Bokeh Lens Shader by Ash Aiad Autodesk Media and Entertainment Division Bokeh is a Japanese word for “blurred or fuzzy” (暈け) This is a real life phenomenon that occurs in photography where the light sources in an out of focus area of an image. Different lens Bokeh produces different aesthetic qualities in out of focus backgrounds, which are often used to reduce distractions and emphasize the primary subject. For some real life examples, please visit the Bokeh page on the Wikipedia. We can simulate the same effect in Maya using the Bokeh Lens Shader in mental ray. This is the render without using Bokeh as our starting point. Before After Once mental ray Bokeh Lens Shader is being applied to Maya’s Camera, it will produce the following effect, and much more! Table of content Table of content ........................................................................................................................................... 1 How to simulate Bokeh Lens effect in Maya ............................................................................................... 2 Assign Lens shader to Camera ................................................................................................................. 2 Understanding Bokeh Lens shader .......................................................................................................... 3 Advanced Bokeh Effect ............................................................................................................................ 8
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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.
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