render fotorealista
TRANSCRIPT
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Beteckning:________________
DepartmentofMathematics,NaturalandComputerScience
PhotorealisticRenderingwithVray
AnjaRackwitz
MarkusSterner
15June2007
Thesis,10points,Clevel
ComputerScience
CreativeProgrammingSupervisor/Examiner:SharonALazenby
Coexaminer:Juliahln
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ACKNOWLEDGEMENTS
First,wewouldliketothankMagooasthecompanyfortakingusinundertheirwingsas interns. It has been a great and very educational experience for both of us and
withoutthatexperiencenoneofthisworkwouldbeviable.Wewerealsoassignedagreatthesisontheiraccountandlendingusbothknowledgeandequipmenttorealize
thisresearchproject.
Notonly
were
we
able
to
use
their
facilities,
we
also
joined
the
CEO
of
Magoo,
Anders,
on a trip to lmhult to visit the IKEA design studio. This leads us to our other greatsupport, Bengt Larsson, who has helped us with both the structure of the work andprovided us with a huge insight in the 3D and photography business. Other helpfulpeople at IKEA that need mentioning are Sren Larsson and Maria Forsman, whohelpeduswiththemeanstocreateourkitchenscene.Lastbutdefinitelynotleast,we
alsowould liketoextendourthankstoSharonLazenby,oursupervisorandtutorforthiscourseattheUniversityofGvleforsupportingusduringthisperiod.
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Figure1:Theoriginalphotography(1)
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TABLEOFCONTENTSAcknowledgements....................................................................................................................................... 3
1 Introduction......................................................................................................................................... 7
1.1 Hypothesis............................................................................................................................................. 7
1.2 Anticipatedproblems............................................................................................................................ 7
1.3 Expectedresults.................................................................................................................................... 8
1.4 Limitations............................................................................................................................................. 8
1.5 Method.................................................................................................................................................. 8
1.5.1 Methodofchoice.......................................................................................................................... 8
1.5.2 Methoddescription...................................................................................................................... 9
1.6 Questionsatissue.................................................................................................................................. 9
1.7
Purpose
of
the
research
........................................................................................................................
9
1.8 Targetgroup.......................................................................................................................................... 9
1.9 Earlierresearchonthesubject.............................................................................................................. 9
1.10 Dispositionofthepaper...................................................................................................................... 10
1.11 Typographicalconventions.................................................................................................................. 10
2 Theoreticalframework....................................................................................................................... 11
2.1 ColorandLightRealisminReality..................................................................................................... 11
2.1.1 TheNatureofRealLight............................................................................................................. 11
2.1.2 Howdoescoloremitfromobjects?............................................................................................ 12
2.1.3
Colormodels
striving
for
realism
.............................................................................................
13
2.1.4 ColorprofilessRGBvs.AdobeRGB.......................................................................................... 14
2.1.5 Colortemperature...................................................................................................................... 15
2.2 RenderingVirtualRealism................................................................................................................ 16
2.2.1 TheVrayRenderer..................................................................................................................... 16
2.2.2 GlobalIllumination...................................................................................................................... 16
2.2.3 AntiAliasingFilters..................................................................................................................... 18
2.2.4 BumpMapping........................................................................................................................... 20
2.2.5 DisplacementMapping............................................................................................................... 20
2.2.6 Highdynamicrangeimaging....................................................................................................... 20
3 VisualResponse.................................................................................................................................. 22
3.1 Photographyasastartingpoint.......................................................................................................... 22
3.1.1 Realism........................................................................................................................................ 22
3.1.2 Makingthepicturealivethreemainforces............................................................................. 26
3.2 PerceptionPsychology......................................................................................................................... 30
3.2.1 RelativeBrightness..................................................................................................................... 30
3.2.2 Colorinterpretation.................................................................................................................... 30
3.2.3
Shapesand
forms........................................................................................................................
31
4 Process............................................................................................................................................... 33
4.1 StudyExcursionDescription................................................................................................................ 33
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4.2 Choosingaroom.................................................................................................................................. 33
4.3 ImageAnalysis..................................................................................................................................... 34
4.3.1 Analyzingtheoriginalimage....................................................................................................... 34
4.3.2 Thingstochangeinthe3Dscene(Figure22)............................................................................. 37
4.3.3
Postproductionin
Photoshop
.....................................................................................................
40
4.4 Experiment.......................................................................................................................................... 42
Results........................................................................................................................................................ 43
4.5 Finalimage........................................................................................................................................... 43
4.5.1 Thelittlethings........................................................................................................................... 44
4.5.2 Flaws........................................................................................................................................... 44
5 Discussion.......................................................................................................................................... 45
5.1 UsefulmeanswhencreatingphotorealisticCGI.................................................................................. 45
5.2 Pro&Contraphotography.................................................................................................................. 45
5.3
Pro&
Contra
3D
...................................................................................................................................
46
5.4 Whatcouldhavebeenmadebetter,andhow?.................................................................................. 47
5.4.1 Theimage................................................................................................................................... 47
5.5 Furtherresearchonthetopic.............................................................................................................. 47
6 Conclusion.......................................................................................................................................... 48
7 References......................................................................................................................................... 49
7.1 Persons................................................................................................................................................ 50
7.2 Websites.............................................................................................................................................. 50
7.3 Reports................................................................................................................................................ 50
7.4 Books................................................................................................................................................... 51
7.5 Tableoffigures.................................................................................................................................... 52
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1 INTRODUCTION
Photorealism isonethe largestandmostcommonlyusedareas inthe fieldof3D. In
the beginning of the 21century, the Swedish furniture company IKEA started todigitallystorealloftheirproductsinalargedatabase.Inthebeginningofthisproject
alltheworkwasdonebyphotographers.However,IKEArealizedthepotentialandtheopportunitiesofthisnewgrowingmarketsimplynamed3D.Theystarted lookingfor
exceptional artists in this specific branch when they realized that their own field ofartists would not cut it. They found the company Magoo Studios this obvious step
leads
immediately
to
the
research
question.
How
does
IKEA
want
their
pictures
createdbyMagooStudiosandwhatmakestheIKEAproductstolookrealisticina3D
world? The picture will not only have to appear realistically, but also give theimpression that it was taken by a real photographer with IKEAs entire theoreticalframeworkasbackground.
Today, the pictures created with various 3D tools are not similar enough to picturestaken by a real photographer in a studio instead of in the 3D room of computer
software.Forthisprimaryreason,thisresearchisneededandveryvaluableforalotofindividualswiththesameinterest.
In this research, the main objective is to reveal the secrets of professionalphotographersandimplementtheirknowledgeoftheirtradeinto3Dsoftware.Afield
tripto
IKEAs
main
photo
studio
will
be
conducted
to
ascertain
this
information.
Most
ofthetestingwillbeaccomplishedatMagooStudiosofficetofindouthowtoreachthisgoalofaphotorealisticpictureanddevelopingaprocedurethatcanberepeatedtimeaftertimewithdifferentmodels,materialsandlights.
1.1 Hypothesis
Realism today is within the 3D creation, where not being able to tell the differencebetween two images, one made by a camera and one rendered by a 3D program.Whenyouasksomeone inthe3Dbusinesswhattheythinkwillmakeapicturemore
realistic,the
answer
is
almost
every
time:
irregularity,
dirt,
grain
or
imperfect
makes
perfect, thisconclusion isthesameoneas theonebeingbrought tothe test inthis
paper.
However,hypotheticallywebelieveitistrue.
1.2 Anticipated problems
Photography and photorealism can in many ways be a very subjective issue. This isoneproblemthatcanbecomequitelargeandtotallyunmanageable.However,inmost
cases,thisproblemwillnotoccurwhenitcomestoarealisticfeelinginanimage,but
inother
cases
it
is
not
realism
when
an
image
is
supposed
to
mediate
afeeling,
where
different viewers may have different interpretations. Otherproblems that are in thephotorealism area are the obvious problem with lighting contra material attributes.
Different materials have different attributes that work proficient with other lights,
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which leads to different lighting setups for different materials, even though it is thesamemodel.Forexample,oneverydullmetallicmaterialiscreatedinthefirstsceneA.Toachievethewantedeffectonthematerial,aFresnelvaluehasbeenintroducedwhich demands a lot more intensity on the lights. Fresnel provides a more realisticfallofftothereflections,andalsofacingtheobserverspointofview.Therefore,ifweusethesamelightsinsceneB,whereallmaterialsaremuchbrighteranddonothave
asin
this
case
aFresnel
value,
everything
will
become
too
bright.
Accordingly,
every
scenedemandsdifferentlightingattentioneventhoughithasthesamegeometry.Ofcourse,evendifferentgeometrywillrequireadifferentlightsetup.
Typically,theobservercandefinewhatdoesnotappearrealistic.Thismeansthatthehumaneyeisfamiliarwitharealisticsurrounding,anddetectsevensmalldivergences
veryeasy.Thatiswhyasyntheticphotorealisticimagehastobeveryclosetorealityinsomeareaswheretheeyeisverysensitive.
1.3 Expected results
Becauseof
the
fact
that
this
paper
has
brought
up
an
enormous
subject,
no
absolute
revealingtruthwillbedeclared,althoughhopefullysomepiecestothevastpuzzlethat
is called photorealism will be put in the right places. However, this research willsummarize certain knowledge, maybe not of a global scale, nevertheless furtherinformationtohelp3Dprofessionalswiththeireverydaywork.
1.4 Limitations
SincethisresearchwillbeconductedintheserviceofMagooStudios,itwillonlyfocuson the software that Magoo has at its disposal. The software consists of the 3D
programAutodesk
3D
Studio
Max,
which
includes
V
ray
renderer.
No
comparison
of
theVrayrenderertootherrendererssuchasmentalraywillbecarriedout,becauseitisnotintheareaoftheresearchwherephotorealismwillberesearched.However,this
paperwilldescribevariousproblemsandlimitationsofthevrayrendererforrealisticimagery.Forthatreason,thisresearchispurelyartistically,nomathematicalissuesor
similarity will be researched within this thesis, as well as there will be no animationsequenceandtroubleshootingwithavoidingflickerwithanyofthetoolsthatwewill
use.Therefore,thisresearchprojectisaimedtowardMagoo,IKEA,andtheirguidelineframework,whereonlystillimageswillbeprocessedandresearched.
1.5 Method
When our research is to reach a result that is to be interpreted by the eyes, it isdoubtfulthatonemightnotcallitartistic.Justbecauseofthatfactourresearch,asalot of other research in the computer science area, will be done in the manner of aconstructiveresearch,wheretheconclusionsarebasedonempiricalfacts.
1.5.1 Method of choice
SincethisprojectisaimedwiththelineofworkthatMagooStudiosareconducting,sowillthispaper,althoughatsomewhatwiderspan.Themainresearchwillbeascenetaken by a photograph and then that photo (Figure 1on page 4) will be mimed as
similaraspossiblewiththehelpofthe3Dsoftwareatourdisposal.Whatmightbea
problem
with
this
method
is
if
the
photograph
taken
by
the
camera
is
not
exactly
like
the way IKEA wants it, the research conducted may be heading in a very wrongdirection.
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1.5.2 Method description
The first step would be the recreation of the photographed scene with models andtextures, placing all the objects in the right places and so forth.The big challenge isthentolightthesceneinthesamewaythephotographerdid,withthegoaltoachievetheexactsamepictureattheendoranevenbetterresult.
1.6 Questions at issue
Howshouldacomputergeneratedimagebecreatedtolookphotorealistic?
Whattoolsareappropriatetousetoreachthewantedresult?
Whatarethelimitations,problems,prosandconsforbothphotographyand3D?
1.7 Purpose of the research
Intodayssociety,3Dgraphicsisarapidlygrowingmarketthatmostlyisestablishedin
television commercials, computer, console games, and special effects in movies. Araisingdemandforrealistic3Dfootagetherebyisadvancing.Thisleadsdirectlytoour
research, which is mainly created in the service of Magoo Studios, however also forindividuals who strive for a photorealistic result in the 3D graphics area. Due to thescaleofthisresearchandthehugetopicofphotorealism,wehavenarroweditdownaccordinglytothe limitationcaptions.Wewill focusonthecreationofphotorealisticfurnitureandhomescenes,whiletryingtomakethemasrealisticaspossiblewiththetimeandtoolswehaveatourdisposal.Withthistaskathandeverysuccessivestepinthe right direction will be documented. In short, we will make a home environment
and/or single furniture look attractive (a must have feeling), as well as appearing
realistic.
1.8 Target group
Basically, this paper is written as a foundation stone for people working withphotorealisticrendering.Itsummarizesideasandknowledgeaboutphotography,lightand color theory, and 3D, especially the rendering process. It can be useful foreveryonewhoisinterestedinoneofthesetopics.
1.9 Earlier research on the subject
Intodayscreationofactionandsciencefictionmoviesortelevisionseries,there isaveryexcessiveamountofcomputergenerated imagesusedforthecreationofeitherthings that are impossible to make with raw materials or scenes that would be tooexpensivetocreatewithouttheaidofcomputergeneratedimagery(CGI).Sinceevery
new effect or creation is different from the other, each one of these new effectsrequiressomeformofresearchtogetthedesiredresult.However,everytoolthat is
usedontheotherhandhasbeendevelopedbysomesortofresearcher;thereforeonemightaskthem,whatmakessomethingaresearch?Forexample,thecreationofthe
motion picture Lord of the rings directed and produced by Peter Jackson, hugearmies were moving across middle earth. How could such a scene be made without
CGI?To
hire
10,000
extras
and
coordinate
them,
would
be
an
almost
impossible
task
andthecostwouldbetremendous. Instead,astudioof3D individualswashiredand
accomplishedthattaskmostadmirably.
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Thegoalofthisresearchistomimicaphotographtakenbyarealcamera,whichonecannotruleoutthefactofallpreviousinquiriesanddiscoveriesproducedintheworldofphotography.All3Dhasphotographyinfluences.Thereforetoexcludethehistoryofphotography research would be inevitable. To dig deeper into the category ofphotographyphysicsisalwaystobefound.Becauseofthis,alotofphysicaltermsareusedintodays3Dgraphics.
The issuethathasbeenbroughtforth inthisdiscussion isthefactthatallofthishasbeenalreadycreatedonvariouslevels,butitisalsouptooneanotherwhatyouwouldcall research. Though it might be hard to believe that anyone previous has made aresearch onhow IKEAwants theirCGIsappearance. The art director at IKEA mighthave someclear ideasorhave made somedrafts of them.However, theymight not
have lookeddeeper intothesubjectofwhy theywantaparticular look, inaspecificwayorhaveacharacteristicfeel.
1.10 Disposi tion of the paper
Photorealism
in
images
can
be
seen
as
the
art
to
find
a
balance
and
harmony
betweenscientificstructuresandpureartisticwork,saysBengtLarsson.Tosuccess
withthiscombinationwesometimescallafeelingforimages,directlytranslatedfromSwedishsbildknsla(2).That iswhythisresearch isdividedwiththescientificpartabout the theoretical background, whereas the artistic side of our work will bediscussedthereafterinvisualresponse.Thepracticalwork,describedinpart3,consistsofcloningaphotoofoneofIKEAskitchenin3D(Figure1).
1.11 Typographical conventions
Manyof
the
translated
technical
words
are
taken
from
awide
ranging
dictionary
on
theInternet.(3)
Thesoftware3DStudioMaxabbreviatesto3dsMax.
Threedimensionalabbreviatesto3D.
HighdynamicrangeimagingwillbeshortedtoHDRI.
ComputergeneratedimagerytoCGI
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2 THEORETICAL FRAMEWORK
The process of creating synthetic images that are indistinguishable from realphotographs is called realistic image synthesis (4). To achieve photorealism with acomputerisachallengingtaskandrequiresunderstandingofthefundamentalphysicsandpsychophysicsof light.Howdoes light interactwithmaterialsandsurfaces inthe
realworld?Whathappenswhenlightraysenterthehumaneye?
In the 3Dworld there are many mathematical algorithms that simulate thisprocess.Light is bouncing around from a light source through the scene into the camera.
Depending
on
the
objects
materials
the
light
creates
reflections
and
refraction
on
surfacesor isscattering inamedium.Thereareseveral importanttermsandtoolsof
photorealismsuchasvray,globalillumination,raytracing,antialiasing,andsoforth.Sincetheyarekeystonesinthisresearchathoroughexaminationofthesesubjectsisinorder.
2.1 Color and Light Realism in Reality
2.1.1 The Nature of Real Light
TheGreekshavefoundedthebaseoftodayscurrenttheoriesof light.Theybelievedthat
light
was
emanating
from
the
eye
and
touching
the
objects
that
we
see.
Even
first
theoriesaboutreflectionandrefractionweredescribedby theGreekmathematicianEuclid, the astronomer Cleomedes and Ptolemy, mathematician, geographer,
astronomer, and astrologer. New breakthroughs in understanding light were merelycompleted at great distances until the 17
th century with Christian Huygens (1629
1695), a Dutch mathematician, astronomer and physicist and Isaac Newton (16421727),theregardedEnglishmathematician,physicist,astronomer,naturalphilosopherand alchemist. Many breakthroughs in mechanic, gravitation, and optic were madeespecially by Newton. However, since their findings, light was interpreted as a wavemotionandcouldbeseparatedoutintoitscolorspectrumwithaprism.Newtonalsopublishedatheorythatlightparticlesareemittedfromlightsourcesandmoveinstraitlinesuntilthey impingeonasurface.ThomasYoung(17731829)andAugustFresnel
(17881827)
studied
the
effects
of
polarization
and
diffraction.
That
gained
credence
to
thewave theoryrefinedby JamesMaxwell (18311879),whodefined the lightasanelectromagneticwave.Intheearly20
thcentury,AlbertEinsteinmodernizedthewhole
physicalworld,amongothersbyintroducingtheuseofphotonstodescribethephotoelectric effect; the process whereby electrons are liberated from a metallic material
which is rayed with electromagnetic radiation such as xray, ultraviolet light ordaylight.Thephotonistheelementaryparticleinlightexplainingtheelectromagnetic
effects.
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Today,thephysicsoflightisdefinedasacombinationofseveraldifferentmodelssuchas ray optics, wave optics, electromagnetic optics, and photon optics. In computergraphics,ray optics is the fundamentaland almostsolely model for lightcalculation.(4)(5)
Figure2:Theelectromagnetic spectrum,whichencompasses thevisible regionof lightfor the
humaneye
2.1.2 How does color emit from objects?
The process of seeing is much more complex than taking a picture with a photocamera.Thepictureon the retina in theeye is notonly thereflection of thereality.Thispictureneedstoconverttoelectricalimpulsesandtobeinterpretedbythebrain.
Light falls onto an objects surface. The light is absorbed, refracted or reflected indifferentwavelengthsfromthesurfacedependingonwhatkindofmaterialtheobjectconsistsof.Thenthiscertainwave lengthenterstheeyeandreaches theretina.Thehumaneyehasatrichromaticcolorsense,whichmeansthreedifferenttypesofcone
cellsfor
red,
green
and
blue
light
that
that
turns
the
incoming
information
to
neuronal
signals.Ifalltheformsofconesarestimulatedequally,thecoloriswhite.Blackisseen,
if none of them responds. This combination offers to apprehend the lights wavelengthsfrom400nmto780nmofthecolorspectrum(Figure2,Figure3).Forhumanbeings, this color spectrum is continuing and means that they can apprehend every
color and light, but ultraviolet and infrared light. Some animals have this ability, forexample bees. They are sensitive for ultraviolet light for everything but the redfrequencies.Thebeesseeredasgreytones.
Therefore, color can be defined as both subjective (what we see on an objects
surface),andevenobjectiveas thecertainwave lengththathasbeenreflected fromtheobjectssurface.(6)(7)
Figure3:Thisimageshowsthevisiblespectrumofwhitelight
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2.1.3 Color models striving for realism
The observers color impression is subjective. Everyone apprehends different colors.Thepresentdaylivingischaracterizedbyallthinkableformsofimagesinmedia.Thereare both printed media like papers, books, magazines, posters, catalogues, etc andnonprintedmediasuchastheweb,film,computergraphicsinvideogames,computergames,presentations,advertisingandmuchmore.Toproducephotorealistic images,
the reproduction of the original will, appear exactly the same in an ideal case. Theprocessforthemajorityofeveryreproductionforscreenorprintisdigitaltoday.This
requires technically that all equipment display the colors in the exact same way,practicallythisisnotpossible.
Thedifferencebetweenprintedornonprintedpresentsthemainproblem.Printscanonlyabsorborreflectacertainwavelength(subtractivecolormixwithcyan,magenta,yellowandblack),whilescreensofanykindareworkingwithanadaptivemixoflight
(phosphors).Theimaginationintheidealcaseisforexampleamonitorcandisplaytheequalcopyofapicturewith itscolorand intensity.Assoonas the light in theroom
changestodark,theoriginalpictureloosescontrastandintensity,whiletheimageonthescreenappearstobebrighter.Theoppositehappenswhenlightmeetsthescreen
andthe
contrast
nearly
disappears.
The
human
power
of
seeing
is
very
adaptive
and
adjustssuchvarianceincontrasts,color,intensityetc.
Even equipment working with the same technology can heavily distinguish themselves. These differences are often based on the equipment construction andfunctionality. A monitor uses phosphors to produce colors. A scanner or digital
camerashassensitive lightsensorstocapturedata.Printerscolorsaregeneratedbydifferent pigments of CMYK color model. For exampleworking with colored pictures
withascanner, a monitor, andaprinterwithoutusing the sameColor ManagementSystem(CMS) involvesgreatdiscrepanciesofcolorvalidity.Therefore,everydeviceisdelivered with its own machine profile, which has to be compatible with others,following the International Color Consortium (ICC) standard. Every machine workingwiththe imageshouldusethesamecolorprofileandeventhesamecolormodel,as
longas
possible.
With
every
conversion
from
one
gamut
to
another
(for
example
RGB
toCMYK)somecolorinformationwillbelost,becauseoftheirdifferentcoloramount.(6)
PrinterscanonlyworkwiththeCMYKcolormodel,whichissmallerthantheRGBcolormodel.Thatcreatessomeproblemsforsomecolorsarenotprintable.Theyhavetobeconverted to an equivalent CMYK color mix. It appears always some divergence,especially luminous colors. Very bright white tones or very dark black tones arecomplicatedtoprint.Thisisaboutupto34%colorinwhiteormore95%ofblack.Theprinters cannot display this minimal amount of color and a sharp edge appears.Therefore, IKEA sets a limit to 247 for white (maximum 255) and 10 for black whileworkingintheRGBmode.Thislimithastobeobservedespeciallyforborderregionstoprevent the object from floating out into the whitebackground.Smaller regions like
highlightsinreflectionsaregrantedexception.
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2.1.4 Color profiles sRGB vs. Adobe RGB
The human eye can apprehend a color spectrum as represented in the CIE xy
chromaticitydiagram(Figure4).Thisspectrumismuchlargerthananycolorprofile.AcolorwiththreeRGBvalueshasalsotobeassociatedwithacolorprofilelikesRGBor
Adobe RGB as two of the most common representatives. sRGB was created in
cooperationby
Hewlett
Packard
and
Microsoft
Cooperation
for
certain
use
on
LCD
and
CRTmonitors,digitalcameras,scannersandprinters. Ifproperlycalibrated, theycannearlyproduceallcolorsinthesRGBscolorgamut(colorspace).ThesRGBsgamutisthe smallest one and therefore limited for more demanding outputs such asprofessionalphotoprints.WorkingwithAdobeRGBoffersawidergamutespeciallyforgreen tones as shown below (Figure 4). However, due to the fact that those colorscannotbedisplayedonusualscreens,thisprofiledemandsbetterandmoreexpansiveequipment.AssigningthesRGBprofiletoan imagewiththeAdobeRGBprofilecould
result in loosing color information. (8) Rendered images, delivered by 3ds Max, areuntagged. Their color spectrum closely resembles the sRGB gamut with its color
structure.Thereforewecanhandletheminafairlypredictableway.(2)
Figure4:ThisimagesshowsthesRGBgamut(thesmall)andtheAdobeRGBgamut,bothplaced
in the CIE 1931 color space chromaticitydiagram. The outer curved boundary represents the
spectralcolors,withthelightswavelengthmeasuredinnanometers.
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2.1.5 Color temperature
Principallyeveryobjectreflectsacertainwavelength,butnottheidealizedblackbodywhich absorbs any kind of light. A light sources color temperature meters thetemperature that a black body has while lighting it with different lights. The colortemperatureismeasuredinKelvinasinsomeexamplesinthetablebelow(Table1).
CommonColorTemperatures
Source K
Candleflame 1900
Sunlight:sunsetorsunrise 2000
100watthouseholdbulb 2865
Tungsten lamp (500W 1k)
3200
Fluorescentlights 3200
7500
Tungstenlamp(2k 10k) 32753400
Sunlight: early morning,lateafternoon
4300
Sunlight:noon 5000
Daylight 5600
Overcastsky 60007000
Summer sunlight plus sky
blue
6500
Skylight 1200020000
Table1:Realworld color temperatures, startingwith the lower temperaturesgoingfrom red,
throughwhitelighttoblue.(9)
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Thelightisredifthecolortemperatureisaround2400K,yellowat4800Kandbluishat9300K.Daylightisdefinedaround6500K(Figure5).(10)
Figure5:ThecolortemperatureplacedintheCIE1931colorspacechromaticitydiagram.
Evenwhenknowingallaboutcolor,colormodelsandprofiles,colortemperature,etc,
still leaves hundreds of questions unanswered. Bengt Larsson expressed himself thisway:Formecolorseemstobeamixofvoodooandmarshyground.(2)
2.2 Rendering Virtual Realism
2.2.1 The V-ray Renderer
Vray
is
arendering
plug
in
for
the
3D
software
3D
studio
Max
which
supports
almost
every feature in 3Dstudio max. The plugin is made by a Bulgariancompany namedChaos group.Vray is an extremely powerful tool when it comes to rendering. Vrayhas large arsenal of tools to its disposal, for example ray traced reflections, indirectillumination,caustics,antialiasing,etc.Therewillbeashortdescriptionlaterofsome
of theexcellent tools that isprovidedwith thevrayplugin,whichalso involvesourresearch.(11)(12)
2.2.2 Global Illumination
Global illumination or GI is yet another tool for photo realistic images. Global
illumination is a set of algorithms that can be used in 3D, for example Ray tracing,beam tracing,ambientocclusionorphotonmapping.Allof theseGlobal illumination
methodsuse
algorithms
named
diffuse
inter
reflection
and
specular
reflection.
Diffuse
interreflectionisdescribedbylighthittinganunevensurface,bouncesoffitagainandhits other surfaces, thereby illuminating them as well. While specular reflection is a
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reflectioncomingfromaperfectevensurfacesuchasamirrororalakeonacleardayandthereforereflectstheraysinastraightangleaccordingtothelawofreflection.Thislawstatesthatanyincominglightthatbouncesoffasurfaceandisreflectedwillhavethesameangelastheincominglight.(13)
The main goal of global illumination is to enable a correct calculation of the lights
intensity
at
any
point
in
the
model.
Without
using
global
illumination
the
image
often
appearsflatandsyntheticandloosesitrealistictouch,forexamplecolorbleeding.Thecoloringofthesurfacefromthereflectionsofthespherescanbesimulatedwithglobalillumination,otherwisewithradiosityorcoloredlight(Figure6)(14).
Figure6:Arenderwithout(l)andwith(r)globalilluminationon.
Themajorityoftheglobalilluminationalgorithmsthathavebeendevelopedarebased
ontwomajortechniques:Raytracing(pointsampling)andradiosity(finiteelements).Bothofthemhavetheirstrengthsandweaknesses.Hybridtechniquesarecombining
thebest
of
both.
(4)
2.2.2.1 Ray tracing
Ray tracing is a method used mostly when creating photo realistic images. However
because of its precision and excellent quality, it also is a very demanding renderingmethod.Whattheraytracerdoesissimilartothename,whichismisleading.First,theraytracerssoftwaredeterminatesthepositionofthecamerainthescene.Secondly,itcalculatestheanglewherethecameraispointedanditsfieldofview.Afterthatphase,the ray tracing algorithm sendsouta ray for each pixel in the viewport out into thescene.Thenthesoftwarecalculatesthecolorofeachpixel,dependingontheraysentfromthecameraandbouncedonthetargetedsurfacethatithitslater.Raytracingis
thoughttobethemostaccuratemeasureofrenderingpossible.However, italsohasflaws, such as depth of field. It cannot be rendered, because with a ray tracing
algorithmeverythinggetsperfectlysharpandeven.(15)(16)
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2.2.2.2 Radiosity
Radiositytechniquesweredevelopedand introducedbyateamofresearchersattheCornellUniversityat1984;someyearsbeforetheraytracingmethodswasestablishedasanalternativemodel.Thisalternativefiniteelementmethodisaglobalilluminationalgorithm handling the interaction of light on purely diffuse surfaces. This methodsinnovation consists in objecttoobject reflections. Earlier light reflection models did
not account for the interaction of Lambertian (diffuse) surfaces and thereforeincorrectly calculated the global illumination effects. The surfaces in the scene are
divided up into smaller patches, which are rendered in turn. For each pass of thealgorithm, the total amount of light at each patch is calculated, meaning that light
bouncingoffasurfacehittinganotherisaddedaswellinthenextpass.
Laterradiositycouldhandlemorecomplexreflectionsmodels,howevernospecularorglossysurfaces.Radiosityisquiteefficientinsimplesceneswithdiffusematerials,but
itbecomes verycostly in termsof rendering timeandstorage requirementswhen itcomestocomplexmodelsandnondiffusematerials.(4)(17)
2.2.2.3 Caustics
Caustics are called the reflection patterns that appear when light is reflected on ametallic surface or refracts through transparent objects such as glass, water or ice.These patterns depend only on the light sources position as shadows, not theobserverspointofviewsimilartoreflections.Intherenderingbelow(Figure7),therearecausticsontheflourandintheglasses.Thisimageisgeneratedwiththeaidofavraytutorial.(18)
Figure7:Especiallywhenrenderingglassandmetallicmaterialcausticscanbegenerated,asin
thisimageonthefloor.
2.2.3 Anti-Aliasing Filters
Originallyaliasingisanaliasofoneuniquesample,whenyouusethesameinformationover and over again, a pattern of these identical parts may appear if you have notsampled the original information high enough, and form a distortion in the image
edge.Thisproblemcommonlyoccurswhenanimageisgivenalowerresolution.Antialiasing is exactly what it implies, a counter measure to these aliasing effects, a
mathematical cure to the problem with undersampling or low resolution images.
Whatan
anti
aliasing
filter
actually
does
is
that
it
distorts
or
blurs
the
original
shape
edge, fooling the eye where it is more exact than it actually is. There are manydifferenttypesofAntialiasingfilters,foundintherenderingwindow.
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Someof themjustblur thejaggededges,othersjitters theoriginalpixelwhileothermethodschangesthetoneofthecolortone.
Vrayoffersbothsharpeningfilteraswellassofteningfilters.Thedefaultfilter isthearea with a variablesize filter. The parameter can change from 1.0 to 20.0 where
smaller size means a sharper result, as for example 1.5 which is at default. The
Blackman
works
equal
to
the
sharpen
filter
in
Photoshop,
though
without
extra
parameters to control. The CatmullRom gives a similar sharpen effect like theBlackman, but it even slights the edgeenhancement. There are no controllableparameters in this filter either. Another sharpening filter is SharpQuadratic 9pixelreconstruction filter from Nelson Max. Especially in animation sequences it is notalways wanted to sharpen details, but provides a smoother look. The filters such as
Cubic,Quadratic, Soften orVideo can be applied. Some filters can both soften andsharpen,forinstanceCookVariablewithvaluesof1.0to2.5forsharpeningandhigher
valuestoblurtheimage.EvensoMitchellNetravaliisworking,wheretheuserisgiventovalueanisotropytoblurandringing.Bothvaluesvanvaryfrom0.0to1.0while0.33
isdefault.WhilerenderingshotsusingdepthoffielditcanberecommendedtoapplyBlend,sincethisfilterblendsbetweensharpareasandGaussiansoftenfilters.
It
often
takes
some
experimenting
time
to
achieve
the
best
result
for
a
particular
image.(9)
2.2.3.1.1 QuasiMonteCarlo
Monte Carlo is an algorithm simulated by computers and used in a wide area ofexpertise. This simulation is most useful when calculating things that have a largedegreeoffreedom,suchascellularstructuresorfloatingliquids.MonteCarlohasalsoproven to be very valuable in computer graphics, whilst calculating the globalilluminationbecauseofitsuniqueabilityofrandomlyfindingthecorrectresult,aswellas being very precise. The only downside in this context would be the highlydemandingcalculationtimes.
QuasiMonte
Carlo
on
the
other
hand
is
pretty
similar
to
the
regular
Monte
Carlo
method. Thedifference is that the Quasiversion works with numbers that are in anorderedsequence,whiletheregularoneusespseudorandomnumbers,whichmeansthat the numbers seem to be random but are not. This is why the Quasimethod isfasteringeneratingaresult.
AswritteninthehelpfilesfortheVrayrenderer:TheQuasiMonteCarlomethodfor
computingglobalilluminationisabruteforceapproach.Thisisextremelytrue.WithintheboundariesofGlobalillumination,theQuasiMonteCarlomethodrecomputesallpixels in the whole scene that are shaded and calculates upon it individually. Thismightseempeculiar;however,itisalsoextremelyaccurate.(11)
2.2.3.1.2 Photonmap
As previously mentioned, radiosity and raytracingbased methods are combined inhybridtechniques,sinceradiosity isefficientatdiffusereflectionwhereasraytracingcreatesgoodspecularreflection.Photonmappingtakesanalternativeapproachthanthehybridtechniques.Withphotonmapping,theinformationisstoredaspointsinthe
photonmap,whichisaseparateindependentdatastructure.Thelightsemitphotons
thataretracedthroughthescene,reflected,refracted,absorbedorscattered,buildingthe photon map that contains information about all photon hits. Especially in verycomplexmodels, thisprocesscalledphoton tracingsimplifies therepresentationandmakes the rendering process more efficient. This advantage is based on thefunctionality of the photon maps illumination that is decoupled from the geometryand allows handling even arbitrary surfaces. The photon map can be seen as a light
cache inbidirectional path tracing, which means sampling the image both from the
lightsources
(such
as
caustics)
as
well
as
from
the
observers
point
of
view
(such
as
mirrorreflections).Inthesecondpassthe imageisrenderedusingtheinformationinthephotonmap.(4)
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2.2.3.1.3 LightCache
Lightcachingalsoknownaslightmappingisaprocedurethatisverysimilartophoton
mapping,although,itisconsideredtobeitsreplacement,becauseofitssuperiorityinmostcases.Lightcaching issimilartophotonmapping,but insteadofcalculatingthe
lightemittedfromallthelightsources,thepathistracedfromthecameraandintothe
3D
structure.
Then
the
accumulated
energy
is
stored.
Advantages
using
light
caching
instead of photon mapping are for instance a functioning use of skylights and omnilights.Lightcalculations incornersseemmorecorrectand inmostcasesthepreviewresultsseemveryquick.Althoughsimilartothephotonmap,lightleaksmayappear,aswellastheuseofbumpmappingdonotworkeverytime.(11)
2.2.4 Bump Mapping
Bumpmappingisamethodwherethecamerahasbeentrickedtointerpretasurfacedifferentfromwhatitactuallyseemstobe,withthehelpofabumpmappingtexture.
Applingaspottedtexturetoasphere, itwillappearsimilartoaballwithmanysemideep holes in it. There are two methods for Bump mapping in the field, real Bump
mappingandfake.
The
real
Bump
mapping
method
takes
each
pixel
from
the
Bump
map
texture
and
calculatesaheightmapfromit,penetratingthesurfacenormalandbinormalateachrenderedpixelofthesurface.
ThefakemethodsofBumpmapping,alsocalleddot3Bumpmapping,isoftenusedin3Dgraphicsforgames. ItworkssimilartoNormalmapping,because itusesatexture
mapwithcolorinsteadofagrayscale,deliveringalotmoreinformation,whichontheotherhandismoretimeconsuming,too.Thecolorsblue,green,andredrepresentthenormals x, y,andz in 3d space.Eachpixel in the Bumpmap texture is treated as avertex, which is placed upon the material, where the object has a whole newappearance.(19)(20)
2.2.5 Displacement MappingDisplacementmappinggivesasimilarresultasbumpmapping,exceptitdoesnotalter
thewaythecamerainterpretthenormals.Instead,italterstheactualgeometry,whichcan cast shadows, occlude other objects, basically everything a real geometry does.
The first renderer available, that could create a Displacement map, was PixarsRenderman.TheRendermanrendererusedamethodcalledmicropolygonrendering.
Every pixel in the texture for the Displacement map was treated as a polygon. Inprograms such as zbrush, this map for the Displacement can be created and then
appliedtotheobjectinthe3Dprogram.(21)
2.2.6 High dynamic range imaging
Thehumaneyeworksveryefficientwhen itcomestofastadaptiontochanging light
intensities.It
has
the
possibility
to
distinguish
millions
of
detail
in
color
and
intensity
bothonthebeach,abrightsummerday,andinadarkroomlitupwithcandlelights.Even if thedaylight is much brighter than thecandle light, theeyecanadapt to theintensity. This adaption makes it possible to see details both in a dark room andoutside the bright window. A standard camera cannot adapt to several differentexposuretimes.Thatiswhytheimagehaseitheroverwhiteareasasinthewindow,
oroverblacksinthetoodarkroom.
Today,HighDynamicRangeImagingorHDRIisafrequentlyusedlightingtechniquein3D,whichmeansgettingthemaximumofcontrastinapicture.AnHDRimagehasanextra floating point value associated with each pixel that used to define thepersistenceoflightatthatpoint.Whenitcomestodescribingthelightvaluesperpixel
precisely,
a
low
dynamic
range
image
(like
every
usual
jpg
picture)
has
a
limitation
of
250:1. The dynamic range for human eye is about 10.000:1. Some of the HDRIs canhavearangeofover100.000:1.Theonlyproblemisthatacommonscreen,monitororprinter cannot reproduce this high dynamic range because of their limitation to 256
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intensity values. Therefore, you have to convert the HDRI to a LDR with a processcalled tonemapping. This includes a range of different methods to get an infinitedynamicrangetoalimited(0or1).(22)
AnHDRimagecanbetakenasseriesofseveralpictureswithchangingexposuretimes.
Ithastobeastillpicture,photographedfromthesameposition.Theshiftingintensity
in
the
pictures
from
over
white
to
over
black
demands
the
compositing
process
afterwards.
HDRI is mainly used for coherence because of its ability to mime the real world,especiallyusefulwhenworkingwithreflectiveobjects.Forinstance,anHDRIimagecan
betakenoftheenvironmentandthenbeappliedtotheobjectsscenein3D.
ItcanalsobeveryusefulforImagebased lighting,wheretheHDR image(Figure8)is
used for emitting the light or photons from a sphere around the scene. It is oneapplication where a high range of color and intensity is required to illuminate the
sceneinarealisticway.Oftenthoseimagesarealsopanoramas,tobeemployedonasphere.Sucha360angledimagescanbetakenphotographingaspecialmirrorsphere
that reflects the whole environment, but not the camera itself after retouching thepicture.Becauseofthespheresroundingtheimage,theybecomestretchedsimilartothe
fish
eye
effect.
Then
the
HDR
image
has
to
be
mapped
on
a
sphere
in
the
3D
scene.(23)
Figure8:AHighDynamicRangeimageforimagebasedlighting
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3 VISUAL RESPONSE
In this chapter, visual response, the artistic side of imaging will be analyzed deeper.Whatmakesapictureappearsgoodorcomfortable,interestingandmodern?Whatofdoestheimagesharmonyconsist?Whatismeantwithafeelforimages?
3.1 Photography as a starting point
Duringour
research
period
we
obtained
the
opportunity
to
visit
IKEA
Communications
AB, inlmhult,Sweden. IKEACommunications istheheadquartersforall IKEA imagesynthesisandphotography.Mostofthephotographicaltheory,suchassettingupthe
lighting,isbasedonthephotographersexperience,andthereforedoesthefollowingstudymostlyreflectIKEAsfeelingforimages.
3.1.1 Realism
3.1.1.1 Lighting
3.1.1.1.1 Basicthreepointlighting
Lightingcan
virtually
be
seen
as
amodeling
tool
that
is
why
the
three
point
lighting
has
becomestandardinlightingthreedimensionalforms.Asthenameimplies,thelightingsetupconsistsofthreelights,withaspecificfunctionforeachoneofthem.
The key light or main light defines a scenes dominant lighting with the highestintensity of the three lights and also casts the main shadows. It generally is placed
abovethesubjecttosomedegreeandbesidethecamera.Ontheotherhand,aroomsetmayrequirethekeylightatthepositionofabrightwindow,illuminatingthescene
withdaylight.Evenplacingitbehindtheobjectcanbedesirabletoemphasizeamoredramaticfeeling,presentingonlytheobjectssilhouette.
Thefill lights main function is to light up the scene from the key lights oppositeposition. This light is especially needs to open up the key lights shadows, reducing
theirdensity.
Rendering
with
ray
tracing
and
global
illumination
already
includes
that
lightisbouncingbackonsurfaces,indirectilluminatingthesceneasthefilllightdoes,butevenmorerealistically.
More depth can be achieved with the help of a back light, which is essential forseparatingtheobjectfromthebackground,especiallywhileworking insimilartones.
This light is can also be called as hair light or shoulder light, when filming portraits,givingatouchofgloworhighlighttotheedges.
In thephotostudio, the fill light and the back lightcanalso bejustreflectorplanes,which open up shadows or reduce some bright, unwanted reflections. These planesareoftenwhiteorblack,butevensilvercanbeusefulforsecondarylighting.(9)
3.1.1.1.2
Hardandsoftlight
Different types of light intensity and power cause different expressions.Hard lightcreatesastrongcontrastwithbrighthighlightsanddark,sharpshadows.Direct light
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Photorealisticrenderingwithvray|23
from a lamp can often generate such hard light, which often provides suspense anddrama and intensity to the scene. An indirect lighting creates softer shadows andsofterhighlightsontheobjects.Thiscanbeachievedthroughturningthelamparoundand illuminate a big white or metallic reflector, where the incoming light from thelampbouncesoffandintothescene.Especiallyforacozyindoorfurniturescene,suchlightingwillbedesirable.Andespeciallyforsceneswithwindowlightingupthescene,
indirect
light
is
more
realistically,
since
the
outdoor
light
is
bouncing
around
a
lot
beforehittingthewindow.
3.1.1.1.3 Warmandcoldlight
Asseenin IKEAshugephotostudio,thephotographersactsimilartoartistsuntilthefinalpictureistaken.Theyaremodelingwithlighttoachievethebestcontrast,depth
andfeelingintheimage.Butnotonlyreflectorsandwhitelampsareessentialforthecreationofthe image,buteventhe lightscolortemperature.Havingacloser lookto
the white lamps with special measuring instruments, quite huge aberrations fromwhite can be detected. In some cases the color temperature is even shifting from
bluish to yellowish, for instance. While the photographer may be is struggling withtheseeffects,themathematicallyexactlightin3Dmayneedafewmoreofthoselivelylights.
As
the
photographer
can
experiment
with
several
colored,
transparent
plastic
foils,thesyntheticlightsin3Dcanchangecolor.Asdescribedbefore,thelightscolortemperature varies a lot depending on its type of light source, such asdaylight with6500 K, as white light, or a candle light with about 1900 K, as very red and warm
light.
Thewholetricktoachieveaharmonicbalance inthe image istomixcoldandwarmlights(2).Coldorvery light isoftencomingfromoutdoor,thoughawindowordoor,
for example while lamps of the brand tungsten (between 32003400K) in indoorlighting spread warmer light, creating a balance between blue and yellow, or cold
andwarminthescene. Itwillfurthermoregenerateafeelingofdepthandspatiality,astheplaywiththebacklight.
Figure9:Usingwarmandcoldlightinanimagegeneratesafeelofdepth.
3.1.1.1.4 Indirectanddirtylight
Withoutevenhavingturnedononesinglespotinalightsetup,socalledindirectlight(2) from the surrounding, the photo studio is bouncing around and lighting up
everything.Thatisalargeamountoflightincomparisonwiththevirtual,totallyblack3Dscene.This indirect lightcomesfromother lightingsetups,reflectedonwallsand
ceilings or windows, spreading daylight, and is nearly impossible to control. Though,thislightcanliftupthesceneimmensely,makingitmorealive.
Evenwiththebestandmostexpensivelightingequipment,alampcannevergenerateatotallyevenspectrumoflight.Therearealwaysminimalirregularities,whenthelightfromthelampisshiftingfromwarmtocolderlight,whichcanprovidesomeusefulandsuggestiveunbalances.Thislightcanbeseenasdirtylight.
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3.1.1.1.5 Shadows
Shadowsareessentialfortheimageandtheimagesexpression.Withoutlightthereis
onlyshadow,andwithoutshadowthereisnodepth.Inarealworldscene,lightalwayscastsshadows. In3Dtheshadowcanbeturnedoff,whilethe light ison.Those light
settings can create excellent artistic effects, although they can cause an unrealistic
feeling
in
the
image,
too,
because
of
the
lack
of
shadows
where
the
observer
expects
them.
3.1.1.1.6 Reflections
Theusageofreflectionsinphotorealisticimagesisveryimportant,becauseoftheeyes
amazingabilitytonoticeirregularityandthingsthatseemoutoforder,suchasaglassthatwillnotbereflectiveatallorreflectssomethingthatistotallyoutoforder.Thisis
anexcellenttopictoincludeHDRI.BecauseoftheHDRimagesabilitiesintegratedina3Dprogram,theimagedeliversveryuseful,crisp,sharpandrealisticreflections,whichimprovesthefeelthatthesurroundingsarerealistic.
3.1.1.2 Perspective
In reality, different cameras are used to either generate photography or film andmovie production. In 3D, applications the camera is capable of both, making the
render process possible. In this research, we are concentrating on the photographyaspect. Even rendering from a view port is in fact working as a camera although
creatingacamerawillprovidetheuserwithvaluableparameterstocontrol.
Perspectiveisachievedthroughdifferentcameralenses,whereforexample50mmisthestandardlensfor35mmcameras.Changingthelenssizeleadstotheillusionthat
the cameras distance to the objects has changed. This includes distortions ofperspective. A 35 mm lens is called a lightwideangle. A 25 mm lens is a stronger
wideangle,whichstretchestheperspectiveevenmore,withtheresultthat itgetsabigger fisheye effect. A wideangle has a short focal distance, but a wider angle of
vision.Standing
in
front
of
abig
tower
for
example,
can
require
awide
angle
to
fit
the
wholebuildingintothepicture.An85mmlensiscalledlittletelephotolensorportrait
lens, because of its little loose of perspective. This results in a portrait with lowerdepth,whichmeansflatteningthefacea littlebit,wherethenose isnotstickingouttoomuch.Zoomingwith lenseswitha100135mmwilldecreasesthedepthandtheimageappearsmoreflat.Alargetelephotolensisabout200mm.Dependingonwhicheffectsarewanted, thecameradistanceto theobjectand/or the lenssizehas tobe
adjusted.
3.1.1.2.1 DepthintheimageDepthoffield
An image is always twodimensional, even if it was created in 3D. One of the majorproblems tostrugglewith is the illusion ofdepth in the image.Manyphotosappearflat and distracting. The whole trick is to catch the observers glimpse and lead itthroughtheimage.Thereareseveralwaystodothis,whereasthetoolsarealwaysthesame: the lines and forms in the image, their relations to each other and light andshadows. In the later case the photographer can for example chose a darkerforeground,whilethemainfocusliesinthebrighterbackground.Theobserverabsorbsintothepicture.Evenifthecontrastisnotthatextreme,thelightintensitydecreasesgettingnearertothepicturescorners.Thiscreatesaninvisibleborderthatkeepsthe
observerinsidethepicture.
The feeling ofdepth canalso be accomplished througha technique calledgradation(24). Ifanelement,adetailorapartofthescenepartlycoversorhidesanother,theobserver immediately realizes one object as near (in foreground) as the other (in
background)(Figure
10on
page
25).
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Photorealisticrenderingwithvray|25
Figure10:We immediatelyrecognize thattheblacksphere isnearest,since it is largestand in
frontoftheredandthewhiteone.
Thehumaneye istrainedtoseethingseveryday.Fromthebeginning,wehavebeenstudying objects and especially their size. This experience is important to estimatedistancesandspeedsintherealworldandinanelaboratedphotoaswell.Thelonger
thedistance
between
the
eye
and
the
object,
the
smaller
the
object
appears
to
be.
Biggerobjectsareoftenplacedintheforeground(24).Nevertheless,therelationshipbetweenobjectsismuchmoreimportantinthiscase.Atalltreerequiresacomparisontootherobjects,forexampleahumanbeingorahouse,sothatourexperiencecounts
astrueorrealistic.
An additional method to attain spatiality in the image is to work with thedepthof
focus inphotographyordepthoffield,as it iscalled in3D.Asmentionedbefore,thehumaneyecanonlyseesharpwiththecellsinthecenteroftheretina.However,sincethe eye is permanently moving around, our brain gives us the illusion that we seesharpthewholetime.Thedalliancebetweenthemovesistoosmall,lessthanwearerealizingthem.Butinphotography,thedepthoffocusgeneratesacenterofattentionintheimage,andleavesthemurkypartsasrespectively,fore andbackground.Thereare two types of depth of focus: short and wide. As itsname implies, a short depth
means that only a little part of the scene lies in the sharp region, while the rest ismurky. Usingawide depthof focus,hence the name, everything in the image lookssharp (24).This iscommon touse formore technicalpictures,as forexample IKEAs
Guideline images for their products database or the clean presentations in theircatalogue.
Depth of field in 3D works principally the same way, though it is very expensive in
rendering,inthesenseoftimeconsuming(Figure11).
Figure11:
An
image
rendered
with
Depth
of
Field
on,
with
the
focus
on
the
black
sphere.
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Photorealisticrenderingwithvray|26
3.1.1.3 In contrast to 3D
3.1.1.3.1 Noise,Softness
During the 19th
century, there started anewepoch in both literature and art that iscalled classicism. The artists were searching the truth mainly in nature. The Frenchartists and chemists LouisJacquesMand Daguerre and Joseph Nicphore Niepccreatedthefirstpermanentphotographybasedontheprinciplethatasilverandchalk
mixture darkens under exposure light, discovered by J. H. Schultz in the early 18th
century.Fromthismomentthephotographyreflectedtherealityinawayoilpaintings
nevercould.Ittookalongtimeuntilthecoloredfilmreallybrokethrough,wherethephotography felt as trustworthy as today. Nowadays, most of the huge photo
productionsforIKEAaremadedigitally.(24)
Producing a photo with a digital camera includes minor noise, while renderinggeneratestotallycrispyandcleanimages.Thisnoiseisgeneratedfromthecameras
change coupled device or color capture device (CCD) chip. This device uses lightsensitive material on a silicon chip to electronically detect the lights photons. This
incomingsignalistransferredfurtheralongarowofseparatepixels(pictureelements)
whereit
can
be
stored
as
color
information.
When
the
pixels
are
arranged
in
rows
and
columns,theassemblage iscalledtwodimensional.Acolor imageCCDsensorusesacheckerboardpatternofcolorfilters,representingthethreeprimarycolorsred,green
andblue.Alternatively,threeseparateCCDsensorsareapplied,onforeachcolor.(25)
3.1.1.3.2 Roundedcorners
Building object in 3D is similar to creating them in a mathematical correct way. A
polygonobject ismadeoffaceswithoutaphysicalthicknessas inreality.Evenathinsheet of paper has a depth. An equal problem appears on corners and edges. Real
objectscanhardlybeashardedgedastheyarein3D,whenstartingwiththecreation.The modeller has to be aware of those problems and correct them, at least for
photorealisticrendering.
3.1.2 Making the picture alive three main forces
3.1.2.1 Flaws in the perfected
Evenifthehumaneyeisphysicallyandbiologicallynotthebestorsophisticatedone,itcooperatesperfectlywiththebrain.Thisprovidesuswiththecapabilitytorecognizepeople,movements,pictures,andpatternsofeverytype.Particularly,when itcomestosymbolsandsignsthehumanbeing isquitefastandflexibletocommunicatewithother people, due to the evolution. On the other hand, in some areas, this exactlyability to recognize a pattern is not wanted, for instance in design and imagery.Recognition of patterns leads often to a feeling of boredom, although the observer
wantsto
experience
excitement,
suspense
and
harmony,
or
just
detect
athought
or
storybehindtheimage.
The secret of producing harmony do not lay in the construction of strait lines andanglesorinanimage,preciselydividedinequalpieces,butratherinafineinterruptionof lines and surfaces. Although the question about good, bad, beautiful andunaesthetic is very subjective, there are three main ideas to create a goodlookingimage:content,(clipping)detailandcomposition(24).
3.1.2.1.1 Content
The content should reflect the photographers meaning behind the image or whathe/shewantedustoseeorfeel,eveniftheobserverproduceshisowntruthaboutthe
picture.
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3.1.2.1.1.1 ProppingProppingmeanstoplaceseveralobjects intoaroomsfurnitureorequipment,asforexample a couple of books in a bookshelf. Visiting IKEAs store or browsing the
catalogue, itbecomesclear,whypropping isveryuseful.Aboveall,abookshelffilledwithbooksandthingswillbebettersoldthananemptyone.Proppingmakesitmore
realisticlooking
and
personal;
it
provides
the
feeling
of
someone
actually
living
in
the
chosen environment. It can also inspire the customer how to combine their own
belongings.Aroomsetsproppingproducestheillusionofpeoplespresence,andcanalsotelltheviewermoreaboutwholivesthereandhowtheylive.Finedetailscanforexamplerevealwhetheritisafamilywithchildrenorayoungcouplewithpets.Thisisessentialforphotorealism,especiallyforIKEA.However,itstillhastobeaccomplishedwell and considered. Colors have to match to each other and all objects should be
placedharmonicallyandinthesenseofthecontent.Themeaningwithproppingistoillustrate the functionality or to emphasize the design with forms and colors (Figure
12). The number of propping elements depends on the scene, the light, thecompositionforall.Lessproppingoffersmoreownreflectionbytheobserver,though
the trick lies in finding a good balance inbetween the overcrowding and the
emptiness.
That
motto
for
minimalism
is
called
Less
is
more.
Figure12:Proppingpersonalizesaroom(26)
3.1.2.1.2 Clippingandformats,2832,55
Theborders
of
images
can
decide
as
well
how
the
image
feels
and
what
it.
By
clipping
offsomeessentialdetails,thecontentwillchange,too.
There are various formats, rectangular or quadratic. The first one can either be
landscape also called lyingformat, orportrait as a standingformat. As the nameimplies the landscape format appropriates for wide angled views, whereas smaller
subjects as a person, a portrait, comes out more harmonic in a smaller, but longerformat.Choosingaportraitformatforalandscapepicture,canconveyarestrictinganduncomfortable impression to the observer, standing in a room, watching through adoor(24).
Already 300 BC, the Greek mathematician Euclid described in one of his books the
godlyproportions,theGoldenRatio.Itcanbeexplainedasaline,dividedintwopieces
Aand
B
in
such
away,
that
A
is
to
B,
as
B
to
A+B
(Figure
13).
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Figure13:TheGoldenRatio;AistoB,asBtothewholedistanceA+B
The Italian mathematician Leonardo Fibonacci (c. 11701250) found a series ofnumbers,theFibonaccinumbers,whichmaketheGoldenRatiomoreunderstandable:
1, 2, 3, 5, 8, 13, 21, 34, 55,89, 144, and so forth, building the algebraic sum of theprecursornumbers.
2000yearsago,theGreekarchitecturesbuildtheirtemples inthisperfectratio,as
well as many formats especially for papers and magazines are orientated to theseproportionsuntiltoday.Themostcommon formatforphotos is13x8cmasshown
below(Figure14).
Figure14:Thisformat13x8isacommonstandardforphotographs.
Thequadraticformatseemsasaverystaticandunchangeableone,andthereforeevenboring. It can be very exciting in combinations or for itself claiming an interestingcontentandcomposition.
3.1.2.1.3 CompositionImperfectmakesperfect
Nomatter
the
clipping
or
the
content,
an
image
needs
astructure
and
some
kind
of
considered composition, to be able to communicate with the observer. Thecompositionshallemphasizetheimagesmessageandthecontext,inwhichtheimage
isplaced.
Centering an object in the exact middle of the picture will generate an axialcomposition, which meanssymmetry, since thehumaneye often longs forcalmandorder. Placing the center of attention out of the middle of the picture, thephotographerproducesmoreexcitementandlife.Theasymmetryprofitsfromemptyspaces and their relation to the center of attention with different objects. Anasymmetricplacementofequipmentofferssometimesaneasiermethodtocatchthe
observersattention,sohefindsawayintotheimage.Itisalsopossibletoarrangethe
composition
by
the
Rule
of
Thirds
(24),
cutting
it
into
three
parts
and
placing
the
main
object of attraction in the left or in the right division. This method is similar toproportioningaccordingtotheGoldenratio.
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Goodcompositionscanalsobecreatedwithcontrastsinsize,form,color,andsoforth.Thiskindofcompositionisabouttoemphasizecertainpartsintheimagewiththehelpof opposites and their effect to each other. This can accentuate for example a littledetailinthescene.Theruleistoavoidplacingtwoobjectsofthesamekindnexttoeachother,withthesamecolorvalue,saturation,orsizeandform(24).
Another
method
to
elicit
action
and
dramatic
from
an
image
is
to
construct
a
diagonallydirection with elements, surfaces and lines. The eyes automatically followthe lines into the depth of the picture, some kind ofcentered energy. However, thediagonal is also a very symbolic element, especially for Western people, writing andreadingfrom lefttoright.Whenthe line isstrivingupfromthebottom leftcornertothe upper right, it is a symbol of success, positive progress and opening, while the
oppositedirectionoftenmeansblockadeandprohibition.
The question is why does IKEA of Sweden want to place its furniture in a closedangle?BengtLarsson (2)providesaplausible,probableexplanation: It istotallyright
thatamaindiagonalgivesastraitdirectionandspeed toan image,but it isjustas
importantwhichobjectsareplaced in the scene.The image consistsofbalanceand
oftenseveralfieldsofattention,wherediagonal linesareusefulamongothers. IKEAs
Guidelinefurniture
is
always
placed
on
adiagonal,
falling
lines
with
an
angle
of
5
or
11,dependingontheobjectssize.Therefore,evenifthemaindirectionisadiagonal,theobjectoffersother lines thatarestrivingupagain.The imageof thesofa (Figure
15),thatBengthassentusmakesthis ideaclearer.Theobserverseyeswanderfromlefttothemiddleoftheimage,wheretheywillbestoppedandliftedupovertheback
support.Thislittle,shortbreak,whichtheeyestakeinthemiddleofthesofa,createapleasantfeelingofrestingandrelaxing,whichisdefinitelywanted.(2)
Figure15:BengtsexplainingimageoftheIKEAangle.Thesofaaboveispositionedintheright
angle,whilemirroredthesofabelowgeneratedunwantedfeelings,whenitcomestofurniture.
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Whenmirroringtheimagehorizontal,thesofastandsontherisingdiagonal,andthenother unwanted byeffects will appear. First of all, the arm rest is blocking theobserver, while the eyes try to wander from left to the right. The sofa feels morerepelling,notinviting.Andwhilethefirstpieceoffurniturecatchestheobserversviewandreturnshimacomfortablefeeling,thesecondoneforceshimtoslideoutofthesofa, meaning he is not staying on the furniture. Details will be lost and the image
cannotcreate
the
wanted
pleasurable
feeling
of
rest.
(2)
Summarizing, it supplies one main factor to consider while creating a goodcomposition. An image without objects has no composition. That is why, thecompositor shall be aware of all visible objects in the scene and how their lines areworkingincombinationandrelationwitheachother.
3.1.2.1.4 Virtualphotorealism
There are many details in the real world that the observer sees unconsciously andtakesthemforgranted.Whiletheinteriordecoratorironsthingsasblankets,pillowsormattresses to get them creasefree, the 3Dartist struggles with creating accessoriesand fabric furniturewithseemsandstitches.This isachievedwith thehelpofbump
mapsor
displacement
maps.
The
photorealism
lies
somewhere
in
between,
depending
onmaterial, lightinganddistancefromthecamera(2).Materialsshall live:creasesin
fabricandcloth,natural irregularities insurfacessuchaswood!Nothing isdead leveland uniform. Breaking the perfectness makes it more acceptable for the eye and
thereforeevenmorecorrect,orphotorealistic.
Even the variation of textures is very essential for photorealism, since there are norepetitions of surfaces or texture in the real world. It facilitates the work of the 3Dartist,havingahugetexturelibraryathisdisposal.
3.2 Perception Psychology
Psychologyisthestudyofthementalprocessesandbehaviorofabrain.Perceptioninthe fieldofpsychology,on theotherhand, involveshowthebrain interpretsobjects
using the senses. In this research, only one of the senses will be investigated, thevision,whichistheabilitytodetectandunderstandelectromagneticwavesoflight.
3.2.1 Relative Brightness
A very strange and subjective question is how bright are things? A good example is
described in a book, written by Arnheim (27): It has often been observed that a
handkerchief atmidnight lookswhite, like a handkerchief at noon, although itmay
sendlesslighttotheeyesthanapieceofcharcoalunderthemiddaysun.Thisprovesthat brightness is a relative thing; it all depends on the distribution of light in the
environmentor
image
and
the
optical
psychological
process
of
the
eye
of
the
observer,
as well as the nervous system. This is also relative on the objects material ability toreflect light. Another example is if someone sits in a room at dawn and watches
television,focusestheireyesonthetelevisionscreen,andsomeonewalksintheroomlater on and states Why are the lights not turned on? flips the lightswitch, and it
becomesclearthatthesunhassetandtheenvironmentismuchdarkerwithoutevernoticing.Thisisalsothehumanmindworkingtogetherwiththepupilsoftheeyes,the
pupils grow wider to catch more light, as well as the mind compensating withunderstandingoftheenvironment.(28)
3.2.2 Color interpretation
The physical principles of how humans acquire and interpret the color in our
environmenthavealreadybeencoveredinthesecondchapter,butnotwhatthebraindoeswiththeinformationgathered.Aballthatcomesrollingacrossafieldcaneasybe
identified because of its movement, or its shape, maybe its texture but probably
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because of its color, unless it is green, which would help it blend in with the greengrass. Althougha redball wouldclearlypaint aclear imageof colors importance forrecognition. With a few exceptions of physical defects and cultural and religiousbackground, everyone interprets color the same way. Even though almost everyonehasauniquetasteorsenseofcolor,weallhaveacommonunderstandingforallcolorsbecauseeveryonerelatestothesamething.Everyoneknowshowagreenappleorthe
colorapple
green
looks
like.
(28)
3.2.3 Shapes and forms
Shapes can be very subjective depending on the viewers earlier experiences andabilitytounderstandandrealize,veryoftentheuseofobjectssothattheshapecanbe
identified as a class of some sort, for example ananimal or a kitchen accessory. Forexample,ifapersonwenttobedlateatnight,whenitisdarkoutsideandmostofthelightsareout,andseesablackshapeonthebed.Ifthispersonlivesalone,thiscanbevery troubling,where ifyouhavea partner thathasgone tobedearlier, it isalmostexpected,andtheshapeisinstantlyrecognizedforwhatitis.
Or, if twodifferentpersons,oneveryproficient in kitchen equipment, theothernot
quiteas
skilled,
and
both
individuals
are
introduced
to
anew
sophisticated
type
of
blade sharpener. The first person might understand the use of the object instantly,whilethesecondonewouldnothaveaclueunlessexplainedtohim/her,thisstrictly
becauseoftheshapeoftheobject.(28)(29)
Figure16:Thisabstractschemeexplainshowthebrainandtheeyeworktogethertoperceivethe
environment.
3.2.3.1 Optical Illusions
Optical illusionsarestimuli that lie in theborder landsofwhat thehuman mindcan
comprehend. An optical illusion in most cases appears when the mind makes anassumptionthatiswrong,orwhenaconstantrecalibrationisforcedbythemind.Asin
the image above, there is aperfect example of how thebrain tries to help the eyesunderstand images (Figure 16). The brain reads them from left to right and takes
straight lines as an aid, as well as continuity. This precise problem is common in
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computer graphics, in theory there is nothing wrong, but in the practical sense, theminddestroystheimage(Figure18).Therefore,itis important,nottoletcolorsburnoutoveralongrange,keepinginmindthattheeyecanswiftlyadjusttosuchburnoutareas and recognizedetails in them. Sowideregions with exact thesamecolor arenotphotorealistic(Figure17below).
Figure 17: The difference between physically and perceived intensity reveal how the eyes
deceivingus.
Figure18:ThesquareAhastheexactsamecolorassquareB,asthesamplesshow.Coloralways
dependsonitssurrounding.
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4 PROCESS
During the firstweeks,bothofushadbeenresearchingthebackground informationfor the introduction part and the theoretical framework, in chapter 2 TheoreticalFramework.Wehavefoundsomeespecially interestingarticlesandevenbooksthatwerepartlyavailableontheinternet.
Then,wewenttoIKEAofCommunicationinlmhult,southernSweden,andlearnedagreatdealaboutthephotographyprocessandtheir3Dstudio.Thatinspiredusbothalotespeciallyforthebackgroundinformationforchapter3VisualResponse,whichis
the
additional
information
to
balance
the
theory
of
rendering.
The
Theoretical
Framework was more difficult to structure and make choices on what was most
importantforourresearch,andwhattoavoidkeepingthisresearchpaperfrombeingtoobroad.
The practical part of our thesis work consists of improving the old 3D image andgettingitmoresimilartotheoriginalphoto.
4.1 Study Excursion Description
Seeing and walking though IKEAs huge photo studio, we gained a great deal of
experience
and
an
insight
to
the
photographers
process.
The
problems,
which
photographersarestrugglingwith,areofcoursenotthesameasforthe3Dartists.Thephotostudio isbuiltasawidehallwith lotsofblackandwhitedraperies, thinwalls,
reflecting walls, and adjustable roofs. The remaining construction components foreachroom,equipmentandfurnishingvaries,dependingonwhichobject,furnitureor
room setting is going to be photographed. Bigger objects as sofas, beds, or roomsetupsdemandmoretime,space,andoftennaturallyamoreadvancedlightingsetup.
Thestudiohaslargewindowsaroundthebuildingswalls;thereforethephotographerhasthepossibilitytomakeuseoftheincomingdaylight;althoughhehastobeawareof that this light is changing during the day, which also can cause problems.Sometimes, theycover thewindowswithmatt, transparentplastic foil,orjustblack,isolatingdraperies.
Thephotographersworkindifferentways,someofthemworkontheirownandsomein larger teamsof twoormorepersons,dependingonhowhuge theobjectsand/or
scenesare.
4.2 Choosing a room
During our field trip, we asked Bengt Larsson for an original photograph of a roomsetting,whichwecanuseasreferenceforour3Dproduction.HefoundanexcellentimageofawhitekitchenthathasbeenprintedintheIKEAscataloguetwoyearsago.Thisavoidssecurityorpublishingissuesforourthesisresearchpaperaswell.
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The immense advantage with this image of the kitchen is that IKEA had alreadymodeled, textured, and lit a whole scene in 3ds Max and rendered a quite goodlookingimage,asatestforpure3Dgeneratedroomsetups.Ourjobistoimprovethis3Dproductandachieveamorephotorealisticresult.
4.3 Image Analysis
4.3.1 Analyzing the original image
Beforestartingwithactualworkin3dsMax,boththeoriginalphoto(Figure1)andthe3d image (Figure 22) has to be analyzed. The main aspects are modeling, lighting,texturing,rendering,andremainingissuessuchascamerasettings.Wehavediscussed
whythe3Dpicturedoesnotfeelasphotorealisticastheoriginalimagedoes.
Figure19:Theoriginalimagewithalightanalysis
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Figure20:Thecolorcompositionisimportanttogiveacertainfeelingtotheimage.Thiskitchen
feels quite clean because of the blackwhite contrast. The other colors attract the observers
attentionand
make
the
room
livelier.
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Figure21:Proppingisimportanttoshowwhoislivingintheroomandhowitisused.
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Figure22:Thisisthe3Dimageoftheoriginalphoto,modeled,textured,lightenedandrendered
byLindaFerroniatIKEA.
4.3.2 Things to change in the 3D scene (Figure 22)
4.3.2.1 Modeling
Ourmaingoal istoachieveaphotorealisticsuperiorlooking image.Sincethere isanoriginalphototoreferto,the3Dkitchenhastobeasidenticalaspossible.Thisiswhy
evensomemodelingchangeswouldhavetoberealizedinthebeginningprocess.
Starting from the top to the bottom (Figure 22), some of the glasses positions havebeen moved around, to avoid toomuch ofa straight order in the glass cabinet.The
doorhandlesseemed toobigandhad tobemovedupslightly.Themetalbarundertheglasscabinetwasmoveddownandscaledup,aswellasthemountingequipment.
Thewatertapwasrotatedseveraldegreestotheleft,thedishsoapsbottlewasscaleddownonethirdandoneofthedishbrusheswasrotatedtoo,wheretheydonothang
onthebarintheexactsameway.
Bothceilinglamps,hangingoverthetable,weretoolargeandhadtobescaleddown
somecentimeters.Agreatdealofremodelingworkwasneededontheairexhausterovertheoven,scalingupthelampsandgivingsomedepthtotheunderside.
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Theovenseemsveryflat, therefore itwasrepositionedslightlyand theovendoor isnow open, creating a natural, narrow gap. The same phenomenon occurs on thekitchendoors, too,wherethegapsweretoosmall.Wechangedthebumpmapwiththemodeled,realgeometry.
4.3.2.2
LightingThe lighting isveryessential for thewholeappearanceofcolors,shadows,andeven
themodels.Afteranalyzingthe3D image,somechangeshadtobeachieved.Firstofall,amainlightismissing,whichlightsthekitchencabinetinthefrontofthepicture.Thislampseemstobequitebright,maybeaswhiteasdaylight.
The second daylight source from the window has been changed; its light focus is
movedmoretothemiddleofthekitcheninsteadofilluminatingonlytherightside.Toachieve the original photos brightness and feeling of openness, this light is the keylight.
The floor is build of dark brown wood boards, somewhat reflecting. That requiresplenty of light, where itdoes not appear as a homogenyblack floor. Threedifferent
coldlights
are
blending
together
on
the
floor:
from
the
window,
the
front,
and
the
secondroomintheleftoftheroomattheback.
Theceilinglampsoverthetablearemoreyellowishthaninthe3Dimage.Toobtainabalancebetweenwarmandcoldlightinthescene(asintheoriginalphoto,Figure19),the ceiling lamps can be opposite pole to the incoming daylight from the windows.Theselampsarealreadyilluminatingwarmerlight;howeverthelampitselfshallshinemoreyellowish,notwhite.Thiscanbepartofthetexturingprocess.Whenthetexture
ofthelampsinsidewasfinishedandlookedgood,thereappearedotherartifacts,suchasyellowdotsallovertheimagefromthelampreflections.Therefore,wedecidedto
achievearealisticlightinginthewholesceneandeventuallyrendertheyellowlampsseparatelyandpostthemafterwards.
All
metallic
materials
appear
very
lifeless
and
dull.
When
the
lighting
is
adjusted,
it
can
stillrequireaHDRIinthetexture.
Overall,wefindthatthekitcheninthe3Dimagewastoodarkandhazy.Animprovedlightingisessentialtoaccomplishtheoriginalimageslightandopenfeeling.
4.3.2.3 Texturing
The texturing process is often very timeconsuming, since every material has to be
adjusted to the lighting. Settings like color, reflectivity or displacement maps oftenneedvarioustweaks.
As mentioned before, the metallic materials have to be more realistic, reflecting aHDRIforexample.Thekitchendoorsarealsorathertoomatt,whiletherealdoorsarevarnished.
The
glass
tops
in
the
glass
cabinet
are
too
green,
and
should
have
amore
bluishtexture.Detailssuchasfixinga labelforthetransparentbottlebythesinkcanaccomplishmorephotorealism,becauseitismoretrustworthywithrealisticdetails.
The oranges do not appear very delicious. The texture should be more orange thanyellow,aswellasthefruitshouldberotatedabit,whereitreflectsthelightfromtheceiling lamps. They need to feel fresh and kind of shiny. Photographing food is ascienceofitsown.
The potholders are more similar to towel fabric. Since the camera focus lies in thebackground,detailsofthepotholdersareblurred.Towelmaterialwillprovideasoftertouchtotheimage.
In
the
original
image,
it
is
obvious
that
the
wooden
floor
consists
of
boards,
while
the
3Dfloorisflat,nothavinganygapsinbetween.Thislackofmodelingcanbearranged
withthehelpofadisplacementmap.
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4.3.2.4 Rendering
Thefinalimagewasrenderedwiththefollowingrendersettings:
GlobalSwitches:Nohiddenlights,nodefaultlights,
AntiAliasing:AdaptiveQMC,CatmullRom
AdaptiveQMC
image
sampler:
min
subdiv
1,
max
subdiv
2
IndirectIllumination(GI):GIcausticsrefractive,primarybounces:QuasiMonteCarlo,secondarybounces:Lightcache.
Lightcache:Subdivs:500800forweb,1500forhighqualityimages(3000px),numberofpasses=howmanyprocessorsareavailable
Environment:skylighton(colorwhite),reflection/refractionon
rQMCSampler:Noisethreshold:0.0005,Minsamples:16,GlobalsubdivsMultiplier:3
4.3.2.5 Problems
Mostproblematic
are
our
insufficient
computer
capacity.
The
scene
turned
out
very
complexandtimeconsumingtorenderonmycomputerortheo