Trying to make "GHOSTS"

killian_mcgregor wrote on 8/3/2003, 5:13 AM
Here's what I have...I have one video track of the living - that MUST remain solid. I have another video track of a ghost - that needs to be transparent. Without cropping or using a cookie cutter, how can I make the two tracks appear as one? With one person solid and the other transparent? I have not started shooting the project, but I do have a screen test. I want to know for certain that I can have the two images interact before I start shooting. If it absolutely CANNOT be done, then I will shoot it where I will be forced to use the cropping or cookie cutter.

I want to be able to have, for example, the ghost to pass in front of the living. I've tried everything, but always the two images end up transparent and I need one of each.

Comments

TorS wrote on 8/3/2003, 5:43 AM
What you're trying to do will make the natural person less than 100% solid. But maybe you can try different things to camouflage that fact?
Shoot the ghost's background alone once and then with ghost. Combining those two shots should give you a transparent ghost to begin with. On top of that you could experiment with light rays and other FXs (keyframeable, to move with the ghost) and then combine the result with the shot of your natural person. The lighter areas on that person will be most likely to let the ghost tracks through, so you will plan make-up, lighting and costume clours carefully. Try to not let your ghost pass in front of the natural person's face (at least if it's a pale face). Let us know how you're getting on.
Tor
Second thought: It's probably when the ghost passes BEHIND your natural person the problems begin, because some of it may show though where it should not. My advise is the same, though.
farss wrote on 8/3/2003, 6:26 AM
Do do it right is a bit more complex than it might seem, I guess it depends as Tors said if the 'ghost' is going to pass behind the real person.

I think you need to green screen both of them seperately. That way you can have one track as the backgound, next one the 'ghost' at say 50% transparency and chroma keyed and then on the top track the real actor(s) at 100% again chroma keyed.

The staging is going to be critical. You might need to contruct a dummy set if there's objects that the actors and ghost have to move around. Make the props for the green screen shoot green as well and pay great attention to lighting.

Which reminds me I've seen an analogue chroma keyer that can add shadows and reflections from the object being keyed onto the background. Anyone done that in VV yet?

Sure like to know how it works out, oftenly the simplest illusions are the hardest.
Former user wrote on 8/3/2003, 8:29 AM
If your camera shot is locked down, you can shoot the scene with the living person. Then shoot with the dead person.

On Video, use the living as your bottom track. Lay the dead on the second track, and use the TRACK level adjustment to make it transparent. If your camera did not move AT ALL, then the set will appear the same but the top track will show the differences (ala your actor) as transparent.

Dave T2
roberths wrote on 8/3/2003, 11:51 AM
I am a newbie to Vegas and digital video and I'm just brainstorming. If I remember correctly there is a function in Vegas to export video frames as images. You could then set up an action in PhotoShop that would mask around the ghost and maintain transparency. That action could be used in a batch clean up of all the ghost frames that were exported out.

If you can find some software to render the frames back together as avi and provided the transparency is maintained (like I said I am not that familiar with DV just yet) you could take that video and overlay it on the footage of the live person.

This is a very good question and Killian's and TorS approach seem interesting.
Rob
Spot|DSE wrote on 8/5/2003, 11:07 PM
you could export the frames as PNG files via Quicktime, but shooting on a green set is an easier way of accomplishing this. the keyed footage can have shadows, etc all added to it.