Walking through door/wall effect

I’m working on a show that has quite a few shots where a ghost will walk through doors/walls. The initial brief is that there won’t be any real effect on either the ghost or the solid objects they pass through (so no transparency or ghostly look dev as it stands). I’m going along the route of matting out the actor and just trying to do something “realistic” with the edges as they pass through. But as there are so many it would be good to get a technique that isn’t too time consuming if possible. I just wondered if anyone here had worked on anything similar or knew a couple of tricks that would help? Thanks

It all depends on what they’ve shot, is the person in the scene or a separate scan, either in the scene or on greenscreen.

I would approach it as first getting a matte of your subject who will pass through the wall. Then displace to create some depth (generate normals, paint/track shapes in, light, etc.). Probably several ways to go about that step, each with its own trade-offs. Then use the displacement to animate the subject going through a plane/wall. You should be able to get the nose and face to emerge first, then chest, etc. if I’m thinking about this correctly. The duration of the effect will determine how much effort you have to put in to make it passable.

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Separate pass walking through with the door open no green screen. Then a clean pass of the door closed.


If it’s the show I’m thinking of then look at the previous series to see what was done and client expectations

And if by chance you’re not working on the show I think. Then here’s three examples of varying levels.
Ghosts (uk comedy on iplayer)
Ghosts (us adaptation also on iplayer)
Lockwood & Co (Netflix)
From the sound of what you originally said then I’d say the uk version of Ghosts is a good example of what you’re after.

This is funny to me, because when we were all back on facebook, there was a person that for months and months was asking questions about ghosts walking through stuff and smoke effects and mattes and interaction with walls. Then they asked about a shot where people were playing volleyball with a severed head. Season 1 of ghosts comes out a few months later-- lots of ghosts walking through walls, ok… but not definitive proof. Then bam, playing volleyball with a severed head and it was like, yep, there it is…


Hi Rob. It’s a new show, so no previous reference to follow. Ghosts was actually one of the initial references that came to mind when we started testing for the show. One of my main considerations is that the pass through only happens a handful of times and it’s in an otherwise pretty “realistic” drama. So it would be easy for the ghost effect to suddenly feel jarring. Also the actor is often walking quite slowly up to and through the objects. If it’s quicker it would definitely help. I think it’s going to have to be the matting displacement route I’m already on. Thanks for all the responses.

if the actor is shot on chroma bg behind the door you could key it and keyframe a matteedge erode to get that walk through effect pretty easy maybe? this or ml depth matte with some noise/blur on it. (maybe a better one than the flame ml)

if you can find something automatic to create the pass-through matte i think that would make it a lot faster

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