materi komputer grafik
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ComputerGraphicsInf4/MSc
Computer Graphics
Lecture Notes #16
Image-Based Lighting
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ComputerGraphicsInf4/MSc
1/11/!"" !
G$o%a$ I$$umination and Image-
Based Lighting& 'raditiona$ Computer Graphics in(o$(es)
* Mode$$ing +ith matter) geometr, +ith ref$ectance
properties& Image-Based Lighting a$$o+s)
* Com%ination of rea$ and s,nthetic graphics +ith
consistent i$$umination. using images as $ight sources
* 0tension of n(ironment mapping
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ComputerGraphicsInf4/MSc
n(ironment Mapping
& Computing the co$or according to theref$ection (ector
& No se$f-shado+ing. no inter-ref$ection
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ComputerGraphicsInf4/MSc
1/11/!"" 4
Image Based Lighting
& dd mode$s or o%2ects to scenes and a$$o+
them to %e manipu$ated in the scenes
& Mode$$ing +ith $ight a$$o+s added o%2ects
to %e i$$uminated consistent +ith image
e0istent $ighting - photorea$istic inc$usions
& 3e start +ith the ans+er %, finding the
scene i$$umination
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ComputerGraphicsInf4/MSc
1/11/!""
Image Based Lighting
& 5ea$ Scene
& Goa$) p$ace s,nthetic o%2ects on ta%$e
a$$ pictures 7 8e%e(ec 9:-99;
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0tracting scene $ighting
& Capture i$$umination using i$$umination
sphere
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Image Based Lighting
5ea$ scene
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ComputerGraphicsInf4/MSc
1/11/!"" :
Image Based Lightingcaptured i$$umination fie$d
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1/11/!"" 9
Image Based Lighting
5ea$ scene
$ight %ased mode$
$oca$ scene
s,nthetic o%2ects
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1/11/!"" 1"
Image Based Lighting
&
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Image Based Lighting
& 5ender into the scene
%ac=ground
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ComputerGraphicsInf4/MSc
1/11/!"" 1!
Image Based Lighting
& 5ender s,nthetic o%2ects
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Image Based Lighting& ffect of $oca$ scene on rea$ scene
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Image Based Lighting
& dd differences to image
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Some more resu$ts
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Light 7ro%e Images
& Spherica$ n(ironment Maps
& In most digita$ images. pi0e$ (a$uesaren>t proportiona$ to the $ight $e(e$sin the scene* $ight $e(e$s are encoded non$inear$, so the,
appear either more correct$, or more p$easing$,on C5's
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ComputerGraphicsInf4/MSc High-Dynamic Range
Photography& Standard digita$ images t,pica$$, represent
on$, a sma$$ fraction of the d,namic range?
the ratio %et+een the dimmest and %rightestregions accurate$, represented?present inmost rea$+or$d $ighting en(ironments
& 'he %right $ight saturates the pi0e$ co$our
& Need a high d,namic range image +hich can%e produced %, com%ining images ofdifferent shutter speed
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ComputerGraphicsInf4/MSc
High-Dynamic Range
Photography
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@85 images
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ComputerGraphicsInf4/MSc
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ComputerGraphicsInf4/MSc Comparison: Radiance map
versus single image
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,es Aor 5e$ighting
& 0tracting en(ironment maps from e,es for use inintegrating and re$ighting scenes
& pp$, IBL to the 8 o%2ects added into the image
& http)//+++,outu%ecom/+atch(M$$'SofDt:
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ComputerGraphicsInf4/MSc
Shape from Shading
& E%taining the 8 shape from an image
& ssuming Lam%ertian ref$ection
& Can reco(er the norma$ (ector if +e cast the$ight from different directions
zzyyxx nLnLnL ++== nL
L
nL, ;cos6
Object
N
L
Example: sphere(lit from left)
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ComputerGraphicsInf4/MSc
& Integrate the norma$so(er the surface to
compute the 8 surface& 3e can a$so estimate
the co$our informationand use this for te0ture
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ComputerGraphicsInf4/MSc
Surface inserted into ne+ scenes& $it according to the g$o%a$ i$$umination of that scene
& 'his i$$umination can of course come from e,esF
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ComputerGraphicsInf4/MSc
cuiring the 5ef$ectance Aie$d of a@uman Aace
& Simu$ating ref$ectance on human faces
reuires a $ot of effort and computation*Need to acuire the ref$ectance mode$*Su%surface scattering
& Instead of simu$ating the g$o%a$
i$$umination. +e can simp$, i$$uminate theface %, rea$-$ights from different directions& Creating images of ar%itrar, $ight
conditions %, com%ining the captured data
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ComputerGraphicsInf4/MSc
The Light Stage:6-seconde!posure
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Light Stage 8ataErigina$
5eso$ution)
64!
Lighting through image recom%ination) @ae%er$i H9!. Nimeroff H94. 3ong H9
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ComputerGraphicsInf4/MSc
5ef$ectance Aunctions
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Lighting 5ef$ectance Aunctions
normalized
light map
reflectance
function
lighting
product
rendered
pixel
1
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ComputerGraphicsInf4/MSc
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5eferences
& Rendering Synthetic "#$ects into Real
Scenes. SIGG57@ 9:
& %c&uiring the Re'lectance (ield o' aHuman (ace, S)**R%PH +
http:.de#evec.org
& ,es Aor 5e$ighting. Nishino SIGG57@!""4
http://www.debevec.org/http://www.debevec.org/
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