When keying the footage, the first method that was attempted was through After Effects which was an easy, simple method especially when compared to how it was done in UE4.
To start off with, import the footage into After Effects and scrub the timeline to a frame where all of the actor is in frame and use the Rotobrush tool to paint out the actor and then hit the freeze frame button to track the actor with the mask. What the Rotobrush tool will do, it will cut the background out only keeping the actor left. Then to get rid of the rest of the green around the actor, use the keylight 1.2 and adjust those parameters until the green around the actor is completely gone without making the actor see though.
The method to keying in Unreal Engine was a much longer and difficult process. To get started, open a composition tab and dock it on the right as seen below and right click and create a media plate. Go to the content browser, right click and go to media and import a media player and a media texture then import the footage and apply it to the media texture.
Once the footage has been added to the media player, select the imported camera and add a CG element. Then create a new texture and change the material domain to "post process" and scroll down and tick the "output alpha box" under the "post process material" drop down menu. Create two parameter 2D nodes and name them the same as the media plate and CG element respectively and plug the RGBA nodes into the A and B on an over node which goes to the emissive colour. This will add the imported camera so that when the composition is selected the footage will be seen playing in the camera view port
To then key out the greenscreen, select the media plate and go down to the "transform/compositing passes" click on the plus next to array elements then the cross under key colours and then select the green and use the below parameters to edit they key.
The keying in Unreal is quite difficult to get right at least with the footage being used as the keying kept on making the actor transparent. As well as the the part of the wall which was in shot wouldn't key out as it was part of the greenscreen.
The way to get around this was to line the footage up with the scene in Unreal and the just render out the camera without the footage in the way then and key the footage out in After Effects and place it over the Unreal render. Doing it this way also meant that that the colour correction on the recorded footage was much easier and flexible than it would have been in Unreal
