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![Page 1: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/1.jpg)
Real-Time Relighting
Digital Image SynthesisYung-Yu Chuang1/10/2008
with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan
![Page 2: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/2.jpg)
Realistic rendering
• We have talked about photorealistic rendering for complex materials, complex geometry and complex lighting. They are realistic but slow.
![Page 3: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/3.jpg)
Real-time rendering
• Its goal is to achieve interactive rendering with reasonable quality. It’s important in many applications such as games, visualization, computer-aided design, …
![Page 4: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/4.jpg)
Real-Time relighting
• Lighting is the process of adjusting lights. It is an important but time-consuming step in animation production pipeline.
• Relighting algorithms for two kinds of lights– Distant environment lights– Near-field lights for production
![Page 5: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/5.jpg)
Relighting algorithms for distant environment lights
![Page 6: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/6.jpg)
Natural illumination
People perceive materials more easily under natural illumination than simplified illumination.
Images courtesy Ron Dror and Ted Adelson
![Page 7: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/7.jpg)
Natural illumination
Rendering with natural illumination is more expensive compared to using simplified illumination
directional source natural illumination
![Page 8: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/8.jpg)
Reflection maps
Blinn and Newell, 1976
![Page 9: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/9.jpg)
Environment maps
Miller and Hoffman, 1984
![Page 10: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/10.jpg)
HDR lighting
![Page 11: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/11.jpg)
Examples of complex environment light
![Page 12: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/12.jpg)
Examples of complex environment light
![Page 13: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/13.jpg)
Direct lighting with complex illumination
)ωp,( ooL )ω,p( oeL
iiiio ωθcos)ωp,()ω,ωp,(2
dLf is
)ωp,( oB iiiio ωθcos)ωp,()ω,ωp,(2
dLf ds)ω( opB iiiiω, ωθcos)ω()ω(
2 odLf ds p
p q
![Page 14: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/14.jpg)
Function approximation
• G(x): the function to approximate• B1(x), B2(x), … Bn(x): basis functions• We want
• Storing a finite number of coefficients ci gives an approximation of G(x)
)()(1
xBcxG i
n
ii
![Page 15: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/15.jpg)
Function approximation• How to find coefficients ci?
– Minimize an error measure• What error measure?
– L2 error
• Coefficients
2])()([
2 I i
iiL xBcxGE
X
iii dxxBxGBGc )()(
![Page 16: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/16.jpg)
• Basis Functions are pieces of signal that can be used to produce approximations to a function
1c
2c
3c
Function approximation
![Page 17: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/17.jpg)
• We can then use these coefficients to reconstruct an approximation to the original signal
1c
2c
3c
Function approximation
![Page 18: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/18.jpg)
• We can then use these coefficients to reconstruct an approximation to the original signal
xBcN
iii
1
Function approximation
![Page 19: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/19.jpg)
Orthogonal basis functions
• Orthogonal Basis Functions– These are families of functions with special
properties
– Intuitively, it’s like functions don’t overlap each other’s footprint• A bit like the way a Fourier transform breaks
a functions into component sine waves
ji
jidxxBxB ji 0
1
![Page 20: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/20.jpg)
Integral of product
iiij
i jiji
i jjjii
GFdxgfdxxBxBgf
dxxBgxBfdxxGxF
ˆˆ)()(
)()(
dxxGxFI
i
ii xBfxF )( j
jj xBgxG )(
)ω( opB iiiiω, ωθcos)ω()ω(2 o
dLf ds p
![Page 21: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/21.jpg)
Basis functions
• Transform data to a space in which we can capture the essence of the data better
• Spherical harmonics, similar to Fourier transform in spherical domain, is used in PRT.
![Page 22: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/22.jpg)
Real spherical harmonics
• A system of signed, orthogonal functions over the sphere
• Represented in spherical coordinates by the function
where l is the band and m is the index within the band
0
0
0
,cos
,cossin2
,coscos2
,00 m
m
m
PK
PmK
PmK
y
ll
ml
ml
ml
ml
ml
![Page 23: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/23.jpg)
Real spherical harmonics
![Page 24: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/24.jpg)
Reading SH diagrams
–+
Not thisdirection
Thisdirection
![Page 25: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/25.jpg)
Reading SH diagrams
–+
Not thisdirection
Thisdirection
![Page 26: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/26.jpg)
The SH functions
00y
11y
11y
12y
22y
02y
12y2
2y
![Page 27: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/27.jpg)
The SH functions
![Page 28: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/28.jpg)
Spherical harmonics
![Page 29: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/29.jpg)
Spherical harmonics
-1-2 0 1 2
0
1
2
( , )lmY
xy z
xy yz 23 1z zx 2 2x y
1
m
l
![Page 30: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/30.jpg)
SH projection
• First we define a strict order for SH functions
• Project a spherical function into a vector ofSH coefficients
S
ii dssysfc
mlli 1
![Page 31: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/31.jpg)
SH reconstruction
• To reconstruct the approximation to a function
• We truncate the infinite series of SH functions to give a low frequency approximation
2
0
~ N
iii sycsf
![Page 32: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/32.jpg)
Examples of reconstruction
![Page 33: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/33.jpg)
An example
• Take a function comprised of two area light sources– SH project them into 4 bands = 16 coefficients
2380042508370317000106420
27800417009400908093006790
3291
.,,.,.,.,.,.,.,,.,,.
,.,.,.,.
![Page 34: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/34.jpg)
Low frequency light source
• We reconstruct the signal– Using only these coefficients to find a low frequency
approximation to the original light source
![Page 35: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/35.jpg)
Harr wavelets• Scaling functions (Vj)
• Wavelet functions (Wj)
• The set of scaling functions and wavelet functions forms an orthogonal basis
![Page 36: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/36.jpg)
Harr wavelets
![Page 37: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/37.jpg)
Example for wavelet transform
• Delta functions, f=(9,7,3,5) in V2
![Page 38: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/38.jpg)
Wavelet transform
• V1, W1
![Page 39: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/39.jpg)
Example for wavelet transform
• V0, W0 , W1
![Page 40: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/40.jpg)
Example for wavelet transform
![Page 41: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/41.jpg)
Quadratic B–spline scaling and wavelets
![Page 42: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/42.jpg)
2D Harr wavelets
![Page 43: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/43.jpg)
Example for 2D Harr wavelets
![Page 44: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/44.jpg)
Applications
19%5% L2
1%15% L2
3%10% L2
![Page 45: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/45.jpg)
Relighting algorithms for animation production
![Page 46: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/46.jpg)
Relighting for production
• Lighting is a time-consuming process.• Artists adjust lighting parameters and wait for
a couple of hours or days to get feedback.• Local shading with complex scene and many li
ghts• Interactive relighting
– Interative visual eedback– Fixed scene and camera– Lower quality – Scalable with sene complexity and number of light
s
![Page 47: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/47.jpg)
Deep framebuffer• Gershbein and Hanrahan, SIGGRAPH 2000
![Page 48: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/48.jpg)
Deep framebuffer
![Page 49: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/49.jpg)
Deep framebuffer
![Page 50: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/50.jpg)
LPICS
• Pixar, SIGGRPH 2005. A practical realization for the deep framebuffer approach on GPUs
LPICS0.1s
Final renderer2,000s
video
![Page 51: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/51.jpg)
Lightspeed• ILM, SIGGRAPH 2007• An even more practical system with automatic
shader conversion. (2.7s v.s. 57m)
![Page 52: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/52.jpg)
Direct-to-indirect transfer
• Hasan et. al. SIGGRAPH 2006• Deep framebuffer approaches only support loc
al shading, but not indirect lighting
direct lighting With indirect lighting
![Page 53: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/53.jpg)
Concept
• Distribute gather samples on scene surfaces
![Page 54: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/54.jpg)
Concept
• Direct illumination on both gather samples and view samples
![Page 55: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/55.jpg)
Concept
• Inter-reflections between gather samples
![Page 56: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/56.jpg)
Concept
• Final gather on view samples
![Page 57: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/57.jpg)
Inter-reflections between gather samples
gather sample
gather sample
![Page 58: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/58.jpg)
Inter-reflections between gather samples• Assume all gather samples are diffuse
![Page 59: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/59.jpg)
Inter-reflections between gather samples
![Page 60: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/60.jpg)
Inter-reflections between gather samples
![Page 61: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/61.jpg)
Final gathering
![Page 62: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/62.jpg)
Direct on gather
Indirect on view
Final
Transfer
matrix
Direct on view
Concept
![Page 63: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/63.jpg)
Scene: Still Life
Precomputation: 1.6 hours
11.4 – 18.7 fps Polygon: 107k
![Page 64: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/64.jpg)
Scene: Temple
Precomputation: 2.5 hours
8.5 – 25.8 fps Polygon: 2M
![Page 65: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/65.jpg)
Scene: Hair Ball
Precomputation: 2.9 hours
9.7 – 24.7 fpsPolygon: 320k
![Page 66: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/66.jpg)
Scene: Sponza Atrium
Precomputation: 1.5 hours
13.7 – 24.9 fps Polygon: 66k
![Page 67: Real-Time Relighting Digital Image Synthesis Yung-Yu Chuang 1/10/2008 with slides by Ravi Ramamoorthi, Robin Green and Milos Hasan.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f035503460f94c172aa/html5/thumbnails/67.jpg)
Comparison
DTI: 8-25 fps (2.5 hr precomputation)
Monte Carlo path tracer: 32 hours