Hovering Cup

S

Sofie

New member
Hey guys,

I'm making a movie about coffee, in which a cup of coffee suddenly begins to soar into the air in flashes of strobe light.

I'm just running out of ideas on how to make that cup hover. I have been thinking about painting a stick green (green-screen colouring), sticking it to the cup, filming the whole hovering thing using the stick, then removing the stick in post.

I think it could be done, but is there an easier way?

Also, I don't know quite, which colour to use to paint the stick, and how easy it will be to remove in post, do you have a glue?

Hope you can help (I could use some...) :)
 
The color you need for Chroma Green can be found by googling: chroma green paint

Which one you buy just depends on your budget.

Make sure you get a decent plate shot without the stick/cup to fill in.
 
Talk to whoever's doing your editing and post-production, to find out whether they have the chromakey tools for this sort of thing. You all need to plan fx like this together before shooting, including doing a few test shots.

The good news is this shot shouldn't be too hard, with planning and testing.
 
If you're sensible about your camera move and the length of your shot, you likely don't even need to chromakey anything and can remove the stick with roto and a cleanplate background. Unless the stick is very evenly lit it will likely be just as much trouble to key as to roto and you save yourself getting green reflections in anything else in the shot. I can't speak for your fx people, but if I was doing it, I'd just have a dark stick that blends in rather than a bright green stick that will really pop out if its not properly removed.
 
Sorry if this is too obvious and you've already thought of it and rejected it, but just in case, could you just composite the cup?
 
Rainer, maybe explain "compositing" to help out. Talk to us about your procedures, if you are comfortable with it.
 
Could it be done with camera angles?
Low tech, attach your "stick" on the far side of the cup, using the cup to block it from view. Support the whole subject with a stand or such and have a solid color curtain between stand and cup to hide the stand. Light to hide shadows. Then just lower the camera during the take to simulate the cup floating up.
 
I did this effect for a personal project years ago. I attached a wire hanger to a can of beer, painted the wire chroma green and shot it over green screen. The downside to doing it this way is that the cup picks up all of the micro movements of your hand. It's almost impossible to make it move smoothly. Fortunately for me in this case it was all right because the piece I was putting together was supposed to be campy so the wiggly cup worked.
 
To get smooth movement of the cup you could attach it to your stick, attach the stick to a solid surface like a table, paint the stick chroma green and set the whole thing in front of a greensceen. Then put your camera on a jib or a slider that has vertical mobility and film a nice smooth pedestal move from high to low with the cup as the focal point. Then in post, key out the cup and move it from the lower portion of the frame to the upper portion matching the speed of your green screen pedestal move. If you don't have a jib or a slider with vertical capability, you can mount the cup horizontally and use a standard slider to track the move. Then in post, rotate the cup 90 degrees, key out and you're good to go. All of this, however, assumes you're shooting with enough color information to pull a good key.
 
Doc Bernard said:
Rainer, maybe explain "compositing" to help out. Talk to us about your procedures, if you are comfortable with it.
Click to expand...
Sorry, just noticed this request for more info. Green screen is an example of compositing, and usually the green screen image is static, but it doesn't have to be. Can you recall the opening in Forest Gump? A leaf drifting through the scenes? The leaf wasn't shot as part of the scene - there's no strings. The leaf is just shot separately, then the background is masked or keyed out (e.g by first shooting it on a green screen) , and then the leaf footage is resized, rotated, blurred, keyframed and shown over the footage. Vegas, After Effects, for example, and I guess most higher level NLE's, handle this effortlessly.
 
Depending on how near you are to the cup when it rises and how decorative the cup is then have you thought about CG. If it's a simple white coffee mug that would be really easy to do in CG. I'd even do it for you if you don't have CG experience :)

Pete B
 
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