Warping in Stereo

With this recent batch of vision symptoms comes something ... odd: People look... different.

I notice it first with Deb. After forty-plus years, I recognise Deb. Deb is very very familiar. And yet -- now she looks... different. Her face looks different.

Deb's face is, I'm sure, unchanged. I *see* it as being different. Nose is a different shape. The planes of the face are more rounded. Not overall, rounded in small areas. Cheeks, chin, nose, each are just a little unfamiliar. Differently shaped. Adding up to a face which looks -- less familiar.

I have a quick grope. Yes, definitely Deb. Why does she look different?

Other -- familiar -- family members look different. Today at orienteering old familiar orienteers look... different. (Yes, our orienteering friends are often old :-)

I see a familiar person... the face is not so familiar... when I talk to them they are the person that they... resemble.

Very odd!

I have a vague worry. Is there some brain damage that is not obvious? Is my brain going completely to pot?

And then... I have it!

We see in stereo. Two images, one from each eye. Superimposed, slightly offset. The brain compares the two images and converts it to a three dimensional image, a familiar face.

Now I have lost vision to my left. Both eyes are failing to see what is to the left. A "different" pair of images reaches the brain -- with something missing to the left.

The brain gets a familiar image of the right of Deb's face. The image is missing a part of the left of the face. Superimpose the two images -- and the 3D image will be different.

The brain gets different images, missing stuff at the left. It builds a 3D image -- which is different to an image based on two full images of the same face.

All the 3D parts of a face -- lips, cheeks, nose... are warped -- because a part of the original images (the left part) is missing. The resulting 3D image... is different.

Phew! not a new problem! Just an interesting side-effect of loss of left image.

Perhaps my brain will learn to identify people from the new, lost-left images. Faces will become familiar again... though different.

Meanwhile: don't be surprised if I don't recognise you. I may know who you are but... you just look a little... UN familiar.

Dr Nick Lethbridge / Consulting Dexitroboper

...        Agamedes Consulting / Problems ? Solved

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"No matter how much you push the envelope, it will still be stationery"

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