Projecting onto Fog

[bobgaggle]

I'm just throwing a question out there that's been bugging me since i did a production of The Wizard of Oz. We scrapped this idea before trying it, but I've been wondering if anybody's had luck with it.

During the tornado scene, dorothy sees the images of people and objects through her window in the swirling clouds. If you filmed an actor flying on a broom in front of a green screen, then edited everything but the actor out, could you project the image onto fog through the window? Assuming the window is covered in glass/plastic, and the fog contained to ensure high density, would you be able to see the image in the fog?

[len]

There is a fog screen, but it's waaaay expensive. http://www.fogscreen.fi/en/index.html They offer rentals in the U.S., but when I first inquired about a dealership 2 years ago, it was about $102,000 to purchase, and that was with a stronger dollar.

If you're going to green screen, why not just find/film an image of clouds or haze, and mix the two? Pull the focus out a little and it should work fairly well, at far less expense.

[wolf825]

The problem with this trick is to get the fog to maintain a even flow density and thickness in a flat "wall" or "screen" formation....it can't "cloud" or get uneven in thicknesses and density for a projection to stay fairly uniform. If you contained the fog somehow--possible...but it would probably also just reflect off the glass or plexi and you may get a double image or distortion--and at that point you may as well not bother with the fog. Fog from a fog machine is temperature sensitive for dispersal and if you move it it cools and dissipates and it can get dispersed everywhere from any air movement--so it is especially more difficult to wrangle than a wet or mist screen which Len posted about, which works with gravity and small fans. I've seen this mist curtain effect in person at LDI and I thought it was a great effect I was very interested in...until I also found out the price... :D

-w

[bobgaggle]

Thanks for the thoughts...I checked out the fog screen...WHERE DO THEY GET OFF CHARGING THAT MUCH FREAKIN; MONEY?!?!?!?!

[What Rigger?]

Try Pirates of the Caribbean and Indiana Jones at Disneyland.

Pirates projects Davey Jones onto a fog screen that you actually pass through the bottom edge of (humidity depending) and Indy does it with a clip of large rats crawling down a "tree branch" or something in your path.

[kwotipka]

Alright, just spitballing here. If you are just looking for some sort of translucent effect and don't have to walk through the effect:

Make a wire frame as wide as a roll of something like light opal diffusion. Drop it into a smoke effect with a custom nozzle to "help" control the flow. Depending on lighting effect, may or may not work. Or, bury the screen into the set by making it a window.

One problem with smoke I see is that anyone off axis of the screen would see the projector beam in the smoke.

I have seen the semi translucent screen effect in product displays at local malls. Maybe it's time for a road trip to steal some ideas...

kw

[Hughesie]

u2 did it in stadum shows i dunno what projected the fog but the projection was a high end dl2


edit during the vertigo tour

[gafftaper]

I did this about 5 years ago for a production of Oz for the Wizard. I had a platform with a trap door in it for the witch melting scene. When it came time for the wizard, we dropped the trap door open and cranked the F100 to full just shot it straight up out of the platform. No fancy expensive rig. Had a video camera on stage for the wizard to speak into from "behind the curtain". Shined a green like on his face. It worked surprisingly well. No it won't be HD quality like the expensive rigs, but it worked just fine for what I wanted.

[ruinexplorer]

I helped install a fogscreen at the Penthouse club in Vegas. It's really cool, but you have to REALLY control air movement. The wet mist works better as long as you can control the water on the floor. However, neither of them would work for your application. I would recommend layered projection on scrim. The scrim would take out some of the definition of the video, but that's fine since it's all blurred in the tornado anyway. If you were able to use a media server so that you could have your base layer as the tornado with the rest of your images floating across that, you would probably get the feel of the movie.

[wadeace]

Originally Posted by What Rigger?

Try Pirates of the Caribbean and Indiana Jones at Disneyland.

Pirates projects Davey Jones onto a fog screen that you actually pass through the bottom edge of (humidity depending) and Indy does it with a clip of large rats crawling down a "tree branch" or something in your path.

If I remember correctly they were using a co2 base system for that not a fog machine with the fluid.

If I wanted to achieve the fog screen effect, I would take a tube or pipe of drill evenly spaced small holes in said pipe and suspend said pipe from a baton, connect the pipe to a fog machine on either side.

The thing you would need to keep in mind is the foggers would need to be low laying foggers, there is the cost. With low laying fog it will cascade down creating a screen.

Also you can’t just lay the pipe on the floor and hope regular fog will act the same just reversed. You would actually need to line up foggers and angle the jets up to achieve this effect.

You could use co2 and vary the pressure for both effects.

For the wizard of oz show, I feel it would have worked. The problem is that you are going through many different mediums. your going through normal air through glass through air through more glass on to fog so you’re not going to be able to achieve a very sharp and precise image, but I suspect that you that would be ok because its a tornado scene. Also might have had glare and flash issues because of the glass.