# Thread: Symmetrical mirror

1. ## Symmetrical mirror

Do mirrors that show half your face put on the other half like this:
http://www.gocomics.com/phoebe-and-h...orn/2018/02/01
actually exist?
If so, how do they work? And how can I get one?
When I try googling, all I get are these four things:
https://en.wikipedia.org/wiki/Mirror_symmetry

2. I think the giveaway is that the story also involves a unicorn.
I doubt if anyone makes them, since they'd be deeply unsatisfactory. But you could make one out of a conventional flat mirror (for the mirrored half) and a corner reflector (for the "unmirrored" half). Then all it would require would be careful relative positioning of head and mirror halves.

Grant Hutchison

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you could photoshop your face to reflect one side or the other.

4. Actually, years ago someone told me about these, so I know they are at least an Urban Legend and not something Simpson just dreamed up.

5. Video displays show how you're seen by others instead of showing the mirror image that we're used to seeing. While finding the center of a face and generating a symmetrical image is rather complex, I'd expect one could be designed to show you something appropriate, including alternating which half is mirrored.

6. There are any number of mobile phone apps that do this for you, but I think with still photos rather than realtime video.

Grant Hutchison

7. You young whippersnappers and your phone apps. If you want to see yourself as others do, you don't need a video display or a phone - just look at yourself in an elevator that has mirrors for walls.

When you look into the corner of two mirrors perpendicular to each other, you see yourself as others see you.

Lettering is correct:

The part in her hair is correct:
Last edited by DaveC426913; 2018-Feb-01 at 08:10 PM.

8. Yeah. That's the "corner reflector" bit of my post. But you need to apply that effect to the same half of the face as is being directly reflected in a flat mirror, and combine the two reflections along the midline of the reflected face, in order to produce the effect Tom wants. It's possible, but it would be a real faff, since all three components (flat mirror, corner reflector, face) need to be in a unique set of positions relative to each other, or the effect won't work. I can't see why anyone would want to do that.

Grant Hutchison

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I still don't see how to do it. And I don't see how to get the light
paths the same length so the two halves will be the same size.
And will it work for both eyes simultaneously?

-- Jeff, in Minneapolis

10. Originally Posted by Jeff Root
I still don't see how to do it. And I don't see how to get the light
paths the same length so the two halves will be the same size.
And will it work for both eyes simultaneously?
No, it won't work for both eyes simultaneously. One of the reasons I described it as "deeply unsatisfactory".

Grant Hutchison

11. Originally Posted by grant hutchison
No, it won't work for both eyes simultaneously. One of the reasons I described it as "deeply unsatisfactory".
Are we talking about simply reflecting your whole face?
Or are we still talking about reflecting half the face onto the other side?

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We are talking about reflecting one half of the face in two images
that are mirror images of each other. One has to be reflected an
even number of times and the other has to be reflected an odd
number of times. I don't see how to do that without the images
ending up different sizes.

-- Jeff, in Minneapolis

13. Originally Posted by Jeff Root
We are talking about reflecting one half of the face in two images
that are mirror images of each other. One has to be reflected an
even number of times and the other has to be reflected an odd
number of times. I don't see how to do that without the images
ending up different sizes.
Hint: the mirrors can be different distances from the viewer.

Grant Hutchison

14. Come to think of it, the person may have meant this:
https://en.wikipedia.org/wiki/Non-reversing_mirror
so perhaps Simpson did make it up.

15. If you put a mirror vertically against your nose, a distant viewer will see your half face plus its reflection, making a symmetrical face. So if you now place a distant mirror where the viewer was, you will see yourself that way. Harry Worth used to stand by a shop window to look like that and raise his leg creating an amusing star jump effect. So a right angle corner mirror will do the trick , but you place one mirror to your mid line so you are now using just one eye. If you double up in a tee square arrangement you get two different symmetrical views and your brain will average them out, maybe.

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I get a half-silvered mirror and four regular mirrors. The half-silvered
mirror and three of the regular mirrors are at 45-degree angles. The
remaining mirror is straight-on and farthest away. A single reflection
in the straight-on mirror for half the face, four reflections in the four
angled mirrors for the other half.

-- Jeff, in Minneapolis
Last edited by Jeff Root; 2018-Feb-02 at 04:30 PM.

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