A very large display

This idea was inspired by an art project: printing out (in lots of little sections to be pasted together) a satellite or aerial photograph image of an entire city and laying it out on a large flat surface like an aircraft hangar or (indoor) football field. Cover it with lamination or plexiglass. Walking over it makes people feel like a bird. Paper is still the most practical implementation of the idea.

On the other extreme in terms of price and practicality is a huge floor-sized display. Scaling 100 dpi to a 100 m by 100 m area is a 155 gigapixel display. A somewhat crude implementation could place lots of small displays next to each other, with ugly gaps between the displays, so not a continuous image.

Another implementation uses a few moveable or steerable projectors mounted above or below (better below to avoid shadows). The projectors track the person as they walk around the field and project the image just in the neighborhood where the person is.

With multiple people walking around, more projectors are needed.

Continuing the theme of locality, we can have a featureless arena and give each person a high resolution heads up display with head tracking. We want a heads up display that you can simultaneously see real reality and the projected virtual reality, rather than a completely immersive virtual reality. We want two people to be able to converge around the same spot, see each other, and be able to point and discuss a feature of the image.

The heads up display offers several advantages over previous ideas. The image may be projected to appear at waist or chest level rather than floor level. With sufficient resolution, we can maintain the illusion that the image continues far off rather than is just locally projected. The part of the image at a distance must be rendered to match the eye's focal distance, because you can see through the display to real people and objects in the "featureless" room.

The virtual environment has the additional feature that the image may be 3D, displaying building heights and topographical elevation. The initial physical (paper) model above can also do 3D with 3D printing, but it takes additional measures so that viewers will not crush the model or twist their ankles: load-bearing plexiglass, for example.