Interesting thing about projected AR, under some odd circumstances (either true pitch darkness or peeking past their ear) you can actually see someone else’s image and therefore visualize the FOV.
It’s been a looong time since I had all these specs in my head, but this ancient, ancient 480p per eye prototype I believe had 70 degrees FOV. https://www.youtube.com/watch?v=M4ll6RqZwUM&t=4m57s
These glasses are the early developer tier of CastAR, which I believe had 90 degrees advertised FOV, roughly comparable to Tilt Five. With a ten-foot diameter sphere and a five-foot-something guy, his head should be in the center and the surface should be 4-5 feet out. https://www.youtube.com/watch?v=TSWNpH2WdFY&t=45s
This rundown of one of the last CastAR generations shown before they ran out of money has several shoulder-surfing shots. You can see the top edge of the FOV a lot, but I don’t think you ever see him run out of horizontal FOV - which in itself is informative. There are also clear shots on the monitor of what the projectors are showing. (I’m too new to be allowed to link three things) v=A4TAppwUMWU&t=45s
Editing because BoingBoing limits new users’ number of replies, we’ll see if @hngr gets notified by mentions in edits. I don’t think Ellsworth’s reply addresses his accusation directly enough. The May Tilt Five video’s legit. You can’t see projected AR either off the retro material, or off-axis; you can see it outside the glasses. Two of the three videos here are examples of seeing (a faint ghost of) the projection outside the glasses by being near enough the axis.
So what are the big surfaces for, if they’re not needed to see the image? They use polarization to stop you from seeing the wrong image; crosstalk. There’s a bell-curve of brightness projected on your face around the axis from the projector to each pixel. Just like some light spills out to the side of a user’s head, some goes in the other direction to the wrong eye. I still can’t post more videos, but check out Youtube video nQRl-Wq1yR8 from 35 seconds and watch the balloon outside the glasses to see the ghosting. If you were looking at it with two eyes instead of one video camera, there would be a ghost on both sides of everything. Usable, but sorta crappy. Nobody’d buy it. Thus, the glasses.
