The magic behind the curtain for the Future Technology Pavilion's big rear projection screen (above) consisted of six Digital Projection D-Vision 30-1080 DLP projectors, each responsible for filling one sixth of the image, combined with edge blending to hide the transitions from one projector to the other. These projectors offer a short throw, permitting a short, 9-foot distance from projector to screen.
Once you divide the high definition source image into six segments, each of those segments will be far smaller in pixel count. Each of these segments must therefore be upconverted to match the projector's native resolution. The processing is further complicated by the fact that the screen used here is 2.35:1, not the 16:9 that would be a direct multiple of the six projectors' native resolutions. In addition, allowance must be made for overlap where the images meet. An overlap of about 13% is needed to provide for the edge blending. And the edge blending itself requires major processing power.