- were translucent, and
- had a screen behind it
The light arrives at your eye containing both an image of a wall when focusing at 3m and an image of a TV show when focusing at 20m.
Such a light field is not distinguishable from the light field that would occur if the wall actually were translucent and actually did have a TV show playing on a screen behind it
- high-res satellite and airplane imaging of the globe
- public geotagged photos, including compass bearing
- Google Street View road images
- public security cameras on public streets
All of this data can be integrated using software like Microsoft's PhotoSynth, to stitch together a gigantic 3D model of the real globe.
Then, people with Voxel Vision will be able to look around at streets and landmarks that are interesting but physically occluded.
I think he must not have gotten the sonar parts in his half bat bits.