In the early 1960s I was on holiday in Ibiza; at that time totally off the tourist track and having lots of artists doing their thing. One of them - who was not in the film world - said to me that he had a brilliant idea. As underground trains had a series of windows that were like film frames, you might be able to have pictures along the tunnel so that they appeared to be moving as you passed them.
I explained that you needed a 'gate ' so you only saw the image for a fraction of a second, and that the train would need to have a steady speed from start to finish, apart from the fact that lighting varied along the track, etc. But the idea was not lost on the Advertising people who saw the unused walls of the underground as potential space.
A few years later I noted that Sony had come up with a system showing moving pictures in the tunnel, but I never saw anything indicating it had been used or how it was done, so last night when by chance I switched on 'The Gadget Show' and saw that such a system was now working in the USA I was particularly interested.
Apparently it requires images to be flashed on the walls rather than fixed on the walls, and the flashes synchronised with the train speed. In effect, the train was acting as some form of projector.
The idea of projecting onto unusual screens is common enough; the same Gadget show had ladies parading around with screens built into their clothes. I have seen films projected onto waterfalls, blocks of ice, through mist, onto people, and two movies projected onto a single screen; and I seem to remember that someone tried projecting onto clouds, and the idea of using all your walls and ceilings as screens is just around the corner. One day you will wake up to the sounds of the dawn chorus, and see the sky above and the forest around you, while laying in the comfort of your bed.
The screen I'm waiting for does exist, but is not cheap; It's the 'Head-up-display' used by pilots, where the screen is their visor which is rather like Virtual reality helmets . I would like to be able to put on a pair of glasses and see movies in a way comparable to using an Ipod. I'm prepared to bet that something like that will be around in a year or two.