Examples of illusory rigid planar patches arise directly from projective coordinate transformations applied to individual images, allowing messages to be left on everyday planar textures in the real world, visible to those wearing the eyeglasses, and on the list of recipients for a particular message (Fig 3).
Figure 3: Message left on the flat wall of department store entrance
remains dormant until recipient of message happens to look
at wall. The act of looking, being mediated by the
apparatus, enables the message to appear as an illusory
planar patch. (Thanks to Jeffrey Levine for help with
work in this figure.)
Face recognition has been used together with `video orbits' to create existential name tags[12] (e.g. don't exist in reality but can be seen by wearer of apparatus) where the name had been entered at a previous encounter or drawn from a database.