Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens †...
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![Page 1: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/1.jpg)
Real-Time, All-Frequency Shadows in Dynamic Scenes
Thomas Annen* Zhao Dong* Tom Mertens†
Philippe Bekaert† Hans-Peter Seidel* Jan Kautz‡
*MPI InformatikGermany
†Hasselt UniversitytUL - IBBT, EDM, Belgium
‡University College LondonUK
Some materials are get from the author and this paper is presented by CG, Huang
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Outline• Introduction• Relate work• Convolution• Generation of Area Lights for Environment
Maps• Limitations• Result
![Page 3: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/3.jpg)
Outline• Introduction• Relate work• Convolution• Generation of Area Lights for Environment
Maps• Limitations• Result
![Page 4: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/4.jpg)
Introduction• Enable real-time, all-frequency shadows in
dynamic scenes.• Support area light as well as wnviroment
lighting.• The key contribution is renderng plausible soft
shadow.• Enviroment-lit scenes can be rendered.
![Page 5: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/5.jpg)
Outline• Introduction• Relate work• Convolution• Generation of Area Lights for Environment
Maps• Limitations• Result
1. Soft Shadows2. Convolution3. Precomputation and Simplification4. Environment map sampling
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Soft shadows• Early work on shadow mapping extensions
image-based rendering to average hard shadow.[Chen and Williams 93; Agrawala et al. 00]
• Classic shadow volumn method was extended to soft shadows.[Assarsson and Akenine-Moller 03]
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Convolution• Soler and Sillion[98] propose an image-based
shadow algorithm based on convolution.• Don’t support self-shadowing.
• Variance shadow maps[Donnelly and Lauritzen 06]
• Convolution shadow maps[Annen et al. 07]
![Page 8: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/8.jpg)
Precomputation and simplification• PRT [Sloan et al. 02] calculate and stroes an
illumination-invariant transport solution off-line and uses it for real-time relighting.• Challenging to support fully dynamic scenes with
arbitrary illumination.
![Page 9: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/9.jpg)
Environment map sampling• Agarwal et al.[03] proposed an efficient point
sampling strategy for environment maps.• Arbree et al. Use disk-shaped light sources to
approximation.• This paper approximate an environment with
a collection of square light sources.
![Page 10: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/10.jpg)
Outline• Introduction• Relate work• Convolution• Generation of Area Lights for Environment
Maps• Limitations• Result
![Page 11: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/11.jpg)
c
L
Convolution shadow map• x R3
• p R2 • P = T(x)• Shadow function:s(x):=f(d(x),z(p))
• Binary result:– 1 if d(x)<=z(p)– 0 else
x
p
d(x)
z(p)
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Shadow test function: s(x)• What kind of
function is s(x)?
• Heaviside Step Function: H(t)
Sha
dow
ter
m f
or x’c
L
x
p d(x’)z(p)
x’
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• Approximate shadow test with Fourier series
Convolution shadow map
)(tH c1 +c2 +..+c4 +..+c8 +..+c16
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Convolution shadow map
• Step function becomes sum of weighted sin()
• Series is separable!
)sin()cos()cos()sin()sin( zdzdzd
)(tH c1 +c2 +..+c4 +..+c8 +..+c16
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Convolution• Bulid on convolution-based methods.• Simulate penumbrae by filtering shadows
depending on the configuration of blocker, receiver, and light source.
![Page 16: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/16.jpg)
CSM order reduction• Annen et al[07] using a Fourier series to
construct the f, but it’s prone to some artifacts and shadows at contact points may too bright.
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Outline• Introduction• Relate work• Convolution• Generation of Area Lights for Environment
Maps• Limitations• Result
![Page 18: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/18.jpg)
Generation of Area Lights for Environment Maps
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Outline• Introduction• Relate work• Convolution• Illumination with Soft Shadows• Limitations• Result
1. Ringing Suppression2. Textured light sources
![Page 20: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/20.jpg)
Outline• Introduction• Relate work• Convolution• Generation of Area Lights for Environment
Maps• Limitations• Result• Conclusions and Future work
1. DirectX 102. Dual-Core AMD 2.2GHz3. NVIDIA GeForce 8800 GTX graphics card
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Result
• Buddha scene with 70k face
MM: MipmapsSAT: Summed area table
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Result
![Page 23: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/23.jpg)
Result
• Performance of this paper and image quality depend on:– choice of prefilter– Number of area lights– Shadow map size
![Page 24: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/24.jpg)
Result
• Demonstrate the effect of the sharpening function G().
![Page 25: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/25.jpg)
Result
• Shows the influence of the number of light sources used for approximating the environment map.
![Page 26: Real-Time, All-Frequency Shadows in Dynamic Scenes Thomas Annen * Zhao Dong * Tom Mertens † Philippe Bekaert † Hans-Peter Seidel * Jan Kautz ‡ *MPI Informatik.](https://reader030.fdocuments.net/reader030/viewer/2022032703/56649d2d5503460f94a049dc/html5/thumbnails/26.jpg)
Outline• Introduction• Relate work• Convolution• Generation of Area Lights for Environment Maps
• Limitations• Result• Conclusions and Future work
1. Based on convolution.2. Fast enough to render many area light sources simul- taneously.3. Provide plausible results, even though they are not
entirely physically correct.4. At future work, intend to explore the use area lights for
indirect illumination.