Optical illusion: transparent metal bars
I noticed this optical illusion when I was siting in Druckers in Birmingham’s Bullring. I was looking at it absent-mindedly for a while before I spotted it.
Directly outside the window, which looks out over the pedestrian area and down towards St Martin’s Church, are wrought metal railings. Their bars are squared rather than rounded, giving them a flat edge.
Gradually, as I gazed out of the window, I became aware that I was apparently looking straight through these solid metal bars: through them, not between them. As people walked by outside, it seemed I could see them walking behind the flat, rigid metal.
My guess is that the glass of the window reflected the scene outside onto the metal.
I assume that as the proximity of the two was so close, and given the angle of my gaze, the reflection was such that the resulting image was seamless.
The illusion vanished if I moved my head, and could only be seen through those bars in the photograph (ie those directly in my line of vision).
Which means, presumably, that I would not have seen it had I not sat in that exact location and in that exact position.


