How to Create the "Predator Effect" Using Distortion in Nuke

[Music] hey everyone welcome to Johnny how-to so in this video we're going to talk about the eye distort node which is a way that you can warp one image using the footage of another so for instance if you've ever seen the movie predator the old Arnold Schwarzenegger movie the predator kind of goes invisible and kind of cloaks himself against the background and blends in and so in this particular case we have some footage this is when the iPhones very first came out and the whole model for Apple was there's an app for that so those idea was there's an app to make him go invisible and we're gonna have him go invisible and kind of warp the imagery of this background jungle scene so there's a few things you need to do in order to get the itis tort note working correctly I'm going to walk you through that and also I'm going to talk about using the footage that we have here since it's been set up a particular way so let's go ahead and jump on in and we'll work through this alright so first off we have this footage it was originally on a green screen and you can see that obviously the green is gone he's been already distilled to take away the green and get the green spill off of his pixels himself but rendered as a separate file was a tiff sequence of just the cutout for his imagery and then the backgrounds clean as well so what we're going to do here is if I go and look at his footage Adams footage I press RGB and then a to look at the Alpha Channel you see there's no alpha channel here well there is it's just black meaning that it has no information in it that we that's useful to us if we view the Matt Channel RGB and then eh this doesn't have an alpha Channel either so this can be a little confusing is usually when you see a cut out you think of it as an alpha Channel or a cut out channel or a Matt channel it is or it can be used as that but it's not assigned to the Alpha channel yet so the first step we need to do in order to cut out Adams footage is to actually copy that over and the way we're gonna do that is with a copy notes I'm going to go and just click in the gray space here in the new graph press K for copy and you copy from the a input to the B input so I'm copying from here I'm gonna copy the cut out to his footage here and the defaults for the copy note is from the a and put your copy in the Alpha Channel and you're copying it to the Alpha Channel of the B input now again since we already checked we know that's not the case right now because there is no off channel for this footage right here so we need to change this copy down just a little bit so instead of from the a side to the B side the Alpha Channel I need a copy one of the other channels I'm gonna go on and look at these and it doesn't matter because they all have the same information whether it's red green or blue it's all just that black and white information so I'll just go and use red just because it's the first one and now you can see it's copying from the a.m. put the red Channel and it's copied into the Alpha Channel of the combined version here so if I go and view this RGB and then a we do have the cut out here and notice he's not cut out yet and that's because the copy node does not pre multiplier actually apply the cut out operation so in order for the cut out to actually take place I'm going to select my copy node press tab start to type the word pre mult which stands for pre multiplication press ENTER and now he's actually cut out and can we put it on a new background just becomes background we'll go ahead and put him on this jungle background here just so we can kind of see what we're dealing with so I select the promote mode press M for merge input for above B input for below or for background and I'll go ahead and put him above the background it's a little bit small in this particular scene so I'm going to go ahead and after the Primo transform node so I'll select the pre multi for transform and I'll go ahead and move him into general position just so we can see the effect a little bit more magnified I'm going to prime make him a little bit bigger than I would otherwise but this should Allah straight the idea pretty well okay so now we have him against the background press H to fill him to the viewer size here if we go and play back we see he is animate against the background doing his predator thing but he's not invisible yet in order to do that we need to use the I to start node and we need to set that up in a particular way so the I distort node itself relies on contrast of the imagery that's warping the background meaning that in this case it's going to be Adam that's going to be warping the background and you basically want as much contrast as you can get so you can differentiate between the dark areas and the light areas so if I press R for red I could see there's a good amount of contrast between his skin tones and his shirt and jeans and his hair is everything and everything green a little bit less blue probably the least it doesn't mean the blue or the green might not work well but at least for the most pop I'm going to go ahead and try and use red channel so in order to get everything to the red channel I'm going to use a shuffle note so click down in the gray here I'll type the word shuffle and select shuffle channel I'm going to go ahead and plug this into after I already have him transformed and cut out because I don't I want the size of him when he's warping the background to match the size that I have him on the background here so I want the warp version to match the version that has him just looking normal so off of the transformer I'm going to plug in my shuffle I'll just go and get a little room here I'm going to go ahead and name this our in the label here just so I know that I'm gonna shuffle everything to the red channel the way the shuffle node works is this is what you bring in and this is what you spit out so I'm bringing in the red channel and outputting it as the red Channel the green in is the green out as the green in is the blue out of the blue alpha and alpha don't want to adjust this I just checked the boxes so since the red Channel is why I'm interested in missing to say okay I want to shift everything to the red Channel and see his arm hair at least so if I click red for all these you can see that he has just that black and white version based on the red channel information if I change my channel r g b or a it all has the same look to it so now I know I have everything shuffle to the red Channel alright so from here I'm gonna go ahead and the Ida store node if I go in and add this real quick you can see it relies on something called U and V channels and these are channels that don't exist at this moment but basically it's going to distort it horizontally and distort it vertically in this case we're gonna use the same channel we're just gonna use the red channel information but we need to create that channel for the Ida start node to use and the way you do that is whatever you need to store it or where you want to distort it so I wanted to start the background so I'm gonna go ahead and plug it in to my background as a separate branch and right now you can see nothing's happening because well even if I pump up the UV scale nothing's happening because well it's not doesn't have anything to start with and remember it's looking for those UV channels in order to do the distorting and you can choose different channels but let's go ahead and do this Balian create the UV channels that it's expecting so in order to do this I'm gonna go ahead and create a shuffle copy node and I'll spit this out out on its own here I'll just plug in the one input when I'm copying from and now go ahead and hover over here I'm gonna say I'm gonna copy it to this background right here and actually do this as a separate branch just to make a little bit more simple and easy to understand I'll go ahead and call this UV creation alright so in this shuffle copy node and just think of this RGB a think of that as a pallet so if you guys know what a pallet is is something that you would store things on when you transport in a truck or a plane or whatever platform and then just imagine you're putting all kinds of paint buckets on top of that and in this particular one with regular imagery you have a paint bucket that's red a paint bucket it's green that's blue and then alpha which is kind of breaks the analogy but is kind of invisible ink I guess you could say basically what we want to do is we want to take the red channel information from the shuffle node and we want to take that information from the red channel from that palette that has the red and green information or whatever it is and put it on to a new pallet that's called distortion or or UV or whatever might be or to store it and have those U and V buckets filled with the red channel information so hopefully this will make sense as I go through so what I'm gonna do is I mean instead of RGB a being the output I'm gonna click on new and now I can create custom channels for mute to work with so you can name this anything you want but you probably want to name it something that's gonna make sense so I'm gonna go ahead and name this distort and I'll call this distort U and distort V now I can I already created this earlier that's why it automatically filled in the U and D there and it might not let me create it again actually because already been created let's go and click OK okay and so now you can see that I am inputting since I checked these boxes the red channel information from the one input and output in it to the U and the V on the again at least in this analogy the distort palette so now that that's done I can go ahead and connect my I distort node to this version that's coming from my background to the shuffle copy and now I can go ahead and distort my background and so if I go and double click on this I need to tell it what channels do I wanted to start well I want to distort the red green and blue pixels meaning the image of jungle and the channels that I want distort it using is the distort palette that I just created so I'll click to store it and now I want to have my UV scale you'll start to see that it's warping the imagery based on the luminance the black and white do we have in the red channel here so if I go and view this and I'll go ahead and pump this up more so the slider only goes up to a hundred remember if you hover in front of or to the side of any number and press up it's going to increment that number so if I go and up this to save you know a very very high number here well higher than I'd probably want to actually go and I go ahead and go fullscreen on this I'll press H to fill again and play this back when it's emotional oddities receive actually do have him animating against this background and kind of looks like his cloak again kind of like going back to that predator comparison of where it's almost like you're seeing through the person but it's still rippling the imagery behind it if I go in place back at regular speed doesn't look too too bad especially for such a simple effect and it renders really really fast as well so the one little last bit that Madea to make this look a little bit nicer is let's go ahead and have him go from looking normal on the background and as he starts to crouch down he goes invisible so it's like he is enabling the effect so right here is where he's starting to crouch down so around frame 34 35 so I'm going to go ahead and do a dissolve node which lets you blend between the zero input and blend over to the one input and so here I'll go ahead and just around frame 35 and the witch slider tells you which one you want to show do you want to show and make sure I'm doing this do you want to show the zero input which is him on the background or you want to show the one input that shows invisible you can see I can kind of toggle between so I'm gonna keyframe that so around the frame 34 33 I'll go ahead and keep set a keyframe so click on the curve and say set key and the witch is set to zero and I'll go ahead and as he's starting to slow down and is crouching down about right here I'll go and set the witch to 1 and you notice as I adjust the slider this is going to kind of change from this being lit up to this being lit up as far as the pipe so you can kind of see it blends over from one of the other and of course if I go to my dope sheet I can see there's two keyframes there for the dissolve node under the witch liar and I can see in my curve editor it's here as well so if I go in plates back let's go and click on play to go in invisible as he's crouching down I'll go and go fullscreen on that so we can see a little bit easier they have kind of this fun little effect to where it's kind of engaging there I wanted to have that be a little bit smoother in the animation like where it's easing into that I can go ahead and in my curve editor select this guy and kind of like eases and after facts of this case a okay have this kind of decelerate into position there and have it start to accelerate into the transition here and it gives you a little bit smoother a kind of an eased result so I'll go ahead again go back a little bit go fullscreen play this back you should be a little bit smoother this time around so it starts a little bit slow and then ends a little bit slow as well and that is the basics of the I distort node so if you imagine you can use this for all kinds of things so say you have water drops you want to have hitting a puddle but there wasn't really rain you can use some water drops that you recorded and go ahead and distort that footage or in a fountain or anything like that so when there's a heat coming off of a flame it kind of distorts the air around it the gas and everything so you can go ahead and use fire to give that kind of fire ripple above a really hot surface so a lot of really really cool ways you can use this and best part about it is you can use regular imagery you don't have to have any brazii 3d rendered imagery and it renders this is just distorting the imagery of one image using another image it renders very relatively fast so you can see here that and this is running off of my slower kind of network-attached device that this actually is rendering pretty darn fast and so it's a nice compromise instead of having to do a full 3d effect so hopefully this was helpful to you I'm sure you can see a lot of different ways you can use this the exact same kind of effect and setup inside of After Effects and fusion as well so this is not limited just nuke hope this was really helpful to you and I'll see you the next Johnny how to you

Channel: Johnny HowTo

Views: 3,817

Keywords: How to Create the Predator Effect, Using, Distortion, in, Nuke, johnny howto, cg, vfx, tutorial, how to, learning, filmmaking, step up, master, tips, idistort, predator, distortion, invisible, ripple, foundry, nuke

Id: FN7FBGi1f5w

Length: 14min 5sec (845 seconds)

Published: Mon Mar 09 2020