Invisibility cloak

[Perfo]

Hello all, this is my first post though I have been lurking for a while.
I didn't really have any use for VSDC before I tried it but it has sorta kicked off my interest in video manipulation.

I can do the green screen stuff when you over lay a static green screen on top of background video and make the green bits (or blue) transparent. This works great providing the lighting is uniform enough.
However I'm trying to do an invisibility cloak type effect (as in Harry Potter) so two videos that are identical except the top layer has an extra object in it and this object gets covered by the green cloth and thus disappears (goes transparent and shows the background).
I've been at this for a while and consulted with the normal oracles (google and YouTube) but can't find any pointers on how to do it...
I have another similar project that is also equally above my knowledge but I'll start another thread on that one...

Of course please excuse me if there is already a thread somewhere on this forum discussing the same thing but I couldn't find it if there is...
Thanks

[poisondeathray]

Hello all, this is my first post though I have been lurking for a while.
I didn't really have any use for VSDC before I tried it but it has sorta kicked off my interest in video manipulation.

I can do the green screen stuff when you over lay a static green screen on top of background video and make the green bits (or blue) transparent. This works great providing the lighting is uniform enough.
However I'm trying to do an invisibility cloak type effect (as in Harry Potter) so two videos that are identical except the top layer has an extra object in it and this object gets covered by the green cloth and thus disappears (goes transparent and shows the background).
I've been at this for a while and consulted with the normal oracles (google and YouTube) but can't find any pointers on how to do it...
I have another similar project that is also equally above my knowledge but I'll start another thread on that one...

Of course please excuse me if there is already a thread somewhere on this forum discussing the same thing but I couldn't find it if there is...
Thanks

I'm not quite clear from your description on what you want... what is the background info ?

Typically you'd just mask out the object, if you wanted it to "disappear" - it's much easier

What is the purpose of the green cloth? Were you thinking of "chroma keying" ? or is the cloth part of the presentation ? Like a magic show ?

[jagabo]

Shoot background. From same camera position shoot the person with the invisibility cloak (green cloth). Chromakey on green cloak.

[Perfo]

Ah OK sorry if I didn't explain myself very clearly..
Yes Chromakeying is what I'm trying to do with the cloth. The problem is the mask (green cloth) moves.

So
Shot scene one which is an empty room.
Shoot scene two with all details the same except now a person walks across the room.
Overlay Scene two on top of Scene one.

The person in scene two gets out of their pocket (or wherever) a green bit of cloth. The green cloth is chromakeyed and thus any part of person covered in the cloth will be transparent and show the background video (scene one) and thus appears invisible....

Ah you may have just triggered a thought that may work....

Don't shoot scene two the same as scene one (bar the person) do a full green screen back drop on scene two and have the person walk across it and then chromakey out the green screen.
Now overlaying the videos will look normal with a person walking across scene one but hopefully if a bit of green screen is produced and put in front of the person they will disappear ..

If this works then the answer was a simple as I thought it should be... Of course any other suggestions will be gladly received...

[poisondeathray]

Chromakeying is not very accurate and very finicky. You need perfect lighting for good results, and there are often many issues and complications

If you greenscreen the background completely you will lose realism like reflections of the environment, shadows . It's a lot of work to put those back in . It's a lot of work to realistically composite someone back into an environment .



Masking / rotoscoping will give you perfect results if you have identical locked off shots . One background "clean plate" , One with the foreground actor or object.

Greenscreen is useful if you don't have the environment (e.g. you can't shoot at some expensive location/ environment . Or maybe it's a sci fi , non real background)

[Perfo]

So locked off shots...
does that mean

Set up my tripod and camera and film the room for say 10 seconds (scene one)
now (leaving everything else the same ) film the room again for 10 seconds but this time have the person walk across the room ( scene two )

How would I now do Masking or Rotoscoping on this to produce the person disappearing as they pull a cloak over them ? is this possible with VSCD ?
Thanks for the reply....

[poisondeathray]

So locked off shots...
does that mean

Set up my tripod and camera and film the room for say 10 seconds (scene one)
now (leaving everything else the same ) film the room again for 10 seconds but this time have the person walk across the room ( scene two )

Yes, locked off means tripod, no camera movement

This only works if you plan to use the same room for the background in the final shot. If your location is set on some exotic planet etc.... and your want to replace the room, then go green screen

How would I now do Masking or Rotoscoping on this to produce the person disappearing as they pull a cloak over them ? is this possible with VSCD ?
Thanks for the reply....

masking / rotoscoping is just animated masks . You just use a pen too and draw a shape, move the shape and points over time (keyframes) . I think older VSDC versions had masking , but newer ones only have it with the "pro" version

"disappearing as they pull a cloak over" - Is this where only a head remains , or total person disappears? If parts remain, or you want transition off parts in different timing (not whole person all at once) you'd have to rotoscope that anyways even with a greenscreen

[smrpix]

If your green cloth is bright enough and properly lit you can probably get 90% of the way there with chromakey alone. then you can rotoscope out the remaining flakes and imperfections.

[jagabo]

I don't know about VSCD but there are lots of examples with different programs at Youtube. Search for "invisibility cloak effect". For example:

https://www.youtube.com/watch?v=ctBM4f6kb04
https://www.youtube.com/watch?v=5afbghglEF4
https://www.youtube.com/watch?v=M_XwblQck_c

[poisondeathray]

But another problem with chroma keying approach is the "cloth" will be green . So do you want to "see" this person take a "green" cloth out of the pocket ? How does this play out in your mind ? Can you describe in more detail ? There are ways to change the color of the "green" cloth, but probably easier using masks

If it''s something like harry potter , you definitely want to use masks
https://www.youtube.com/watch?v=KtgdoZFIFZs

[Cornucopia]

Also look up difference matte.

[Perfo]

Wow A lot of good advice here and a lot of learning for me..
It is just like the Harry potter type that I'm trying to recreate. The backgrounds are the same in both videos.. and I wouldn't mind someone seeing the person getting out a green cloth but hoped it would be invisible as it got taken out of the pocket...
I'll go and do some studying... thanks...

I've Had a look at the various links you've posted and yep that's the kind of thing. Some good effect. I wont be buying Adobe Pro anytime soon though so maybe blender is my best best....

[poisondeathray]

Wow A lot of good advice here and a lot of learning for me..
It is just like the Harry potter type that I'm trying to recreate. The backgrounds are the same in both videos.. and I wouldn't mind someone seeing the person getting out a green cloth but hoped it would be invisible as it got taken out of the pocket...

If you key out the cloth/cloak, how do you know what he's taking out of the pocket ? You won't "see" it . So it might be a dog or a cat, or a hat... etc....

If you're ok with that, then all you need to do is in jagabo's 1st link . With a proper key you shouldn't actually "see" the cloth, you see that in the tutorial clips because they are improper keys and remenants of shadows of the cloth . In the Harry Potter clip, you see the cloak (it's not green) before he puts it on. l suppose you can "toggle" on the key when you want it to

[Perfo]

I've seen a cunning idea on one of the videos and that is to have the cloak green on one side and another colour on the other and thus you'll see it until it gets flipped over and covers the person...