Subtle Anamorphic Lens Effects
Real-time Rendering of Physically Based Optical Effect in Theory and Practice
SIGGRAPH 2015 Course

Masaki Kawase
Silicon Studio, Corp.
masa@siliconstudio.co.jp

Anamorphic Lens
• To implement wide vision using the standard film format– Project wide image onto the sensor with horizontal compression– When screening, the image is stretched horizontally-1

Original scene

Compressed image

Screen2

Anamorphic Lens Effects• Well-known effects– Horizontal lens flare and ghosts (streaks)– Oval aperture bokeh• Less-known effects– Horizontally stretched lens flare– Horizontally stretched film grain– Anamorphic astigmatism– CA of horizontal magnification– Cylindrical lens distortion– Vignetting by oval aperture– And more …

Panasonic LA7200 Anamorphic Lens Flare by Andrei Jikh
http://vimeo.com/9493224#at=0

Anamorphic Lens Shots - Before & After
http://vimeo.com/16350276

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Importance of Less-known Effects• Helpful to create distinctive atmosphere– Each effect on its own is subtle– But together, they will affect the overall atmosphere4

Standard Lens Simulation5

Anamorphic Lens Simulation (with Well-known Effects)

6Anamorphic Lens Simulation (Adding Less-known Effects)*Exaggerated for presentation purposes7

Horizontally StretchedLens Flare and Film Grain

Horizontally Stretched Flare and Film Grain• The effects are stretched by anamorphic projector lens
• Implementation– Shrink working buffer width for the flare• Render flare normally• The results become stretched automatically– Scale the noise texcoord horizontally for the grain

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Standard Lens Flare10

Anamorphic Lens FlareEntire lens flare and film grain is stretched horizontally11

Film Grain is also StretchedStandard lensAnamorphic lensExaggerated for presentation
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Anamorphic Astigmatism

Because of Cylindrical Lenses• Anamorphic lens systems include cylindrical lenses• Astigmatism for anamorphic lens can be caused– Similar to corneal astigmatism
Including cylindrical lenses

Horizontal Focus P1

Vertical Focus P2

Anamorphic lens system
14Linear Blur by Astigmatism• Horizontal or vertical focus generates linear blur
• Never focus perfectly– Circle of least confusion
Compromised Focus P3Including cylindrical lenses

Horizontal Focus P1

Vertical Focus P2

Vertical blur at P1
Horizontal blur at P2

Anamorphic lens system

Circle of Least Confusion at P3
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Vertical Focus• Horizontal blur as back bokeh in this lensFrom real anamorphic lens16

Circle of Least Confusion Position• Cannot focus perfectly

From real anamorphic lens17Horizontal Focus• Vertical blur as front bokeh in this lensFrom real anamorphic lens18Vertical Focus
Horizontal blur as back bokeh in this lens

Circle of Least Confusion
Cannot focus perfectly

Horizontal Focus
Vertical blur as front bokeh in this lens

Implementation of Astigmatism• Offset the horizontal and vertical focal planes in opposite
directions by a little amount• Calculate horizontal and vertical CoCs separately

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Result: Vertical Focus• Horizontal blur as back bokeh

Implementation results

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Result: Circle of Least Confusion• Cannot focus perfectly

Implementation results

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Result: Horizontal Focus• Vertical blur as front bokeh

Implementation results

25Vertical Focus
Horizontal blur

Circle of Least Confusion
Cannot focus perfectlyHorizontal Focus
Vertical blurAberrations by Cylindrical Lenses

CA of Magnification• Optical Magnification ‘M’ differs by wavelength30

CA of Magnification (cont’d)31

CA of Horizontal Magnification• Apply CA of magnification only in horizontal direction

CA of magnification

CA of horizontal magnification
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Anamorphic Lens

Anamorphic Lens

CA of horizontal magnification

Standard Lens

Cylindrical Lens Distortion
Horizontally strong barrel distortion

Anamorphic lens

Standard Lens Distortion
Barrel distortion

Standard lensConclusion

Conclusion• Anamorphic lenses yield various effects– Well-known and less-known effects• Less-known effects should not be ignored– Each effect on its own is subtle– But together, they will affect the overall atmosphere39

Standard Lens

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Anamorphic Lens (with Well-known Effects)

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Anamorphic Lens Simulation (Adding Less-known Effects)*Exaggerated for presentation purposes42References••

Kawase, M. “Camera, Optics Theory and Post Effects for Renderists.” Computer Entertainment Developers
Conference, 2007.
Kawase, M. “Practical Implementation of Cinematic Lens Effects.” Computer Entertainment Developers
Conference, 2012.

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