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A Roman “hologram” effect ring found in the grave of 1st century AD noblewoman, Aebutia Quarta.
(lemmy.world)
The ring is thought to depict her son, Titus Carvilius Gemello, who passed away at age of 18. Found at the Grottaferrata necropolis close to Rome.
is it really hologram or simply a miniature covered in glass?
A miniature, but the relief would be exaggerated by the curvature of the glass, so the image looks deeper than it actually is.
Holograms require lasers, don't they? So I would say the latter.
I can't be sure, but this appears to be the Hollow-Face optical illusion. It would be achievable with this technology as well
Hollow face illusion produces a face that appears to follow the observer. This just looks like a sculpt under glass.
My guess would be a painting under the rounded glass piece to make the painting move slightly through the curvature of the glass. But I’m just some guy.