Advanced Sky Replacement Tutorial | After Effects

hey everyone sam here with a quick after effects tutorial for you guys and today i'm going to be showing you how to do an advanced sky replacement so this is what we're going to be creating [Music] now when i say advanced i'm actually referring to the range of different shots you can use this technique on rather than the actual difficulty of the process and i'll get into that more in a second but what that means is that you can apply this technique very quickly to many different types of shots and it'll still work so here's our original shot and then here's what we're going to be creating and you know if i zoom in here you can see we have a lot of detail in this mat still and if i show you the original you're really losing just about no detail on these trees and these are pretty complex shapes so this is a really good technique and i'll show you guys some more examples here and then we'll get into it so a lot of tutorials on youtube and elsewhere will use the luma key effect or they'll use key light or color key if the sky is blue but that leaves you with a range of problems first if you don't have a blue sky so if there's clouds or anything you can't use the color key effects so those are already eliminated second if you have elements in your foreground that have a similar exposure to your sky you're going to lose them as i'm demonstrating here with this luma key effect so if i zoom in here on his face and we just apply this luma key that's about as good as i could get it obviously we're getting a very dirty mat here but we are also losing his forehead if i show you uh the technique that we're going to use today you can see now we're not losing his forehead and we're also getting some really nice detail in the background so third if you have a shot that has objects that are both in focus and out of focus as you can see in this shot you run into a whole world of pain because you essentially have to choose which objects to refine your mat around the blurred ones or the infocus ones and you can see here we have these really blurry trees in the background and we also have this really sharp line on his hair and we want to keep all that detail in his hair but we also if i go up to full res here we also want to preserve those nice blurred edges in the background and as you can see we're really losing no detail here on his hair if i take all the effects off of this you can see the original shot and that's what we end up with so we're getting a lot of detail which is what we want and obviously as you can see the fourth thing here is trees so anything with a lot of detail like trees pattern windows power lines you're going to lose all those things in your mat if you use any of these other techniques like the luma key or key light or color key effects whereas here we're preserving all this detail and we get this nice fall off between the blurred lines and the background that we're keying out so so the technique i have for you today is going to solve all those issues and it's going to give you a lot of flexibility to get the look you're after so this is the footage that we're going to be working with today and the first thing that we want to do to get started here is search the extract effect okay so you're going to see it under keying and we'll take that and drop it onto the footage here the only other layer i have here is the null which is the tracking data which we're not going to be using until later so when you apply this to your footage nothing is going to happen and that's because we'll need to move this point slider to the right now before we get into moving this slider around um i want to change this to blue okay so the channel that we're going to be extracting the alpha from is the blue channel and that's going to work a little better for us for this sky because obviously we have a blue sky now if you don't have a blue sky you're going to want to extract from the luminance channel which just refers to the brightness of the image essentially and generally your sky is going to be brighter than the rest of your image for the most part so usually if you pull the alpha from the luminance channel you're going to get a pretty decent result so i'm going to do blue and that's because the blue channel is going to give a greater difference between the subject and the sky so we're going to invert this and we're going to drag this to the right and you're going to notice something similar to the luma key effect happening where we're getting rid of the sky and now the beauty of this effect is the fact that we're able to create a nice fall off between the areas that are kept and the areas that we want to remove and we do this by taking the second point slider and we're going to move it to the left and what that's going to do is create a nice soft fall off between the alpha matte we're creating and the removed parts of the image and as you can see this gives us a much nicer effect where we don't have such harsh lines and we can keep all the details in the edges so if you look at these trees here i'm going to go up to full res so you can see a little better now we're starting to get those details and those blurred trees in the background are starting to look a little better so you can play around with this you can keep a little more remove a little more i generally like to leave a little bit of the original sky in there i find that helps it to blend a little better already we have really good detail in the trees and also we're keeping all the detail around him as well and you're just not going to be able to get that level of detail with any of the other effects that i've mentioned before and what you'll notice is that you know in the foreground like i said before we have this nice sharp edge around him because he's in focus but we still have these nice blurred lines in the background uh which is what we want and that's because we've used this bottom point on this effect where we can kind of tweak the softness of the fall off when there needs to be softness and it still maintains the sharpness when there needs to be sharpness now the next step is going to be using an effect called a key cleaner and that's just going to clean up our mat a little bit for us it's a bit of a slow effect so i wouldn't recommend leaving it on while you're working but as you can see it just kind of does a nice job of cleaning up these edges here especially the blurred ones just makes them a little softer and it also kind of just makes sure that we're maintaining as much detail in in his hair as possible and things like that what you can notice is that we're getting a lot of blue here on these trees so if you don't want to have a blue sky or you want to have flexibility to use a different uh color of sky what you can do is use the hue and saturation effect and go to the channel control for cyan and we're just going to reduce the cyan saturation so now we've just kind of reduced some of the blue spill you can take it down even more if you'd like but here's the difference so that's going to help us later when we're compositing this shot so that's about it in terms of the sky removal and you can see that we have a great level of detail in our mat and now we can move into the actual compositing so i've already motion tracked the shot which you can learn to do in the beginning of this video here that i'm going to show on the screen and i can also make an in-depth camera tracking tutorial if you guys would like so now all we have to do is put in our background sky that we want to replace with and as you can see we have our little you know apocalyptic city or whatever you want to put in there you know you can pretty much put in whatever you want just you're going to have to match it with the background so you know you can put put this bridge in or whatever and you just want to make sure that you blend it properly so i'll show you quickly how to do that so as you can see we have some holes here and we're going to want to fill that in and what i'm going to do to do that is i'm just i've duplicated this footage layer and i've moved it down here okay and i then created a solid which i made a mask on and i parented that solid to the null object so now this mask follows around the horizon throughout the shot so what we're going to do then is go to the mask settings we're going to turn up the expansion and we're also going to turn up the feathering really high and what that'll do is when we turn this layer on you can see that since we put it below this top layer of footage it now fills in all those holes and since we feathered it it kind of creates this nice little horizon haze for us and we want that because that's a realistic effect that we see in the real world so we're just kind of using this background footage to our advantage and it's also going to allow these trees to blend in a little better with the background so what we can do now is uh what i also like to do sometimes is add this gray solid and it's just a square and i feathered it quite a bit and you can see it's just adding a little more background haze and i put it below all the footage layers and then you know we have our apocalyptic city which is just this photo and i've just put it in here behind all of these layers and you know we're going to want to parent everything to the tracking null you know i've added a couple a couple smoke layers here as you can see and you know there we have we have our shot so some very basic compositing techniques here um but it's going to give you some really nice results and as you can see this mat is super clean so and what's great about this this was a really difficult shot because we have trees we have out of focus elements and we also have sharp elements so that's the hardest thing to do when you're trying to pull a mat from something so as you can see this is going to work in a variety of circumstances if you have a solid mat it's going to work really well but you can see we got a really good clean mat out of this with almost no effort and very little time commitment so if you guys like this video please hit the like button it really helps to grow my channel and it means a lot to me also don't forget to subscribe for more videos like this in the future i'll be posting consistently every week and bringing you some fresh filmmaking and vfx techniques and tricks so you don't want to miss out on that so thanks for watching and i hope you guys find this tutorial helpful

Channel: Boundless Entertainment

Views: 36,773

Keywords: adobe, after, effects, adobe after effects, tutorial, adobe after effects tutorial, action, essentials, action essentials 2, video, copilot, video copilot, eisenhower57, vfx, rebel, sky replacement, beginner, advanced sky replacement, advanced, advanced sky replacement tutorial, how to, how to remove sky, removal, sky, luma key, chroma key, keylight, keylight tutorial, basic

Id: MDmMjJZ6vZc

Length: 9min 23sec (563 seconds)

Published: Wed Jul 28 2021