BokehLensShaderbyAshAiadAutodeskMediaandEntertainmentDivision

BokehisaJapanesewordfor“blurredorfuzzy”(暈け)

Thisisareallifephenomenonthatoccursinphotographywherethelightsourcesinanoutoffocusareaofanimage.DifferentlensBokehproducesdifferentaestheticqualitiesinoutoffocusbackgrounds,whichareoftenusedtoreducedistractionsandemphasizetheprimarysubject.Forsomereallifeexamples,pleasevisittheBokehpageontheWikipedia.

WecansimulatethesameeffectinMayausingtheBokehLensShaderinmentalray.ThisistherenderwithoutusingBokehasourstartingpoint.

Before

After

OncementalrayBokehLensShaderisbeingappliedtoMaya’sCamera,itwillproducethefollowingeffect,andmuchmore!

TableofcontentTableofcontent........................................................................................................................................... 1

HowtosimulateBokehLenseffectinMaya ............................................................................................... 2

AssignLensshadertoCamera ................................................................................................................. 2

UnderstandingBokehLensshader .......................................................................................................... 3

AdvancedBokehEffect ............................................................................................................................ 8

HowtosimulateBokehLenseffectinMaya

AssignLensshadertoCameraWestartbyselectingthecameraofchoice,andundertheattributeeditorofthatcamera,clickon“LensShader” toassignamentalrayLensShader.

Under“CreateRenderNode”dialog,openthe“Lenses”verticaltabandlocatethemia_lens_bokehShader.

BydefaulttheBokeheffectwilllooksomethinglikethis

Note:TheShaderparametersrelyonthescenesize,thereforeresultswillvaryfromonefiletotheother.

UnderstandingBokehLensshader

On:Thisisatoggleon/offswitchtodisabletheShaderifneeded.Defaultison.Youcanapplyanrenderlayeroverridetodisabletheshaderforspecificrenderlayers,forinstance.

Plane:Isthedistancetothefocalplanefromthecamera,i.e.thepointofinterest.Thispointwillbeinfocusandtherestwillbeoutoffocus.

TogettheproperPlanevalue,wewillusethemeasuringtooltogiveusthatdistancefromthecameratothepointofinterest.

YoucanalsousethecameraNear/FarClippingplaneasamethodtodeterminethedistancerequired.

Withaplanevalueat18.8

Withaplanevalueat8.7

Radius:Thisistheradiusofconfusion.Thisisanactualmeasurementinsceneunits.Avalueof0willresultwithNoBokeh.Thehigherthevalue,thefurtherawaytheBlurwillaccrue.

Fromlefttoright,Radiusat1.0,0.5and0.0

Samples:Themoresampleswehavethebetterthequalityofthe“blur”,howeverthatcomeswiththeexpenseofrendertime.

Fromlefttoright:Sampleat0,24and48

Bias:Lowervaluespushthesampleprobabilitytowardsthecenter,creatinga"softer"lookingDOFeffectwithamore"misty"look.Highervaluespushthesampleprobabilitytowardstheedge,creatinga"harder"lookingDOFwherebrightspotsactuallyresolveassmallcircles.

BladeCount:Thisdefineshowmany"edges"the"circle"ofconfusionhas.Azerovaluemakesitaperfectcircle.Noticetheshapeofthehighlightintheblurredareaoftherenderedimage.

Withbiasat0,noticehowtheblurredhighlightsareperfectcircle.

Withbiasat4,noticethe4cornersintheblurredhighlights.

BladeAngle:Onecanalsosettheanglewiththeblade_angleparameter,whichisexpressedfrom0.0to1.0where0.0iszerodegreesand1.0is360degrees.Theeffectwillbemorenoticeablewhenyouhavehardcornerhighlight(forexample,avalue4orgreater).

WithBladeAngleat0(0degree)

WithBladeAngleat0.25(90degrees).

AdvancedBokehEffect“UseBokeh”and“Bokehmap”

ThisoptionallowsusinganimageasBokehmap.Whenthisoptionisused,theparameters“bias”,“bladecount”and“bladeangle”havenoeffect.ThemapdefinestheshapeoftheDOFfilterkernel,soafilledwhitecircleonablackbackgroundisequivalenttothestandardblur.Generally,oneneedmoresamplestoaccurately"resolve"acustomBokehmap.

Note:Thesizeofthisimagemapdoesnotcontributetothequalityoftherender.

ThefollowingrenderedimagesdemonstratedifferentcustomBokehmaps.