Originally posted by Andrew Hamilton
I am not sure but I think actually my reasoning here may be subtly flawed :
I have failed to take into account the fact that mirrors are normally orientated vertically and the surfaces we tend to notice when seeing their reflection in the mirrors tend to also be vertical.
If you hold a book in front of you so the pages are horizontal and orie ...[text shortened]... the book is vertical.
Thus this doesn’t quite depend entirely on our perception as I suggested?
If you put two mirrors at right angles to each other, like in the corner of a room, meeting with a very accurate line, no gaps, and you look at that one, the perspective is exactly the same as if you were in that spot, that is to say, you move your right hand and the opposite hand moves, showing the perspective is exactly the same as your own, the opposite of a regular mirror, which, when you look at the image, you move your left arm and the image looks like it's moving it's left arm. It is not a matter of inner perspective, if you have both mirrors side by side, you can see the difference. Like if a wall has mirrors in it and they meet at the corner like I said, just moving over to the middle of the wall gives you the view of a normal mirror but when you look at the corner reflector, the opposite perspective shows. Try it if you don't believe me. Do the experiment, mirrors are cheap.
For it to work, however, the corner mirrors must be exactly at 90 degrees apart, otherwise overlapping images ruin the effect.