materi komputer grafik

7/25/2019 materi komputer grafik

1/31

ComputerGraphicsInf4/MSc

Computer Graphics

Lecture Notes #16

Image-Based Lighting


2/31


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


3/31


n(ironment Mapping

& Computing the co$or according to theref$ection (ector

& No se$f-shado+ing. no inter-ref$ection


4/31


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


5/31


1/11/!""


& 5ea$ Scene

& Goa$) p$ace s,nthetic o%2ects on ta%$e

a$$ pictures 7 8e%e(ec 9:-99;


6/31


1/11/!"" 6

0tracting scene $ighting

& Capture i$$umination using i$$umination

sphere


7/31


1/11/!""


5ea$ scene


8/31


1/11/!"" :

Image Based Lightingcaptured i$$umination fie$d


9/31


1/11/!"" 9


5ea$ scene

$ight %ased mode$

$oca$ scene

s,nthetic o%2ects


10/31


1/11/!"" 1"


&


11/31


1/11/!"" 11


& 5ender into the scene

%ac=ground


12/31


1/11/!"" 1!


& 5ender s,nthetic o%2ects


13/31


1/11/!"" 1

Image Based Lighting& ffect of $oca$ scene on rea$ scene


14/31


1/11/!"" 14


& dd differences to image


15/31


Some more resu$ts


16/31


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


17/31

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


18/31


High-Dynamic Range

Photography


19/31


@85 images


20/31



21/31

ComputerGraphicsInf4/MSc Comparison: Radiance map

versus single image


22/31


,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:


23/31


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)


24/31


& 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


25/31


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


26/31


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


27/31


The Light Stage:6-seconde!posure


28/31


Light Stage 8ataErigina$

5eso$ution)

64!

Lighting through image recom%ination) @ae%er$i H9!. Nimeroff H94. 3ong H9


29/31


5ef$ectance Aunctions


30/31


Lighting 5ef$ectance Aunctions

normalized

light map

reflectance

function

lighting

product

rendered

pixel

1


31/31


1/11/!"" 1

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/

Documents

materi komputer grafik