[helene_t]

The bus station in Lancaster is build of glass so you can see the buses on the other side. Usually you see them through two glass layers. Then they look like mirror images (except that they are not mirrored but as long as I don't pay attention to the text on the front and the seat of the driver, I perceive them as mirrors of buses at my own side).

OTOH buses that I see through only one glass layer (say, I see it through an open door) don't look mirror-like.

Why is this? Do the images get blurred in a different way in a mirror than through one layer of glass?

[hotShot]

The reflection happens at the glass surfaces and depending on the angle the light hits this surface the reflection is incomplete. (I bet the "glass" from the bus stop is not simple glass, more of a multi layer material.)
Since glass has 2 surfaces, you will get 2 reflections displaced by the thickness of the glass. Both images together appear sort of dizzy.

If you make a silver coating on one surface (a mirror) the reflection at this surface is complete and therefor more intense so it dominates the front surface reflection.

See http://en.wikipedia....iki/Reflectance for more details.

[helene_t]

hotShot, on Jun 3 2008, 12:21 PM, said:

Since glass has 2 surfaces, you will get 2 reflections displaced by the thickness of the glass. Both images together appear sort of dizzy.

Yes, I would think that this is what accounts for my perception of an image being a mirror image rather than a real image. As you said a high quality mirror (like a silver plate) does not have the same effect.

It seems that the image of the bus that is behind two parallel glass walls (the distance between them being some 7 meter I think) gets "dizzy" in a similar way. Maybe if they are slightly out of parallel (diverting by a fraction of a degree), light beams from a particular point at the distant bus can reach my eyes via two paths?

[hotShot]

Looking through 2 planes of glass you have 4 surfaces.
You will see the re-reflection of the mirrored image at surface 3 mirrored again from surface 2.
I hope that is somehow clear. (Similar to a kaleidoscope.)
This might cause a sort of dizziness similar to that of the mirror image.