Nuke Tutorial - Make It Rain

hi guys professor Paul here and it's been a while since I've done a new tutorial trying a little different format now trying to make more tutorials as a priority I've been really busy I've been making a lot of visual effects doing a lot of cool stuff and now it's the time for me to start sharing it with you today we're gonna work on this shot over here let me pull this up we're gonna be working on this shot over here where we are going to be turning a shot that was that was filmed in dry conditions into a rain shot this is for the interactive horror film help Falls that we worked on a little while ago and the you might ask yourself like okay why why did they take a visual effects approach to this why not just film it when it was raining well it's one of these things where they did actually film in the rain and they actually filmed this this sequence in two separate passes one time when it was raining at one time when it wasn't and it being a low-budget film they didn't have the opportunity to go back and really film stuff that they had already put in the can so when they filmed this rainy sequence they decided well this is really the look that we're going for for the film so let's take this other footage that we captured on another day and let's turn that into into a rainy scene as well so you can see this was already a visual effect shot because we were replacing the sign and doing that weird little sign degradation on it so I'm gonna pause this before you get to any spoilers but you can see you know they really really liked the rain look and and at the same time they didn't want to reshoot this shot so it was up to visual effects to try and make them consistent make them match and and all of that so I'm gonna just do a kind of a quick version of how this all works and we're gonna look at this nuke script that I've got that is the full shot you can see it's broken down into separate sections I like to use these backdrop nodes when I'm doing a complex shot like this so I've got this section that's just dealing with the reflection on the road then I've got this section that is dealing with the mist on the car or the mists being kicked up by the cars tires and then this was the the original shot was just this when when all we were doing was the sign replacement it was just this section and then finally we have the the raindrops falling and our right node so that's the the whole scene where we really need to start is when we take when we tackle a scene like this we have to figure out what the best procedure is gonna be and so I started by just looking at okay how can I really do this I knew I needed to reflect the trees and the sky on the road so you know natural inclination might be let's throw the mirror node on there and just flip it vertically and I'll merge that back over the original as a screen let's just let's just take a look at and see what it see what it looks like and right away it's got some problems put it but it is giving me kind of an idea of what the what the look should be in terms of what's reflected on the road and how it's gonna how it's all gonna work the problem with it obviously you know we've got this weird angle situation we've also got the reflection of the car above the car itself rather than below it and then we've got this mirroring happening in terms of the tilt right because I've mirrored on the vertical axis now the tilt you know where the original shot is is tilting slightly up the reflection is now tilting down which means the two the two things are now not using the same camera move so I need to in order for this to work I need to get rid of the camera move on the reflection and put the camera move back onto it so so essentially remove the camera move mirror the image put the camera move back onto it so that gets a little complicated for me when I look at this I think okay this is a 3d shot has to be 3d tracked because even though the it's just a simple pan and I probably could tackle it with a a planar tracker you know a planar tracking the road even though I could probably do that that way I have the car crossing through the area that I'd like to track so that's gonna be problematic and my effect is gonna have to extend in z space into the background so to me this just really felt like it needed to be a 3d camera solve in order to to get it to work right so when I start to build a camera solve my first thing is I want to get rid of I want to get rid of whatever green is there in the original shot I'll do that by picking a neutral spot you know a fairly even spot and I'll put the denoiser on although lately I've been using the neat video plug-in just because you take less of a performance hit if you just process the footage through neat render it out and then and then use that as your you're tracking plate but in this case just to keep it all inside new gex I'm gonna just use the denoiser and I'll usually look at my three different channels red green and blue and kind of look at what the situation is in each of them see how the D noiser is doing on each of them see if it's doing an adequate job I'm not really super concerned about image quality here because I'm not going to be using the D noise or the d newest plate as any sort of a component in my shot I'm really just using this to to create elements to do my tracking to create my reflection element which will be re grained later but I'm not gonna degrade it and then use the use the D grain version as the plate for my shot I that I cannot stress this enough that is just no no okay when you're working in Nuuk you should be working with the original plate as much as possible you should be retaining original grain as much as possible so don't think that because I threw a D noise note on this shot that then this is gonna carry downstream this is only going to be in the 3d tracking section of my script okay if I go back to my real script you can see that this D noise happens way off of the main the B the B stream okay this this is the main composite stream this D noise is only happening to feed this little cluster of nodes that are being used for the 3d track okay so let's talk about what these are why I have this blur that's merged - this grade this shuffle and then a roto before I even get to the camera tracker okay so a couple of things one I really need the road texture to be a big part of my track and right now the road texture is super smooth and isn't going to lend itself to tracking very well so what I like to do is kind of this quick and dirty high pass I'll throw a blur on there and a merge and you can set this merge to minus or difference and if you turn up the blur what you're doing is you're essentially extracting color information and leaving just texture behind right so I'm taking this this blurred version and I'm differencing it from that version which just gives me texture so I get a lot more texture in the ground and you know I usually go somewhere from 20 upwards depending on the shot you know you can see like I get a lot of texture when I hit about this 60-ish area so I'm just leave it there I usually will also grade this up I'll sometimes go as high as you know 10 or 20 because now I really just want to give the tracker a ton of stuff to lock on to and that's what this does for me is it kind of it brings out all the texture and anytime I have a problematic track a track that is just not working or something that's really complicated I'm gonna do this procedure just says standard operating procedure okay the other thing I'm gonna do is nukes tracker really wants you to remove moving objects right so I'll garbage matte this and a garbage man off the sky so let's go back over here to buy my real version of the shot and let's look through here alright so you can see I've blurred I've merged - I've gained I throw on this shuffle node usually just to make the alpha black just to make sure that I don't have any alpha components coming in from the original plate you know if the if the plate has an alpha or doesn't have an alpha or somehow upstream I end up doing some roto or something later in the comp I just don't want to pass that alpha down into here because what I want is I want this roto to completely dominate the Alpha leading into the camera tracker okay so so what am i doing here I'm one I'm just doing a quick garbage man on the car and it's shadow and - I'm I've just got a just got a really simple rectangular mat up top so that the tracker will just ignore the tree line on the sky and that's because the the trees are slightly blowing and also any texture that might come through in the sky you know from clouds and stuff those points are really hard for the tracker to figure out their true accurate distance and so therefore it can mess with the calculations you know if it's tracking a point in the sky it's gonna be really hard for it to know whether it's you know it's in the near plane or if it's in the far plane simply because there's just a lack of detail and context in there so removing the sky almost entirely from your 3d track is is usually desirable so that's what I'm feeding into my camera tracker and my camera tracker is set to use the source alpha as the mask so the source pipe here coming off of that roto is bringing that alpha with it so I'm telling you just ignore that source alpha I usually don't change anything in here just leave free camera no lens the story I just leave all of this but I'm not going to I'm not gonna deal with that in this there's plenty of 3d tracking tutorials out there that will go into a lot more detail on the 3d tracker this is not meant to really teach you the 3d tracker this is meant to kind of teach you the workflow on a shot like this I will usually crank the number of features up it defaults to 150 I find that that 150 is totally inadequate and when you are dealing with a with a shot that is ultra HD like this right at 3840 by 2160 you need a lot more points you need a lot more trackers so trial and error ended up cranking this up to 750 and lowering the feature separation my my general rule is as I go up in number of features I will go down in feature separation so if I've multiplied the number of features by you know by four then I've divided the future separation by four etc so I ended up with 750 and two as my my options and then I tracked it and I got a nice cloud of feature tracks that give me a good picture of the scene from there I will usually you know pick a handful right click and choose you know pick a handful of green ones right click and choose create card which gives me a little piece of proxy geometry and if I look through this turn this one off I usually will attach a grid to it and also let me grab the background pipe there we go so I usually get you know a little a little card that kind of stands in for the road and you can see I've kind of scaled it down on on the X and scaled it up on the Y and it's also rotated so that it seems to be the correct attitude for the for the road if you want you can look at the the point cloud although this point cloud is pretty lame it doesn't really do anything for me so I end up usually just kind of eyeballing it right so I can kind of walk you through that let me kill this card go back through here create card plug that in I usually just plug in just a standard grid operator and you can see it's usually the card is usually all out of whack so I will most of the time just go ahead and set all of my rotations to zero so that it now is zeroed out and then I can start to think about what's really happening okay so it's probably rotated you know minus 90 on the ax that's a good start right that's that's the ground plane so I can kind of start to rotate this and look at how do these lines line up sort of scale up on whatever axis makes sense and I can start positioning this you know I usually hop back and forth between 2d and 3d you can also set up you can set up a new comp viewer and peel it off to the side so now I can work in 3d while also seeing the result in 2d and I'll sit there and just kind of fiddle with this until I get it right and usually you know I'm doing that numerically but the idea is that I want to try to mimic the angle of the road as much as I can try and get these lines to line up usually do a fair bit of trial and error at this stage just kind of getting it into shape I might nudge it this way just a little bit and shrink it down so I'll do a bunch of tests in just in the viewport test renders in the viewport to see what's what kind of get my get my bearings see how it all lines up and then eventually once I've got that dealt with and I have to figure out what's actually gonna go on to that card and you can see it is this reflection so how did I get there well for one thing remember like I said I need to take away the camera move so what I ended up doing was I just picked a still frame just a single still frame I used the first frame in this case kind of arbitrary but I wanted to use a frame where the car wasn't visible and you know first frames just seemed to make sense and again mirrored it flipped it over and then transformed it because I'm trying to make sure that the tree line that the road isn't reflecting itself so if I were to look at the two side-by-side you know I'm trying to make sure if I just mirror it you can see the road would be reflecting itself but by mirroring and transforming I'm able to make sure that the the reflection is is entirely sky and trees not the road okay no yeah I could have used a corner pin to maybe pull this corner down and and try and keep the the grass you know lined up with the grass but I didn't feel that that was necessary for this shot you know it's kind of a personal choice and also you know depending on the shot but but basically you're gonna take this first frame and manipulate it until it essentially represents the reflection that you want on the road okay and once you've done that you're then gonna project it using a project 3d node and what I'm doing here is I've got a do head of the camera and that duplicate if I plug it into my scene that duplicate camera is going to you can see how I have two cameras in there so what's happening is you've got a camera that's moving and then I've told it okay at this particular frame stay there okay so now we've got a frozen camera duplicated and the other camera continues to move but now this one is going to become a projector it's gonna project the image and it's important that this projected camera is sitting at the same frame as the one you've frozen right so I froze frame one and now I freeze the camera at frame one and that becomes my projector all right so that's what's happening here is that now that camera is projecting onto this card okay it's projecting onto this card that frame okay it looks really crazy and weird in this 3d view but when I look at it through my camera view I now have this reflection that is going to stick to the road move correctly with the camera okay and and basically do what I want in terms of reflecting the sky in the trees on that road surface okay so that's that's good now you'll notice I don't have the car right the car is not there and that's because wanna frozen this frame and - we saw in my other example where I just did a simple mirror that the car we couldn't get the car in the road - both line up okay there's a there's this weird situation happening where you know the reflected Ray's coming off of the tree are hitting the road and bouncing back at the camera and they're artists they're at a different angle than the that same the same moment you know the light bouncing off the car emitting from the car bouncing off the road hitting the camera right the angles are different so what I need to do is rebuild the reflection essentially from the perspective of the road and the perspective of the camera by separating the car out entirely so to do that that just requires some roto and that just no two ways about this I mean you could plane or track this probably I believe I ended up keyframing this road oh by hand simply because the car changed shape a bit too much and the planar track that I tried kind of got away from it as the car got smaller and smaller and smaller you know just a simple roto and then a little bit of a grade and pre malt and then this bit here where I've flipped it and again I'm going to compare us to the original plate okay close this roto but basically what I've done is with this transform I've scaled it and I've done a little bit of rotation and a little bit of key framing so that it will kind of stay pinned to the bottom of the car and because my reflection is going to be distorted by the the rain I'm not super worried about making this totally accurate in fact I kind of like that it it wavers a little bit to me it mimics the irregularity of the road surface so I didn't get really specific and precise about the key framing you know I'm just trying to sketch this thing in there because without they were the car reflection this whole thing falls apart looks totally fake which I will show you all right so now you've seen that let me turn off my wipe and let's look at let's look at a frame and let me turn off the car reflection you can see it looks really quite ridiculous that the car is sitting here not being reflected so just having that little extra bit underneath that and merged on top of our projected reflection goes a long way and it looks really weird it looks really really weird right now right it doesn't look like anything like what you want but that's because we haven't we haven't finished processing this okay the next thing I would do and that you know having the the real footage of this same car on wet roads having that as a reference really really helped helped me to make sure I match the reflection right so I did a little bit of grading and a little bit of saturation to the saturation down some you know just some really simple raise the blacks lower the gamma lower the saturation that's that's going a long way the next thing is you might have noticed that there was that distortion on it and I did that simply by just creating a noise node with a little bit of animation on it all right so I'm animating the Z the Z attribute crank the gain up so get this real kind of crunchy crispy noise that I'm using I'm feeding that in with a copy node you can also do this with a shuffle copy node but essentially what I'm doing is I'm reading I'm feeding the the red and green channels which are just black and white images I'm feeding those into the forward UV Channel and then I've got an Ida stort node which is then going to use forward with a UV scale of 10 you know if I crank this up you can really see the the effect I wasn't going for a really in your face kind of kind of ripple to store it I just wanted it to be subtly distorting also throw a little bit of blur on there and that gives you your base reflection and then you'll see that there is this another copy node and a pre multi get to that in a second but you can see now the reflection looks looks good and watery it's lifted it's it's degraded it did you know it doesn't look like a mirror now it looks like a wet reflection on the road and if I were to simply plug that in by itself without that awful you can see it's it looks pretty good it looks pretty good I'm doing I'm using an over and it looks alright it's not great but it's getting there the the car reflection is sticking where it's supposed to obviously the reflection is hanging off the edge which we'll deal with and obviously it's over on top of the car which is what this this roto node is doing for me so yeah now I've got a roto node that is the car plus the car shadow and when I plug that in as a mask on this merge you can see it's now sucking the reflection underneath the car which is which is good all right but we have to deal with this other part here this the overhang and for that I built another 3d scene same camera okay same card but now what I've got coming into it is this noise pattern right which is just gonna be just gonna break up the reflection so it's not so glassy right so I've got a a reflection that is a little more one more natural little foggy and on top of it I have added a constant with some rotopaint nodes and those rotopaint nodes are the tire tracks and those are just simply animated by hand just painted them in so that they would follow the car okay and when we look at it through the projection we can see this I'm actually gonna look at the Alpha side because I've got a roto on it to limit it to the to the road surface right so now what I've got is this is going to be an alpha that is going to break up the reflection and also create the tire tracks in the road that will fade as the rain continues to come down and wets that area right the idea being with the the tires pick up the rain and some you have near nearly dry asphalt underneath and that nearly dry asphalt is not as reflective so basically where this is white it's gonna be really reflective where it's black gonna be very very little reflection and when I copy that in it now becomes the Alpha of my reflection and when I pre multiplication down so it is just sitting on the road and when I merge it over it is now only on the road and as the car rolls through it creates these tire tracks behind it okay from there the car mist is just this really really simple particle system okay you've got a sphere that I animated give us a second because it does take a little while particles are always a drag on your system but basically I have taken this sphere and I've animated it to follow the car and the way I did that was I actually was looking at this right so I I i had already I can't remember which order I did this in one or the other I basically was using because I had I had in 3d space you know the road and I knew exactly where the car was I either animated this sphere first and then painted the tire tracks to follow it or vice versa I can't remember either one it would be a valid way to do it and again you'd probably end up with two to view viewers you know one that is going to be looking through the original and you'd probably plug this in somehow yeah I'm just gonna disconnect these particles just to speed this up right so let's do that and you know I can actually see the sphere in my frame and so I'm kind of animating this moving it in on Z and a little bit on X&Y to follow the road and follow the car and I'm kind of you know roughly following the tail of the car this is because it's a particle emitter it doesn't have to be super accurate you know I try usually when I'm doing someone like this I'm going to try and get myself kind of like roughly there and not super concerned about being accurate at first I get it in there a keyframe it I'll add the particle emitter or see if if it's working and then see if I need to adjust it with this I'm just trying to make you know this spray of mist coming off the tires doesn't have to be super accurate doesn't have to be you know dead-on to the tires I'm not doing a full physical simulation of the tires on the road I'm just approximating it because it goes by so fast that all I care about is do I get this little bit of spray and it's really really subtle in the final shot anyway I'm not really concerned about making it dead-on accurate so I I believe that's what I did when I did this shot this is a couple years ago that I did this shot but I believe I animated this this sphere to follow the car and then went back and painted the in the rotopaint note painted those tire tracks to follow my my sphere but now the sphere is being used as a particle emitter and the particles are emitting and I'm using that shape I've just drawn a little bit of roto and blurred it just kind of create a little very very soft feathered particle sprite and that's coming through the particle emitter with a little bit of turbulence and so now that gets me that right gets me this little spray of particles and it doesn't really look like anything because particles in Nuuk generally look terrible until you go and put a bunch of stuff on them like blurs and grades and glows and things like that and like I said particles just take bloody forever you know the particle system in Nuuk is not great in fact lately I've been using Stardust in after-effects a lot it bounced back in for between nuke and after-effects a lot of times if I if I were doing this shot now I would do my particle passes and start us render them out and then comp them in in nuke so so that the and that's that's what I would do what in this particular case I just wanted to keep the entire shot in nuke so now you can see with the blur and the grade turned on I've got this very very soft very soft mist coming off the back of the car really really simple I'm not gonna get into the sign that was just a simple corn pin you know to make that happen but basically you know put the sign in there you know there's plenty of plenty tutorials out there for doing signs and if you want to see this I can do this but I'll do it on a more a more recent scene than this one and then the last bit would be the the falling rain and nuke has a preset particle system called the called P underscore snow/rain so yeah it's got this particle snow rain effect I'm using the same camera that I solved before and we'll see what this does yeah this is really really slow because it is generating a lot of particles yeah but you can see the particles are actually raindrop shaped and again I'm using a rotopaint node to make that little shape and a blur and that's what's being emitted through the the snow rain box I've also got a card where the sign is that I was able to derive from the tracking data that I already had but basically that sign is just there with a black constant fed onto it so that it creates this holdout so that I've got rain falling behind the sign and rain falling in front of the sign a little blur and grade on that screen it on top and it's really really subtle particularly when we are in proxy mode as I am right now for the sake of speed but at full res and full motion you can see the raindrops falling particularly in front of the tree area and that is basically that you know so you end up with kind of that that script right fairly complex but you break it down to sections right you deal with each piece at a time you deal with the road reflection you deal with the car mist you deal with a sign you deal with the rain and you try to replicate or reuse attributes reuse material that you created for each pass so that you're not starting from scratch so everything you can see all these expression arrows connecting all these cameras that that are all exactly the same I've got one two three four five cameras in here that are all doing exactly the same thing so every layer that is using a 3d node a 3d scene and scanline renderer set up every one of them is using exactly the same information so that I end up with all of these different layers that that just work together that stick together and and create the shot so that's kind of how I approached this shot you know I take a very modular approach I try and break it down into its separate components and I look at reference you know look at real footage as much as you can you may not be doing a shot like this where you have to match it to other shots in the sequence and everything needs to be exactly the same you may just be asked you know just add rain to this shot well look at real rain footage don't just invent what it looks like look at real rain footage you know there's tons of stuff on YouTube this tons of stock footage out there look at you know car driving in the rain in you know put that into a into an image search and look at it look look at what's happening look at how its behaving so that you are trying to reproduce reality instead of just coming up with what this looks like from your from your own mind oh if there's questions about this this is uh this is my tablet glove I use my Wacom tablet a lot and it just keeps your hand from sticking on the tablet my tablet is is pretty well worn I've had it for a number of years and you can see the this wear pattern so it's it's not as frictionless as it once was my hand tends to stick to it so so the little goofy little two finger glove helps a lot okay so I hope you guys enjoyed this I'm gonna be trying to do a lot more of these and if you if you liked what you saw here make sure you click like make sure you subscribe send me comments ask me questions if something I did here is in your opinion totally half-assed and there's a faster better easier way to do it I want to learn so tell me I'm eager to hear for you guys if there's things that I'm not seeing or things that I am not that I just don't know okay so share them please and I've got a patreon that I'm watching so look for information about that should be down below in the in the video description and I look forward to bringing you more regular content this is Professor Paul signing off

Channel: Foxtrot X-Ray founded by Paul DeNigris

Views: 75,484

Keywords: tutorial, visual effects, vfx, the foundry, nuke, nukex

Id: NKEFwG2bQlM

Length: 36min 13sec (2173 seconds)

Published: Tue May 14 2019