Multi-gigapixel video wall, the low-cost driving of
So given the speculation about having a couple of forty-foot walls in a travel trailer completely covered with what amounts to a high-resolution LCD screen, the problem became how to use that hardware.
Your PC might be able to drive a two-megapixel display at 100 frames per second. But if you try and scale that up to a ten-gigapixel wall, you're looking at nearly a minute per frame. You can get a bunch of PCs, of course, but then there's all kinds of power considerations, not to mention having to synchronise them and then have them sit mostly idle when you're not using the wall for anything more complex than a single 24-inch display.
So I cobbled together a method for getting around all this which doesn't need massively complex electronics built into each of several billion pixels, or a hundred PCs maxed out on video cards, or any one of those sorts of things.
With three bits of memory per pixel (and probably you could do two) and some tiny specialised hardware off to one side, you can tell any section of wall to program itself so that only certain pixels receive 'direct' video feeds from a multiplexer which handles all incoming video streams. In a fraction of a second, all the other pixels in that area are told to take their cue from a particular one of their neighbours. From that point on, each pixel with an external data feed will be rippling its colour information out to its neighbours. At 100 pixels an inch, and a forty-foot wall, one 'master' pixel might be driving anywhere up to a couple of hundred close neighbours. Even at local speeds of a couple dozen kilobits/second, that's sufficient to attain total coverage in under a hundredth of a second - plenty fast for even the twitchiest games.
For an encore, the enclosed area could track where people are located and adjust the number of 'master' pixels actually needed to satisfy human vision. There's no point in having fine control down to a hundredth of an inch if people are sitting thirty feet away watching the movie on the big screen. Likewise, if someone is eyeballing the screen from up close, the feed in that small area could be nearly 1:1 (for simulated environments - there's not much point in interpolating a TV feed any further), but much less at the ends of the screen twenty feet away. In effect, the wall would look nearly pixelless no matter how close you got. It'd be a nice trick for things like fractal wallpaper or virtual spaces with varying texture resolutions.
Of course, it would break down if you had twenty people all scrutinising a full-wall, full-motion-video clip from two feet away along every stretch of the display, but that's unlikely to happen. Using bistable display tech, the amount of power and raw bandwidth needed to drive even a full LAN party of normal-size screens should be able to be kept fairly minimal.
What keeping me thinking now is that on the outside of the split-level trailer, de-opaquing the outer layer would allow the side of the trailer to act as a sixteen-foot-high, forty-foot-long cinema screen - EXCEPT that there would be an unlit stripe between the two levels. I suppose there might be a way to make the upper and lower halves match up externally, although it'd need some clever positioning mechanics.
Heck, you could feed a telecast of the Big Game (translate to local equivalent) onto there, and be the most popular person in the neighbourhood / trailer park for a day :)
A wall-sized screen inside, though, could be much more fun. DDR or Guitar Hero, anyone? Or the Wide, Wide World of Warcraft? Or Second Life at life-size? Or anything with a Wii? Party time much?
Your PC might be able to drive a two-megapixel display at 100 frames per second. But if you try and scale that up to a ten-gigapixel wall, you're looking at nearly a minute per frame. You can get a bunch of PCs, of course, but then there's all kinds of power considerations, not to mention having to synchronise them and then have them sit mostly idle when you're not using the wall for anything more complex than a single 24-inch display.
So I cobbled together a method for getting around all this which doesn't need massively complex electronics built into each of several billion pixels, or a hundred PCs maxed out on video cards, or any one of those sorts of things.
With three bits of memory per pixel (and probably you could do two) and some tiny specialised hardware off to one side, you can tell any section of wall to program itself so that only certain pixels receive 'direct' video feeds from a multiplexer which handles all incoming video streams. In a fraction of a second, all the other pixels in that area are told to take their cue from a particular one of their neighbours. From that point on, each pixel with an external data feed will be rippling its colour information out to its neighbours. At 100 pixels an inch, and a forty-foot wall, one 'master' pixel might be driving anywhere up to a couple of hundred close neighbours. Even at local speeds of a couple dozen kilobits/second, that's sufficient to attain total coverage in under a hundredth of a second - plenty fast for even the twitchiest games.
For an encore, the enclosed area could track where people are located and adjust the number of 'master' pixels actually needed to satisfy human vision. There's no point in having fine control down to a hundredth of an inch if people are sitting thirty feet away watching the movie on the big screen. Likewise, if someone is eyeballing the screen from up close, the feed in that small area could be nearly 1:1 (for simulated environments - there's not much point in interpolating a TV feed any further), but much less at the ends of the screen twenty feet away. In effect, the wall would look nearly pixelless no matter how close you got. It'd be a nice trick for things like fractal wallpaper or virtual spaces with varying texture resolutions.
Of course, it would break down if you had twenty people all scrutinising a full-wall, full-motion-video clip from two feet away along every stretch of the display, but that's unlikely to happen. Using bistable display tech, the amount of power and raw bandwidth needed to drive even a full LAN party of normal-size screens should be able to be kept fairly minimal.
What keeping me thinking now is that on the outside of the split-level trailer, de-opaquing the outer layer would allow the side of the trailer to act as a sixteen-foot-high, forty-foot-long cinema screen - EXCEPT that there would be an unlit stripe between the two levels. I suppose there might be a way to make the upper and lower halves match up externally, although it'd need some clever positioning mechanics.
Heck, you could feed a telecast of the Big Game (translate to local equivalent) onto there, and be the most popular person in the neighbourhood / trailer park for a day :)
A wall-sized screen inside, though, could be much more fun. DDR or Guitar Hero, anyone? Or the Wide, Wide World of Warcraft? Or Second Life at life-size? Or anything with a Wii? Party time much?