How to replace sky in video footage.

Sat Aug 24, 2019 2:23 pm

Hello,

Firstly, I'm really enjoying the product. I'm an audio guy, but I'm quickly getting to grips with it and the documentation is very well put together and helpful. However, I was wondering if you could point me in the right direction to some guidance, or a tutorial for the following:

I want to be able to replace the sky in some video footage with another piece of video.

Is this possible? I've looked for tutorials on this but I can' find any. I've also tried playing around with a few modules but can't seem to get it. Any help would be much appreciated.

Thanks.
Sonics60
 
Posts: 4
Joined: Sat Aug 24, 2019 2:21 pm

Re: How to replace sky in video footage.

Sat Aug 24, 2019 7:24 pm

It is possible but will depend on a few things.

1. How much movement there is in the scene.
2. How much variation there is in the sky
3. What you intend to replace the sky with.

If there is little movement you could use a mask module to mask out the sky.
If the sky is pure blue you could use a chroma key.
If you're replacing a blue sky with a sunset that shouldn't be too tricky but if you're replacing a cloudy sky with anything unsimilar then it is likely you'll see the clouds or inadvertently remove other parts of your image before the clouds.

This is all within Magic. But you could remove the sky in another video editor more suited to this task and generate footage with an alpha channel.

In either case, you could use a combination of multiple masks and several keys to remove much of the sky. It would be a challenge though, until there's a neural net for that.
Sadler
 
Posts: 619
Joined: Sat Aug 02, 2014 7:10 pm
Location: London, UK

Re: How to replace sky in video footage.

Sun Aug 25, 2019 11:45 am

Further to Sadler's comments, if all of the sky is much lighter than any of the rest of the scene you could try the LumaKey module.

Set Falloff to 1.0, check Invert, then adjust Strength to see if this works well enough to be useful. Reduce Falloff for a more gradual transition, further adjusting Strength for optimum results.

If all the above still leaves you with questions, it could be helpful if you post a link to the sky video.
Terry Payman
 
Posts: 542
Joined: Sun Sep 14, 2014 8:15 am
Location: UK

Re: How to replace sky in video footage.

Sun Aug 25, 2019 7:49 pm

Thanks both - this is very helpful and I'll have play with your suggestions.

The footage is a shot of a girl walking across a field. It's a dull day but there's a consistent cloud colour in the sky. Typical Wales! :)

It's a fixed shot with no camera movement. I'm hoping to get the sky to react in an 'other worldly' way to piece of music.
Sonics60
 
Posts: 4
Joined: Sat Aug 24, 2019 2:21 pm

Re: How to replace sky in video footage.

Sun Aug 25, 2019 7:56 pm

Sonics60
 
Posts: 4
Joined: Sat Aug 24, 2019 2:21 pm

Re: How to replace sky in video footage.

Mon Aug 26, 2019 2:36 pm

I went with the LumaKey method in the end. It's not perfect but it give's a nice vintage feel to it which will suit the rest of the video and song.

Thanks again for your help. :)

Adam.
Sonics60
 
Posts: 4
Joined: Sat Aug 24, 2019 2:21 pm

Re: How to replace sky in video footage.

Tue Aug 27, 2019 12:37 am

Glad that worked for you Adam! :)
Terry Payman
 
Posts: 542
Joined: Sun Sep 14, 2014 8:15 am
Location: UK

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