How To Replace Your Sky In After Effects


Sky replacements are incredibly powerful.  It allows you to either create an impossible world or simply enhance your visuals so that they reach that next level of quality.  Today for our example, we’re going to be sticking with a classic realistic sky replacement.  So open up After Effects, and lets work on saving our sky together.

Replacing Your Sky in After Effects!


This text has been transcribed and optimized for your reading.

So here we are inside of after effects, and what we have here is a typical scene where we have our subject and a sky that looks a little underwhelming.  There’s 2 basic scenarios you’ll tend to see when it comes to working with a sky.  You can have what we have which is just something you want to spruce up a little, and then there’s a sky that’s completely blown out.  Both of these situations can have multiple different approaches, but today we’re going to go over that first option and show you how to tackle it.

The first thing is to drop your footage into a new composition.  If you’re only using a portion of the clip in your final project, it’s a good idea to trim it down already, as you’re going to be working with effects that analyze the entirety of your clip that’s in your composition.  

You can also trim your comp to your work area to make things a little easier to manage.

So here’s where we start.  Just a normal shot with a plain sky.  The first step is to track your scene.  The reason we do this is because we need to tell our fake sky later how to react and move around so that it looks like it’s actually there.  Our scene isn’t on a tripod, it’s handheld, so it would look weird if the sky was still and the rest of the scene was moving.

To track our footage, we need to highlight it and then go down to the tracker here.  If your tracker isn’t here, then go to window, and select tracker.  Now go to track camera and the process begins.  I’d suggest choosing detailed analysis to give your track the best chance of getting the result you want.  It may take a while depending on the length and quality of your video clip.  But once it’s done, you should see all these tracking points around your footage.  Choose tracking points on objects that aren't moving, and if you can, chose them on objects that are further away.  

So the way that we select our track is by clicking and dragging a circle around the tracking points that you want.   If you’re having trouble selecting these markers, check to see if your layer controls are selected by going to view > show layer controls.

Once you’ve highlight them and when you right click you have a few options.  The traditional method is to choose a null and camera but I prefer to use a solid and camera.  When you choose that, you should see a solid pop up, and depending on it’s size, you might need to play around with it to actually see how it interacts with your environment.  We’re pretending that it’s in the distance so let’s see how it reacts compared to some of the clouds over here.

It’s pretty good, and we can see that it passes our big test where the camera pans over.  So for the time being this is really good.  The next step is to bring in our image of the sky we want to replace this with.  For me, I got an image from a site called unsplash which has royalty free images that have been generously donated by creators.  

I chose this image because I like how the clouds look and they’re similar to the few that are already in my shot.  Now that we have our shot of our new sky, drop it in beneath your original footage.  For the time being we’re also going to lower the opacity of our original footage so we can see both at the same time.  

From here, select the 3D option for your clouds and then pick whip this clouds layer to our tracking solid here.  Now what you should see is that it’s sticking to our footage and looks like it’s following the camera motion.  Perfect.

Here’s the last key part before we move to the next bit.  You can increase the scale and position of this clip without losing its proper tracking.  If you hold shift while dragging here you can scale up proportionally and not stretch out your image.  You can also select the shortcut key W to choose your rotation tool so you can orient your clip the correct way.

Make sure that you can go through the whole clip without the edge coming into frame.  And now this is what we have.  It’s looking great for right now, but let’s get really specific now.  We’re now going to deselect the sky and have our new sky showing through for only that portion of the clip.  There’s a lot of ways you could go about doing this, but we’re going to do this a special way.  Raise your clip transparency again to 100.  Now search for the effect, color range and drop it onto your footage.

Start by selecting this initial eyedropper selection and choose a very average part of your sky.  Now select the addition dropper and continue until your sky is completely selected.  If it helps you can hide your clouds layer by deselecting it here.  You’re definitely going to get some spill, so try to minimize it by using the sliders at the bottom of the effect here to finesse it to the look you want.  Using fuzziness can also help to prevent pixelation and flickering due to the effect.

Keep in mind that in a real horizon, you will get some natural fall-off where the sky meets the landscape, so your mask may not have to be completely perfect here depending on the footage you’re working with.

So right now if we turn on our clouds layer again we can see that the effect is starting to come together but it’s really bad at the moment.  But don’t worry, our cleanup job is actually going to be pretty simple.  

To start, let’s choose the cloud layer and create a mask that dips into the mountains here.  Give it a wide amount of room  outside of your frame.  

Great, now the bottom is separated out pretty well.  Next, go into your mask properties in the drop down and raise the mask feather a lot.  You should start to see it creep into the horizon a bit and that’s okay that’s good.  But it still looks bad overall.  Here’s where a big trick comes into it. We’re going to duplicate our footage layer, move it down to the bottom and then remove the color selection effect.

Now all the areas that didn’t key out properly are either covered by the new sky layer or by the backup footage layer.  This step is crucial.

So lets take a look at what we have so far.  That actually is starting to look awesome! We still have some cleanup to do but we’ve already brought it to a level where it’s somewhat believable.  

Next we can see that there’s some areas that got keyed out here at the top of the mountains.  Normaly mountains don’t have a sky blue top so we’re going to move the mask from our cloud layer closer up to the edge here and adjust our mask feather even more.

Lastly, color correction.  We need people to believe that these two elements actually belong in the same world.  So you can either adjust the new element to mach the footage, change the footage to match the new element, or some combination in between.  To start im going to adjust the new element to match our footage.  

These clouds are a little too dark up here, everything else is reallly white so lets do a simple lumetri color adjustment and start to make our cloud scene brighter

We’re also going to make it a little bit warmer as the blue in the sky is really really intense.  

And guys, there we have it, we’ve replaced our sky to make our entire scene feel more amazing!  Try this out for yourself with different scenes.  Try to make it realistic, or try to make it surreal.

We hope you found this video helpful.  If you did, we’ve got lots of other tutorials for Premiere Pro, After Effects, and filmmaking in general! If you have any questions, let us know in the comment section below.  

Thank you so much for watching and we hope to see you in the next video!

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