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They're technically not holograms but Pepper's ghost. https://en.wikipedia.org/wiki/Pepper%27s_ghost https://en.wikipedia.org/wiki/Pepper%27s_ghost Calling th

• unicornfinder 7y ago
  I mean, it depends. They're not always peppers ghost. It's quite common to just use transparent projector screens, as peppers ghost doesn't handle viewing angles all that well.
  • debt 7y ago
    A hologram is a light field captured onto a film. These live displays are usually just some sort of optical illusion. A real hologram shows you the actual light from the captured event as it’s the entire light field from the event. So your eyes are receiving essentially stored light.
    • dTal 7y ago
      Right there with you friend, but unfortunately that's not how language works and there's no hard line as to what is and isn't a "hologram". Yes, you can coherently capture a real light wave field directly onto photo-material - you can also generate one synthetically, quantize your light field into spatial "hogels", eliminate an axis of parallax, constrict the FOV etc, and finally replace your interference-based "hogels" with lenses and you have an integral image or lenticular, which is different physics but exactly the same imaging principles. Every one of those stages is a "hologram" to some set of people - hardcore holographers might draw the line at analog techniques, researchers will accept anything interference-based, and laypeople will slap the label on just about anything that looks cool. Believe me - this isn't a battle worth fighting. At the end of the day, everything is an illusion. Vision is not reality. Source: many a long year making digital holograms and trying to explain to people what it is I do.
• deleted 7y ago
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