How to do CG compositing in NUKE - 01 (Lightgroups and AOVs)

[Music] hey everyone welcome back to my channel my name is lalit desai and i'm a compositor so today this tutorial is going to be an introduction to cg compositing we are going to look at some of the very common cg passes and we are going to see how do we do an aov rebuilt in this so this topic is going to be divided into two parts the one the first part will be where i i'll be explaining how do we do an au aov rebuild and an overview of a lot of cg passes and the second part will be using those geometry passes uh to create mattes and other stuff like adding motion blur or a vector blur and using the focus so let's get started firstly what are light groups light groups are basically the amount of lights or the number of lights that have been used in the 3d package to render out the cg so the 3d package which i used is cleary so this is an rbd destruction if you see which i did in houdini i used the cache in clarisse to light the setup and i've used two lights in this one is in ibl which is an image based lighting and the other is a key light which is an area light to light up uh the screen right section of my cg as you can see that there is a lot there is environment light coming in or the sunlight coming in from the screen right hand side so let us go deep into the cg passes that i rendered so this is the beauty and this beauty has been broken down into light group 0 and light group 1 so these are the whole lot of passes that are rendered these are the basic passes which you will get in production so over here we have light group 0 and lad group 1 and now these light groups are further broken down into direct and indirect passes for diffuse and specular respectively so let us start let us see these passes first this is light group 0 and now i am doing a page down on my keyboard to view these passes from up to down so this so this is my led group 0 beauty this is my direct diffuse this is my direct specular my indirect diffuse if i expose up you will be able to see and this is the indirect specular for light group 0. similarly we have these passes for light group 1 also this is my light group 1 that is my key light beauty this is my diffuse direct diffuse direct specular indirect diffuse and indirect specular along with that we have diffuse overall all diffuse if i if i have to rephrase and i have direct passes which which is the direct all the all of the direct passes in my cg these are the indirect passes all the indirect and we have a whole specular pass so we are going to see uh four types of aov rebuilds which i'll explain in a minute along with that we have motion vector pass we have a position reference pass position world pass we have a depth pass and we have a world normal path so all of these geometry passes which i mentioned so we are going to use these passes for uh creating mattes adding defocus adding motion blur and maybe to re-light or you know do some relighting stuff also i forgot to mention we have an incandescent pass which is just a bounce light which the objects are emitting so let us go to the air variable now also along with this i have rendered shadows reflections for these objects so this is pbr catcher basically clarisse uh has a material known as shadow catcher which gives us these aovs diffuse reflection which is more uh which has more of roughness to its reflection this is the glossy which is like a mirror reflect a sharp reflection and the shadow pass now if you see this is an overall shadow pass which combines both the light groups further you can also break down the shadows into light group 0 and light group 1 but for this simple comp i thought it won't be necessary so i've rendered this as a whole so let us dive into the comp and see how i have done that let us first add the reflections and shadows so this is my diffuse i have reduced some noise by adding a reduced noise node i have graded it made it slightly more visible distorted it now for distortion you can refer to my monolith tutorial as to how i how you can get a distortion from the lens that you shoot so i've done the lens solving and i've got the distortion values and i've used it so this is what you get next is glossy reflection so what i've done is i've taken the glossy reflection i've added some contrast a defocus by keeping the focal point over here to match to my scan small amount of cg blur to make it less sharp as we can see that in our scans or in our footages nothing is as razor sharp then we have our opacity that is our shadows i've used this shadows as a matte to grade i've just slightly increased the intensity used a defocus and then created it so i've matched the blacks of these shadows to the beneath area of my sofa on my bed using a simple color correct node now let us go to our aov rebuild so as i mentioned there are four types of aov rebuilds that you can do so the first one is where we combine our direct and indirect passes so our ultimate focus will be to combine these and match it to our and see that if they match to our beauty or not so i have combined both of these passes these match to my beauty let me just switch off the unpremade over here okay so this combination matches to my beauty so this is correct i have my diffuse and specular which i have combined and this also matches to my beauty so that is fine now the light group rebuilt where i have taken the light groups shuffle the live light groups and the emission pass that is the incandescent pass i've merged them and this matches to a beauty so that is fine the most important one is this light group aov rebuild what i have done is i have splitted the light groups in these four parts which i rendered direct diffuse direct specular and direct diffuse indirect specular i've merged them and i need to match it to my light group zero so this matches so we have a successful rebuild similarly for for light group one i have merged this and if this matches to one at group one then we are going the right way yes it does so we are going to write within incandescent finally i'll merge the incandescent in and this should match to a beauty it does so we are on the right track now if you see i have plused everything so i have lost the alpha so i've just copied the alpha from my beauty over here and we have a pre-mult so before color correcting as if if you have seen my previous tutorials you should add an and remote to avoid getting black edges so this is a motion vector motion blur applied to get reduced noise in my motion blur if you see a very small amount of motion blur is reduced by adding vector blur and we are using the motion vector in this so we'll dive deep into these sections in the next part i've added a defocus to small cg blur will do and finally a distortion and then and the remove node to just keep the rgba so we have two options remove and keep but i'm care so i am keeping the rgba and finally i have my comp so this method is most preferred in production as this gives you a lot of control in very rare occasions or sometimes you can use this method also if you are if your cg is not that heavy and you just have one object then this might do so this is the first pass that you present before your lead or supervisor or whoever is responsible for your shorts delivery so this is how we do an aov rebuild okay and if you have any doubts or comments regarding the aov rebuilds you can comment down below and stay tuned for my part 2 which i'm going to upload very soon and in that i'll be explaining how to create maths how to use vector blur and how to use the depth channel to create defocus so that's it for now guys thank you so much for watching and stay tuned

Channel: Lalit Desai

Views: 5,359

Keywords: cg compositing in nuke, cg compositing, multipass compositing in nuke, Nuke 12, houdini 18.5, clarisse ifx 4.0, direct diffused light, lightgroups, LightGroups

Id: kf1ILIOulVA

Length: 10min 40sec (640 seconds)

Published: Mon Apr 26 2021