What to look for to get GOOD EDGES when KEYING in NUKE | Comp Lair: Live Tech Corner S01

so of course this is a really open question and let me tell you that there's no perfect solution that's the short answer but i think there's a few things that we should talk about because more than showing you solutions i think it's best to show you what you should look out for because the solution is the combination and the balance between three main areas that i want to call your attention to so the three main areas i'm talking about are the matte the spill and additive as an extra we can also take in consideration the edge extent so as i said my intention here today is not so much showing you the perfect key but rather show you what you should look up for when doing this process yourselves it all starts with the mat of course and there's a few things that i would like to call your attention to so in here i have these two versions of the plate i have one denoise and i have one with normal noise and then i have this background in here the fact that we have tracking markers in here i'm just ignoring this fact because what we're gonna look at is more about these edges which was actually the question let's start with the key light and this is the first thing that i would like to call your attention to and i want to believe that this is not news for anybody's watching this but you should always do the math extraction coming from a denoised plate rather than a nice plate here's what i have but look what happens if you ignore this fact and put this on the noiseplate you see there's good and bad with it the first thing that it's good is you have a lot of detail in here that you cannot have in here so this is one of the first things to watch out for yes it's best to do the matte extraction coming from the deny split but in some areas you might want to use the noise plate without having any side effects like flickering to get all this detail so in here if i don't have any flickering i would probably take advantage of some things in this side that i want to have as my map of course there's a lot of pollution in the background so if i want to go on this route i would probably have another one in here and i would have to clean it slightly either within the whatever gear you're using or with a color lookup which is probably what i would do if you compare now these two solutions you see that one of them will have more detail than the other this obviously it's highly dependent on what was the method that you use or what was the tool that you used to do the denoise but anyway if you have differences like this it's something to watch out for and you can use a key mix to mix these two worlds just on the portions in which you want to take this more in consideration say for example this one here so now we have this thing with more detail but i want to call your attention for something which is it's different if you do a normal key line directly from the plate as we are doing in here or if you do it via a long version of the plot whether it's the true log or an approximation log at the moment i'm just going to put this lock to lean of course now this here is not valid because you know the color that i was picking is no longer valid within the log version of my play so i will have to pick this one again and what i'm trying to get at is the fact that this will also give you different results than this you see that it's not the same so you probably have a better fall off with the log version and that's why these are the reasons why you should have a mat for the core and other mats whether it's one or more than one for different parts of your edges you want the falloff to be just right but you don't want to introduce any holes in your mat which is the case in this version there's a lot of holes in here that you don't want for sure so again it's a matter of balancing different worlds to come up with the best of both of them so i'm assuming that in this case i have the perfect format which is probably not the case but even if it's not the case i'm not going to retweet this because i'm assuming that you know how to do these kind of things it's very easy so let's move on to the next part which is the spill so now that i have my mat i now want to the spill my plate and this is also something that is going to influence your edges quite a lot quite severely and i see a lot of people failing at this stage and where should you do this feel where you should do the spill on the noise version of your plate because if you do it on the noise version of the plate you're possibly going to get artifacts i'm going to show you what i mean by this so i'm going to use my display can use any of the spill you want but look what happens if i do this on the noise version of the plate let's say that i don't want to match the luminance for example so you see that all these artifacts in here will be introduced so you see that this version has a lot of grain for example which is not the same as my actual plate so you are introducing artifacts that you don't want to so it's always safer to do the this video always under the noise version and then we're going to get the original mice back on top in all the different stage so this is another thing you want to watch out for for edges because if you do this feel on the noise version you're gonna get artifacts possibly in the edges as well so now that i have my the spiel version of my plate now i want to copy my map to my display version of my plate and then i want to use the pre-multi in here while in here everything seems kind of alright but we don't know for sure until we start mixing this with the background so let's see what happens i can see i still have possibly a little bit of green and other problems in here so the first thing to do is to come up with the method on the display version of your plate that not only will take the green away but also will make the edge color closer or exactly the same as the edge color of your foreground so whatever color you're putting on the background has to match the actual edge otherwise you're gonna get this transition that depending on the background might not be what you want in this case in here i can see that there's a fringe in here of green and other colors that are not desirable for example in here i have this gray see coming from this background we already covered this i don't want to repeat myself but these two of mine have the ability of actually getting the background color with the same color as where the edge belongs so here's the difference if you don't have this being done in this way looking at the final result you're going to get these differences you see this scene here for example and in here in this fringe as well and all around really so this is another thing you want to watch out for which is how is your the spill being done do you have the right color close to your edge or you have a color that doesn't belong at all with your edge whether you have it or you don't have it let's not forget that this version of the plate is going to be cut with the alpha that you have so if you don't have the enough detail in here you're not gonna get anything being shown anyway so that's why it's important that you get all the detail possible at this stage as well it's better to have it and then you know make a decision whether or not you're gonna use them all or you're gonna use other processes to compensate for whatever problems you might have but it's a very good starting point that you have all the detail possible so in here let's see the difference if we don't mix these two you see why this is important in here so if you wouldn't mix this you're not gonna get this detail so it's very important that you have all the detail possible on the mat side and then as i said make a decision whether or not you're gonna use them okay so we just covered these two important aspects matt and the spiel and hopefully you now understand how this can mean so much for your edges so another thing you want to watch out for is how hard is your math although yes you can get a lot of detail in this case the math is really hard in some areas in here which in this case so different methods of king gives you different results and the reason is this transition here on your mat as you can see now it's really abrupt the actual core part of the gear is too strong and too abrupt in terms of value to that transition to the falloff so we have to watch out for these situations as well so let's go to the different pillar of what makes good edges and let's not talk about the editing so we're not going to get into so much how to do additive keying we already discussed different methods anyway regarding additive king i'm gonna use mine called detail catcher and now i have all this detail nice follow-up you know right colors everything in here let me call your attention for something at the moment i'm using my plate with the noise in it to do this version of my additive and what i'm going to get is probably double grain because i'm going to put another image on top of this one and this one has already some grain in it and that's why you should never do this in this way what you should do is with the denoised version again so now i don't have any noise and now i have all this nice detail that otherwise i wouldn't get it the same way i have all this nice detail in here but look what this is also giving me this will enhance the problem that i have in here anyway this is making this problem even more apparent so again if you have all really well balanced on this side when you go to this side of things everything should fall just perfectly but the thing is we knew from the beginning that we had the problem in here and we could see it even before we had the additive that the problem was here so if you don't take care of these things at the right time when you are introducing other things this will be even more apparent yes you can get more detail in better detail in here everything is really nice in here but this will actually enhance the fact that you have bad edges rather than solving the problem let's assume that for the sake of argument that you did everything that you possibly could and you still have this problem let me tell you that that's not true you can always do things at the mat level and if you do things at the math level this will be just fine but that's when the adjacent can help you but there's very important things to take into consideration on this front i strongly believe that if you have a good balance on all these three things this will not be needed but we know that in reality of productions this will actually happen at some point but you have to be very careful on how you do this and when you do this type of edge extent so first of all at the moment we still are with the denoise plate so that means that we don't have the original grain so i'm gonna put the original grain back on top so now here this will be the original grain another thing to take into consideration when you're dealing with this which will also influence your edges is whether or not you have a really visible fringing with some green i don't think that in this case this will show it but take into consideration that sometimes this method although it's the original grain the fact that you have a fringe like this this can introduce some edge problems so very simply what you can do is you can select just the edge of your character and just drop another the spill like this and then with the key mix you just say i want this to spill just where this thing is so now you're gonna get that being affected just on the edge the rest remains intact and this will be enough for you to not have that problem anymore on the edge if that's the case which in this case i don't think he was showing but anyway this will also influence your edges but as i was saying edge extend destroys your grain because it's based on blurs for the great material of the time or even if it's not blurs it's distortion or something like that which will destroy the integrity of your pixels which will result in some blurriness let me show you what i mean so i'm going to use mine so you can use whatever edge extent you want you see that my pixels are getting a little bit blurred so if you definitely need to do this you have to do this in a very wise way by wise i mean to start with don't do this with the noise we know that we have the noise available somewhere else and then let's say that this is okay so i'm just going to put this as a final result and then i'm gonna unpromote this again so i have the maximum range in terms of canvas to play with and then i'm going to put my noise back on top now i want to copy my alpha coming from my key and then i want to pre-mode this again okay so this way i'm making sure that i'm not applying anything on the premolted version i'm introducing the original grain but before that's when i should do my edge extent not after because it's going to destroy my grain again so all of these things will influence on not only the detail that you're gonna get but also the quality of your edges now i can play with this in a safe way so here's what i need to do first of all this tool of mine is based on a exponential growth of your pixels so this will actually give you very good results as if it was very organically coming from the actual edge see that i have all of those variations in color so let's see what will work if you don't have this yes it's much better okay but you should only apply this where it's strictly necessary you have to be very syrugical in terms of where you are applying this because if you apply this over everything you can get artifacts that you don't want to and i called your attention for for example what's happening in here you see that this is now altering the aspect of your actual plate so this it's not the same as this so you have to be very careful on where you apply this so at the moment i just want to apply this in this area so i'm just going to drop a rotor shape and i'm just going to put the rotor shape where i need it then with the key mix i'm just going to say that i want this pixel stretch just on that region there okay let me rearrange this a little bit better so now if we go on and off you see that you have that problem being taken care of just where it's a problem and not anywhere where it's not a problem so now what you do as a final check is you're gonna get a wipe to see what else you need to do but as you know it's a combination of all of these things at the moment seems like we have a nice level of detail and very quickly so things could be definitely better but it's not bad as a starting point i still think that this area here would require a little bit more help on the mat side of things for example in this area here it's also a little bit too hard still but it's basically how you do it in terms of balancing all of these aspects again it's not my intention to show you the perfect key although this is not bad as a starting point but it's more about telling you how to balance all these things out because this shouldn't be a complicated process at all this should be actually very simple with very simple processes but this is more about balance on all these three factors in here this for me is extra as we just mentioned but these three factors are the most important ones to get things right some people might say that actually having more math is going to cause you more problems than to have less i don't share that view i think all of these things are important and met with all the detail that's possible to get it's a good thing to have not a bad thing to have because it's best to have more and then throw it away if you don't want to have it rather than not have it as a starting point the spill is also hugely important you should tackle this field in the same way that you tackle math in terms of what's the core part and what's the edge part and then the additive you know there's many different processes mine is very simple as i just mentioned many many times but it's something that you should follow any method or the method that you feel more comfortable with so let's not forget also that at the end you know a tiny bit of massaging in the pixels at the very very end can be done not my preference but can be done if it's like just a tiny bit especially if you have like a very very good additive king what i mean by this is you can always go with for example on a road what in a row yes sometimes very very gently even one pixel might be too much something like half a pixel maybe this will massage things in a in a good way for example in here okay and maybe this is already a little bit too much but you have to make these decisions in an informed way and you have to make sure that at least you have the detail on this part in here but the detail on the mat side of things is also very important because probably you will have to at some point render this as a matte for ti or you're gonna need this as a completely separate render so you can provide it for 3d conversion processes for example so the math on that side of things is also very important and it's important all around it's better to have more at the starting point and then throw away the bits that we don't want rather than the opposite because if you don't have it you're not gonna have it at the end by some sort of magic trick so this is my take on your question salvan i hope i answered this question i tried to make it as less boring as possible this is a topic that there's a ton of things out there and that's why i think it's a little bit boring but anyway since we are opening this segment i just wanted to give you my take on it hope you liked it see you next time

Channel: Comp Lair

Views: 2,462

Keywords: nuke keying edges, nuke keying tutorial, nuke keying hair, nuke keying, fix edges, nuke advanced keying tutorial, nuke keying motion blur, keying edges, nuke keying techniques, nuke keying nodes, nuke keying template, nuke primatte keying tutorial, nuke advanced keying, nuke advanced tutorial, nuke chroma keying compositing tutorial, nuke, compositing, comp lair, vfx, advanced nuke, nuke tips and tricks, advanced compositing, the next level, Nuke tutorial, Vfx geek

Id: dLA09Ba-Rmg

Length: 16min 26sec (986 seconds)

Published: Thu Jun 24 2021