Geeky nerd stuff.* I'm picturing a 3D version of this for future
  3D image files that will be voxel based and allow for
  recombining of 3D objects easily. This is the 2D version
  currently in use. The key to making HUGE image files from a
  bunch of smaller ones ("tiles") is knowing WHERE the little
  tiles are supposed to go in the big gigantic final image. To do
  so, you need a coordinate system.* You need a master map with
  coordinates, and then each image needs to have its length and
  width, as well as the location on the map that it's supposed to
  go. A utility called GDAL_MERGE can magically put the puzzle
  back together again. I'm envisioning (if it doesn't already
  exist) 3D voxel based image files, with the ability to have
  their coordinates on a final, larger 3D image so that it can
  "self-assemble". [sort of like artificial intelligence but more
  like the voxel matrixes (something like a chunk in [1]#minecraft
  ) - knows exactly where it needs to go]. So, that's where my
  brain is at.

References

  Visible links
  1. https://plus.google.com/s/%23minecraft