm F2.0

AskaNP EF14-1200mm F1.4

AskaNP EF8-2400mm F1.0

Unrealistic Lenses• Real lenses (for 35mm format) are

sometimes not easy to use– Artists may feel that it is too costly to pick up

an appropriate lens for a scene• It is a similar situation to a real lens

interchangeable camera!

Unrealistic Lenses• Lens database is still required to

implement physically based optical effects– Virtual lenses– Usability vs. physical plausibility

Virtual LensesLens Database ExamplesKanon EF24mm F1.4L USM

Kanon EF300mm F2.8L IS USM

Kanon EF24-70mm F2.8L USM

Kanon EF100mm F2.8 macro

Kanon EF28-300mm F3.5-5.6L IS USMAskaNP EF28-300mm F2.0

AskaNP EF14-1200mm F1.4

AskaNP EF8-2400mm F1.0

Still realistic

Less realistic, more useful

Awesome!I want this!

Lens configuration (parameter limitations) also follows this reality rule

Conclusion• Lens database is useful for both

implementation and parameter limitations– Physically plausible implementation for optical

effects– To prevent setting strange parameters– Real lenses are sometimes too inconvenient

Acknowledgements• Masaki Kawase• Masanori Kakimoto• Kristian Spoerer