Making Your Bokeh Fascinating - Real-time Rendering of Physically Based Optical Effect in Theory and Practice - SIGGRAPH 2015 Course
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The document discusses creating realistic bokeh effects through a method involving a pencil map and light ray simulations, focusing on aberration types and lens parameters. It details optimization techniques for rendering efficiency and flexibility in artistic aperture shapes using Look-Up Tables (LUTs). The conclusion emphasizes the potential for photorealistic bokeh generation using these techniques.
![Introduction
• Basic idea and theory [Kawase08]
– Only circular aperture
• Practical implementation and optimization [Kawase12]
– Any kind of aperture shapes
2](https://image.slidesharecdn.com/06makingyourbokehfascinatings2015kawaseen-150824030410-lva1-app6891/85/Making-Your-Bokeh-Fascinating-Real-time-Rendering-of-Physically-Based-Optical-Effect-in-Theory-and-Practice-SIGGRAPH-2015-Course-2-320.jpg)
![References
• [Kawase08] Kawase, M. “Bokeh Expressions Based on Optics.” Computer Entertainment Developers
Conference, 2008.
• [Kawase12] Kawase, M. “Practical Implementation of Cinematic Lens Effects.” Computer
Entertainment Developers Conference, 2012.
• Kawase, M. “Reduce Artifacts Generated by Mipmapped Buffers.” Computer Entertainment Developers
Conference, 2009.
• Trávník, J. “On Bokeh.” Jakub Trávník's resources. http://jtra.cz/stuff/essays/bokeh/index.html
• 安藤幸司 『光と光の記録「レンズ編」』 AnfoWorld http://www.anfoworld.com/LensMF.html
• 吉田正太郎（1997）『カメラマンのための写真レンズの科学』地人書館.
63](https://image.slidesharecdn.com/06makingyourbokehfascinatings2015kawaseen-150824030410-lva1-app6891/85/Making-Your-Bokeh-Fascinating-Real-time-Rendering-of-Physically-Based-Optical-Effect-in-Theory-and-Practice-SIGGRAPH-2015-Course-63-320.jpg)
Making Your Bokeh Fascinating - Real-time Rendering of Physically Based Optical Effect in Theory and Practice - SIGGRAPH 2015 Course
- 1. Making Your Bokeh Fascinating Real-time Rendering of Physically Based Optical Effect in Theory and Practice SIGGRAPH 2015 Course Masaki Kawase Silicon Studio, Corp. masa@siliconstudio.co.jp
- 2. Introduction • Basic idea and theory [Kawase08] – Only circular aperture • Practical implementation and optimization [Kawase12] – Any kind of aperture shapes 2
- 3. Contents • Creating the Pencil Map • Creating the Bundle-of-Light-Ray Map (Pencil Map) – “Bundle of Light Rays” or “Pencil Rays” (referred to as “Pencil” here onwards) • Application to Arbitrary Aperture Shapes • Scattering or Gathering? • Results • Conclusion 3
- 4. Creating the Pencil Map
- 5. Creating the Pencil Map • Precompute light paths from the aberration diagram – Takes spherical and axial chromatic aberrations into account Light paths make up pencil map (small number of rays) Longitudinal aberration diagram Pencil map Amount of aberration Incidentheight 5
- 6. Circular Bokeh Rendering • V coordinate represents the distance from the optical axis – Mapping each slice to a circle produces a circular ‘bokeh’ Pencil map Circular bokeh U: Distance from lens V:Distancefrom opticalaxis 6
- 7. Discretized Result… 7 • Chromatic aberration is an issue • Three wavelengths (R/G/B) are insufficient to represent the dispersion
- 8. Increasing Wavelength Samplings • Calculate the map with more wavelengths • Convert into the RGB space 8
- 11. Bokeh with Spherical and Chromatic Aberration • Imperfect focus • Front bokeh with red sharp edge • Back bokeh with blue soft edge 11 Zoomed-in view around the focal point
- 12. Comparison with photographs Captured in real photographs Generated from pencil map 12
- 13. Creating the Pencil Map of Doublet 13 • Calculate the map with the longitudinal aberration diagram • Using actual lens parameters (if they exist) – Only ray paths of each wavelength are required Light paths make up pencil map Longitudinal aberration diagram Pencil map
- 14. Pencil Map of Doublet Pencil maps and bokeh Zoomed-in view around the focal point 14
- 15. Comparison with photographs 15 • Typical correction – Front bokeh has soft purple edge and the center is darker – Back bokeh has sharp green edge and the center is brighter Front bokeh in photographs Back bokeh in photographs Front and back Bokeh with Pencil map
- 16. Different Type of Doublet • Residual chromatic aberration is more visible than residual spherical aberration Light paths make up pencil map Longitudinal aberration diagram Pencil map 16
- 17. Pencil Map of Doublet (Different Type) Zoomed-in view around the focal point Pencil maps and bokeh 17
- 18. Pencil Map of Doublet (Previous Type) Pencil maps and bokeh Zoomed-in view around the focal point 18
- 19. Comparison with photographs Front bokeh in photographs Back bokeh in photographs Front and back Bokeh with Pencil map 19
- 20. Optimization of Pencil Map • Wasteful parts in the texture – Sparse, many texels are empty – There is not enough precision around the more important ‘focusing’ texels Wasteful pencil map 20
- 21. Optimization of Pencil Map (cont’d) • Normalizing height of bundle at every distance(u-axis) by the maximum height(bokeh size) • Less empty texels, and great improvement in precision around focusing texels Wasteful pencil map Normalized pencil map 21
- 22. Spherical lens (with no corrections) Aspherical lens (chromatic aberration is not corrected) Achromatic doublet lens 22
- 23. Achromatic doublet lens (different type) Apochromatic (APO) lens Perfect lens (does not actually exist) 23
- 24. Application to Arbitrary Aperture Shapes
- 25. Various Aperture Shapes • Aperture shape is an important artistic factor – Typically 5~9 diaphragm blades – Changes from rounded to n-gon • How to map pencil onto the polygonal aperture shape? – 3D Textures? • Too large, not practical ? Pencil map Aperture shape 25
- 26. Indirect Reference of Pencil Map • Precompute an LUT texture that stores V coordinates of pencil map LUT texture 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 V Vertical slice 26
- 27. Indirect Reference of Pencil Map (cont’d) • Sample pencil map indirectly at run-time Pencil map 0 1 V Look up Sampling LUT 27
- 28. Indirect Reference of Pencil Map (cont’d) • LUT determines the aperture shape – Independent of pencil map – Can reproduce curved shapes of a diaphragm blade • Prepare a set of LUTs for various diaphragm conditions – Other shapes such as stars, hearts, … can be used 28
- 29. Various LUTs • For the number of diaphragm blades and opening levels • Smooth deformation is possible by interpolating between two adjacent LUTs 4 blades 5 blades 6 blades 7 blades Fully opened ClosedClosing 29
- 30. Silhouette LUTs for debug Fully opened 4 blades 5 blades 6 blades 7 blades ClosedClosing 30
- 32. Both can be Implemented • Better quality by scattering – Heavy processing load • Hybrid method is recommended – Both scattering and gathering 32
- 33. Hybrid Method • To determine which pixels will be scattered or gathered, use: – The CoC size – Difference in luminance between neighboring pixels Original Result (green: gathering pixels) 33
- 34. 34 Gathering
- 35. 35 Hybrid of Scattering and Gathering
- 36. Optimization • Use a half resolution buffer for scattering – Scattering process can be 16x faster • Split the process into several passes with hierarchical resolution buffers – Use lower resolution for larger bokeh – The process at the 1/4 x 1/4 resolution can be 256x faster • Scatter a pixel every 2x2 pixels for relatively larger bokeh in each resolution – Pixels that have an especially heavy processing load will be 4x faster 36
- 37. Results
- 38. Back bokeh with cyan fringes Front bokeh with red/purple fringes Bokeh Simulation in Real Time
- 43. Curved Diaphragm and Optical Vignetting • Opening / Closing – Deformation • Circular aperture • Polygonal aperture – Rotation – Optical Vignetting • Cat’s Eye Effect 43
- 44. 5-blade Circular Aperture (with Optical Vignetting) f/1.4 (Fully Opened)
- 45. 5-blade Circular Aperture (with Optical Vignetting) f/2 (1 Stop Closed)
- 46. 5-blade Circular Aperture (with Less Optical Vignetting) f/2.8 (2 Stops Closed)
- 47. 5-blade Circular Aperture (with No Optical Vignetting) f/5.6 (4 Stops Closed)
- 48. 5-blade Circular Aperture (with Fake Diffraction Spikes) f/11 (6 Stops Closed)
- 49. Various Aberrations and Corrections • Correction of SA and axial CA mostly affect bokeh Focus plane Back bokeh Front bokeh Differences between front and back bokeh 49
- 50. 50 Spherical Lens (with No Corrections)
- 51. 51 Aspherical Lens (with Chromatic Aberrations) Correction of Spherical Aberration
- 52. 52 Achromatic Lens Corrected for Red and Blue Wavelengths
- 53. 53 Achromatic Lens (Different Type) Corrected for Red and Blue Wavelengths
- 54. 54 APO (Apochromatic) Lens Corrected for 3 Wavelengths (More Expensive Lens)
- 55. 55 Almost Perfect Lens Without any Spherical and Longitudinal Chromatic Aberrations
- 56. 56 STF (Smooth Transition Focus) Lens Soft Edged Bokeh by Apodization Optical Element Radial gradient ND filter
- 57. Residual Aberration Visibility Out of focus: Large Aberrations: Less visible Out of focus: Small Aberrations: Strongly Visible
- 58. Residual Aberration Visibility Out of focus: Large Aberrations: Less visible Out of focus: Small Aberrations: Strongly Visible Out of focus: Large Aberrations: Less visible Out of focus: Small Aberrations: Strongly Visible
- 59. Comparison with Photographs (Achromat) Real photographs with achromatic lensReal-time simulation results 59
- 60. Comparison with Photographs (APO) Real photographs with apochromatic lensReal-time simulation results 60
- 61. Conclusion
- 62. Conclusion • Reproduce photorealistic bokeh with pencil map and LUT – Pencil map defines bokeh characteristics – LUT defines bokeh shapes • Optimization – Various options available – Combinations can be used to improve performance 62
- 63. References • [Kawase08] Kawase, M. “Bokeh Expressions Based on Optics.” Computer Entertainment Developers Conference, 2008. • [Kawase12] Kawase, M. “Practical Implementation of Cinematic Lens Effects.” Computer Entertainment Developers Conference, 2012. • Kawase, M. “Reduce Artifacts Generated by Mipmapped Buffers.” Computer Entertainment Developers Conference, 2009. • Trávník, J. “On Bokeh.” Jakub Trávník's resources. http://jtra.cz/stuff/essays/bokeh/index.html • 安藤幸司 『光と光の記録「レンズ編」』 AnfoWorld http://www.anfoworld.com/LensMF.html • 吉田正太郎（1997）『カメラマンのための写真レンズの科学』地人書館. 63