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在PS里合成VRAY输出的分层渲染图作者：AhmedFathi教程来源：感谢人家写了这么好的教程Twiceamonthwerevisitsomeofourreader’sfavoritepostsfromthroughoutthehistoryofCgtuts+.Todaywe’retakingalookbackatAhmedFathi’stutorialoncompositingVrayrenderlayersinPhotoshop.ThistutorialwasoriginallypublishedbackinJulyof2010,andgeneratedalotofinterest.Soifyoumisseditthefirsttime,whynotcheckitoutnow.一直以来，Cgtuts+每月都会有两次回顾读者最感兴趣的帖子。今天我们来看一下AhmedFathi的vray分层渲染并在ps中合成的教程。这个教程最早发布于公元2010年7月，并且引起了很多人的响应。所以，如果你错过了第一次，这次为什么来细细研读呢？InthistutorialAhmedFathitakesalookathowtocompositetogetherV-rayrenderlayersusingblending-modesandmasksinPhotoshop.Oncecompleted,thisprocessallowsyoutochangeortweakanyaspectofyourimageinsecondswithouthavingtore-renderathing!AhmedalsocoversafewextrapostproductiontechniquessuchasChromaticAberrationandDepthOfField,aswellashowtoemulateaCross-processedlook.在这篇教程里演示如何将渲染的图层通过Photoshop的图层混合模式、蒙版来合成。一旦渲染完成，你就能分分钟改变或调出你想要的任意结果，而不用重新渲染！Step1Asthisisacompositingtutorial,notalighting/renderingtutorial,I’llassumethatyouhaveatleastabasicknowledgeofV-ray,andthatyouareabletorenderoutyourownscenesalready.We’regoingjumpstraightaheadintosettingupthedifferentrenderelementsforthecompositingprocess.InordertomakeV-rayrenderoutthedifferentlayers,wefirsthavetoenablethemintheV-rayRenderElementstabwithintheRenderSettingswindow.Onceinthetab,wewanttoenablethefollowingrenderelementsasshown:这是一个合成教程，而不是灯光或者渲染教程，我假设你有基本的vray知识，并且能渲出你的场景。我直接跳到如何设置vray元素以用于接下来的合成过程。为了能使vray渲染出不同的元素图层，先得在vray渲染设置窗口的RenderElements选项卡启用各个元素，设置如下图VrayDiffuseFilter漫反射滤光器VrayMtlID材质IDVrayObjectID对象IDVrayRawGlobalIlluminationRaw全局照明VrayRawLightingRaw光照VrayRawShadowRaw阴影VrayReflection反射VrayRefraction折射VraySpecular高光andVrayZDepth.景深Mostoftheseelementsdon’tneedmuchworktogetthemright,butwearegoingtoneedtotakeafewstepstosetuptheVrayMtlID,VrayObjectIDandVrayZDepthlayers.其中的大部分vray元素默认设置就能得到不错的元素图，但其中材质、对象ID、景深元素还是需要我们做些工作滴！Step2We’llstartwiththeVRayZDepthelement.TheZDepthlayerisablackandwhitemapthatisusedtotellPhotoshophowfareachobjectinourscenesitsawayfromtherendercamera–thefurthertheobjectisfromthecamera,thedarkeritwillappearintheZdepthlayer.TypicallytheMinvalueisusedtotellthecompositorwhichobjectswillbeinfocus.InordertocorrectlysetupaZdepthmap,wehavetoadjusttheMin&MaxdistancesthatV-rayshouldcalculate,andthereforewhatappearsaswhite(theMinvalue)andblack(theMaxvalue)withinourscene.SelecttheVRayZDepthitemintheelementslist.Atthebottomyou’llseethezdepthminandzdepthmaxvaluesweneedtoadjust.我们从VRayZDepth元素开始。ZDepth图层是用灰度表示场景中的物体离渲染摄像机的距离，颜色越白离相机越近。为了vray能正确计算景深图，需要测量你想表现景深效果的远近。从元素列表选择ZDepth，在底部有景深最小值和最大值参数，需要你调整。Step3Togetasenseofwhatvaluesyoushouldusefortheminandmaxvalues,youshoulduseatapehelperobjecttomeasurethedistancebetweenthecameraandyourclosestandfurthestobjects.Tosimplifythings,let’ssaysphere#2intheimagebelowistheclosestspherewewanttobeinfocus,whilstSphere#6shouldbeslightlyoutoffocus.WewouldusetwotapestomeasurethosedistancesandputtheminasyourMin&MaxValues.为了得出场景合适的景深最小值和最大值，你会用到helper里的tape对象来测量最近，最远，以及相机之间的距离。简单起见，下图2号球我们想要它在焦里，并且是最近的（再近一点就会模糊的那种效果），同时6号球是最远的，有一点点出离焦（这一块照着英文意会吧，没译好）。然后用两个tape测量它们之间的距离，以作为min,max值Step4Here’’swhattheVRayZdepthrenderforthiscompositelookedlikeaftersettingtheMinto20andMaxto70meters本例中的值大概min:20max:70米（是说房子的场景，不是上图的六个球）Step5TheVrayMtlIDrenderlayercreatesanimagewithadifferentsolidcolourforeachmaterialinyourscene,andtouseit,weneedtoadjustyourmaterialIDs.Inyourmaterialeditoryouwillfindaniconwiththenumber0onit(asshownbelow.)Ifyouclickthe0,agridofnumbersfrom0to15willappear–thisisyourmaterialID.GothroughyoursceneandapplyadifferentnumbertoeachmaterialyouwanttohaveadifferentcolorinyourMtlIDelement.Aswehave16numbers,wecanhave16differentmaterialsappearinginourMtlIDrenderlayer.材质ID图层是由场景中各种材质对应的实色组成，为了能适用，需要调整材质ID，材质调板上有个0的图标，按下后有个0-15的网格显示出来，这就是材质艾迪。检查场景中的材质，并赋予不同的材质ID，16个数字对应16个不同的材质。Step6Here’’showyourVRayMtlIDelementwouldlooklikeaftersettinguptheID’sforeachrequiredmaterial.Yourresultmayhavedifferentcolors,buttheimportantthingisthattheyareseparatefromoneanother.最终分配了材质ID的元素图会像下图。你得到的成图也许颜色和本案中有所不同，但重要的是，不同材质的物体已彼此分开。Step7VRayObjectIDelementisjustlikematerialIDselementmentionedabove,butitoutputsadifferentcolourbasedonthedifferentobjectsinyourscene–theMaterialsareirrelevanttoit.Tosetthisup,rightclickyourdesiredobject,selectObjectPropertiesandgiveeachobjectadifferentnumberintheObjectIDfieldintheG-Buffersection.对象艾迪元素和上面的材质艾迪类似，对象艾迪的不同颜色是基于场景中不同对象输出的，材质都无关紧要。配置，右键对象——对象属性，在G-Buffer框的材质艾迪上给出不同的数字Step8IonlyneededtousetheVRayObjectIDelementinordertomakeselectingthecarsandthesurroundingbuildingseasierinpost.Here’’showitlooksafterrendering.我用对象艾迪只是为了能更方便地选出车辆以及周围的建筑。下面是渲出的对象艾迪图Step9Thelastelementweneedtoaddinistheambientocclusionlayer,butasyou’llremember,thiswasn’taddedtoourrenderelementslistinV-ray.Weactuallyneedtorenderitseparatelyafteryourinitialrenderhasbeencompleted,butdon’tworry,thereisaneasy,fastwaytodoit!ApplyaVrayLightMtltoyourentirescene,andthenaddaVrayDirtmapintothecolorchannel.You’llthenne