Rotoscoping in Nuke Tutorial | 5 Beginner Tips

[Music] rotoscoping and nuke five tips for beginners so tip number one is to identify motion paths so what do i mean by this uh we have a footage here of a of a person uh sort of picking up some objects and and kind of moving them to a different spot so if our task was to rotoscope this hand and we wanted to isolate it and create a mat you know one of the mistakes that beginners might make is kind of arbitrarily placing keyframes on your timeline so we have a timeline down here in the corner and sometimes people you think you just put a keyframe you know every 20 frames or every 30 frames or maybe shorter if it's a shorter shot but we have a lot of frames here but uh the problem with this is you end up kind of counter animating your uh shapes so if we were to look at the motion of this hand and what you want to do always before you start your footage is to watch the whole footage and try to identify some patterns in motion and there are usually some characteristics of motion that are mostly always the same unless you have really chaotic motion but there are some principles of motion that we're going to talk about briefly that is pretty much the same for most objects so uh if we just look at this in kind of player footage we can see that the hand is kind of going between actually three different locations so if we were to just put a key frame at the beginning and one at the very end we're actually going to miss one of the spots here so if i were to kind of draw it out on a just sort of a motion path here we can see we have like a starting location which is here uh we have like a top location and then we have sort of an end location like this and so if we were to just draw that out it's basically kind of a triangle so rather than just arbitrarily doing one at the start and one at the end what you want to do is i is place a keyframe at the the change of motion so where an object slows down and starts to change direction you want to look for those changes of direction and that's where you start your keyframes so basically you would just put a keyframe here at the beginning of your shot when the hand reaches the top that's another keyframe and then we would put one at the end and that would avoid us making the mistakes of having to counter animate stuff because if we put a keyframe at the beginning and one at the end um you know the roto shape will just slide between those two shapes like this and then we're gonna have to like kind of counter animate it to make sure it goes up and all those kind of things so you really want to watch the motion put your keyframes at the the key points of motion changes and angle changes and that will save you actually a lot of time then rather than just arbitrarily putting on random frames one other thing to note is that usually objects uh they kind of ease in and ease out so that's something to keep in mind so once you have your main motion points in place so if you put a keyframe here here and here um usually objects will kind of and this is a very chaotic motion they'll kind of ease in and ease out so basically it will kind of slow down here and it will start to speed up here so those would be another place you'd kind of put your secondary keyframes is just before the object kind of settles into its next position so if you look at the motion objects you know we you know objects will gain speed but they kind of have to gradually get that velocity and the same with decreasing so that's something to keep in mind when you're you're placing your keyframes uh look for the directions of motion make sure your ease in and ease out points are there as well and that's going to save you a bit of time tip number two is separate by objects so uh what this means is uh basically you don't want to rota objects together especially if they're on different uh planes of parallax uh or if they're deforming differently from each other so you can save yourself a lot of time by simply separating the objects by different shapes so if i go to the keyframe here we can see i've taken the foreground object and an object that's behind it and even even the area that you don't see the rest of the object you can overlap those uh two pieces and that's just gonna make it a little bit easier because you can simply just grab the entire shape as the shot is moving rather than if you were to roto it like this where the points are together maybe do a little bit of better job but you know if the points are together like this these points might slide along the surface so one of the things you want to do when you're rotowing is not only consider separate objects but also and this seems to sort of get looked over when your beginner potentially is like you think that the points don't matter kind of on where the edge it is and that's actually something that's really important because if you let your points slide around on your edge uh you think you're just trying to capture the silhouette of the shape but it's not the case you can get a little bit of a wobbly edge if you put too many keyframes or your uh you know your points are sliding around on the surface like this like if if the shape is kind of going along and this point doesn't stay in the same spot so what i do is i typically look for a feature uh you know if we see that the black line is here on the hat and i see that there's a point here i would try to keep that point as close as i can as this uh you know sequence goes on so that's something to keep in mind so keep objects separated keep the points relative to the place that they're originally placed and you're going to get a more solid roto by doing that so tip number three uh we have stabilize your footage and basically this is pretty straightforward but it's something to think about if you have shaky footage something like this if we take a look we can see this is sort of handheld let me just kind of zoom in here sort of handheld footage and pretty shaky and all over the place in terms of the motion and so if we wanted to rotoscope a few of these fruits or kind of things being carried in this basket here again we want to rotate the object separately maybe we want to isolate one or two of these we wouldn't want to do every single shape as one shape like the whole silhouette of this thing maybe we want to color correct those to be a different color so what we could do is uh take a tracker node and we'd want to stabilize it do a roto and basically match move it after so we would add a track uh we take a track and we try to find a feature um this is going to be a little bit trickier because uh the lighting is changing quite a bit if we if we look at the footage uh the lighting is changing quite a lot in there so you might have to do a little bit of manual uh 2d keyframing here but i'm not going to go and do a complete uh perfect track of this but just to show the example so i could set the reference frame where we are in the transform node and we can try to find a good feature also one thing we can sort of turn on in the settings here is adjust for luminance changes so that will help a little bit with the the changing of lighting i do expect that it'll probably go a little bit crazy but we'll see so i'm going to use the uh c and x key on my keyboard and i'll try to find a feature maybe i'll go on the front here because this one's a little bit more in the sunlight if i hit c uh it'll track forward so we can see it's it's popping off there so maybe it's not the best feature uh we'll see if we can find a different one maybe this one here on the corner we could try that we could expand our range a little bit and hit c so that one's working a little bit better so i can use that one and it's sticking relatively well and we can just adjust it as it goes off so c will track forward if i hit x uh it'll track backwards in time so i can go frame by frame and just make sure i get a couple good frames of this for the example um and it if it's not completely perfect you can you can always go in there adjust it of course this window really helps so pay attention to your sort of stabilized window here and just see if it's kind of jittering so uh if it updates properly which sometimes it kind of lags but this is a good way to see if it's jumping so these two frames are good but between here and here if it updates we can see it just hops to the to the right a little bit so we can just slightly adjust it over and then just keep doing that until you get a really good result so i like to make this window really big if you're trying to get a tight sort of track so i can kind of put it here and step back and forth and just check and try to get that sort of sub pixel accuracy if you can so that's how you can get really tight tracks as well so i was going to actually make a different tutorial just on that because it's very useful to know if you watch that sort of sub pixel motion um this window really helps so just keep stepping through and we can see it jumps off here again so we just slightly slightly shift it over and i think that's good enough for the example if it's a little bit off we can always fix it later but uh that's good enough what i'll do is i'll go here i'll export a match move baked i just like to do it baked just because it doesn't mess up if this thing gets uh kind of messed up here on accident so we have our match move and i'm going to also do a stabilized baked so we have the two of them uh let's get this stabilized baked so once it's stabilized once it's matched moves so we'll put the stabilizer on there we'll put a roto in between and then we'll put the match move sort of at the end and so uh remember our reference frame so a reference frame was 151 i believe uh that's our reference frame so i'm going to start my roto there i'm going to close all this stuff and we'll just roto maybe one of these we'll just kind of put a quick roto here so we can drag it out and i'll just drag it behind for now uh and i'll just kind of go like this so something like this i can select all the points hit z and smooth it out uh i use that quite a lot i like to work with the bezier curve some people prefer to work with the b-splines i just find it easier to have the control so i like to just select them and hit z to kind of smooth the corners and we have something like this and we can view it and this should stick a little bit closer so you see if we were to just roto on the normal footage the difference is quite large if i just step between the two frames but if i'm looking at the stabilized version if i step between those two frames you see it's already done most of the work for us and if we were to roto without the stabilize a bunch of these different ones we might be a little bit off in our track like one might go up a little bit another one might go a little bit differently and then you're gonna get all kinds of jittering so this is why uh stabilizing is really great because it's kind of getting the general motion for uh this large area and so if your camera is moving if it's panning you can stabilize that if if it's an object that's moving independently like this one you can stabilize that as well so just things to think about think about the motion and think about how you can get rid of it do your work and then reapply that motion back so once we've got our roto i'll just do another frame here we can always just adjust the lines as we need to just make sure it's like really tight and i'll just do like three frames here um and yeah so i think it's actually i think actually there so we're just not seeing it because it's in the shadow um so i like to step between my frames here and see does it feel like any point is kind of moving and if it is we want to make sure that it's not doing that so we can try to remove that sort of jump make those those those jumps very very small so something like this i think it's a little bit off still it's hard to tell with the light here that's changing so much but uh really it's easier to just kind of look at the the point so something like that is probably good enough uh for now and that's good enough and now we have an alpha so we have our alpha here um if we want to use this back on our main footage we reapply the motion with the transform match move and now if i watch those three frames it's going to move with the footage so the movie we're kind of reapplying that shakiness uh and we have all of that there and actually what we can even do is now that we've done this here um this uh transform stabilized we don't want to run you know the whole footage through stabilize because you're going to get a little bit of filtering it's going to blur your picture a little bit so you actually don't want to stabilize and do your work here we this is more just like a preview so once we're done with it we can kind of just unplug it and we actually have the roto here with the match move so you don't even stabilize doesn't do anything at this point we can just kind of disable it or or keep it there it doesn't really matter um and then what we can do is just use this as like a color grade so we can plug it in like this mask and then we could use that in whatever way we're trying to achieve here so we can you know change the color of this thing uh we could blur out blur out our alpha a little bit and just the basic stuff so we have that kind of sticking so that's something to think about stabilize your shots when you can if there's a lot of motion it's going to help and especially if there's a lot of objects um you know you can also do you know planar tracks you know if you have an arm that's sort of swinging or a character that's moving a certain way there's different you can use other types of tracks it's not just the the 1d track that we've done here so the next thing we want to think about are primary and secondary forms so when you're rotoscoping uh typically there are uh you know complex shapes that we can break down into uh smaller and simpler forms and so this is just a video uh we have this you know uh kind of rooster walking here and uh this is an example of this so uh we did talk about separating things by objects you know um easily identifiable objects you can you know like these leaves is very obvious which are separate but with complex forms that have overlapping shapes you can also do the same thing you can actually break them down into simpler simpler shapes so an example of this might be uh taking the body of this thing and we can sort of like we could do a roto uh of just you know maybe the general outline of the body and sometimes uh some of the smaller feathers uh might you know pop up independently so rather than doing that on the overall silhouette like adding to this main body shape like this we wouldn't want to just keep adding little shapes every time something pops up rather what you can do is simply create smaller forms and uh whenever those those uh small shapes break the main silhouette uh that that is a good way to do it because uh you'll kind of save yourself uh a little bit of work there so if i switch this to a different color we can see that so you see a primary form the the little bumps that create secondary forms and this is a pretty useful technique and you can as many of them as you need to depends on the the complexity of the the form that you're doing um you know for example this might be another example you know if you're doing this sort of uh uh tail thing here you could do maybe like the main one and then you could break the smaller ones off because they're gonna be they're gonna be moving pretty differently so you could break it up into as many forms as you need depending on the motion and of course you want to look at the motion uh beforehand as well so this is the same idea so we have the main body we can break that into two different shapes we could have the wing i'll just do a real quick uh sloppy one just for the example uh and we could just like make a different color um to see a little bit better so that would be another secondary form so you see uh it's not like one object is just one shape it's like we're breaking it into many different things and that's going to make it easier to animate because we can just you know we can rotate it and things like that the last one we have here is using rotational points and now that we know about you know primary and secondary forms this is sort of a similar concept but really just breaking those primary and secondary forms into uh their independent motion paths so most forms unless you have a really deformable object isn't going to change size that much so really if you can just separate your objects into sort of based on their pivots the general size of those independent shapes that you draw won't change that much so really you can kind of rotate them and just move them around rather than moving a bunch of points so if we're looking at this sort of this sort of dog kind of jumping here uh there's there's a lot of motion going on but the general you know volume isn't isn't deforming that much like the muscles and skin are stretching but obviously the bone structure is going to stay uh the same so uh what you want to do is separate this into you know many different shapes and just basically do it how it's kind of structured in the animal so you would kind of do uh you know this area first we could separate this into one shape we could separate it here like this and we could do another shape maybe for the ankle area like this and this is just a very very quick and quick and sloppy one but uh it'll get the idea across and then we can do another one on the bottom if we want so we could separate that into three shapes maybe you could do two shapes uh if if you want to do it that way but so as this kind of goes what's nice about this is if for example this bottom part rotates here we can just rotate that that form and just put it here and then kind of go like this same with this guy we can just take this and move it over and i'm trying to line up my points remember what i said earlier trying to keep the points in the same area so i'll try to find a point like the very corner of his uh sort of i guess this would be like the angle here uh finding that corner point and then trying to get that lined up and then trying to get the rest of the points following move them over and then hit z to smooth and that's good enough so you can see how it's a little bit helpful to just kind of separate into different shapes here we can have them overlap and it doesn't matter um and it helps us kind of keep our points uh more clean as well rather than having one shape with like tons and tons of points um so that's basically it uh yeah just keep that in mind if objects are rotating you know uh it's a really good opportunity to use different shapes because we do have this pivot point if you hold control you can put the pivot point on the rotation and we can just rotate and it will pivot around that point so a lot of real objects will rotate around a different center point and you can utilize that to save a little bit of time and that's basically it so that's five tips for beginners to increase your speed with roto

Channel: Compositing Academy

Views: 4,477

Keywords: nuke, rotoscoping, 2d tracking, stabilize, matchmove, alpha, channels, compositing, cg compositing, compositing tutorial

Id: rBPz0LL0yF0

Length: 19min 16sec (1156 seconds)

Published: Sun Mar 27 2022