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Well what CNN did was NOT a hologram, it was a GREEN SCREEN projection. Wolf Blitzer was NOT seeing a person in his studio as he would have if it was real Hologram, he was IMAGINING someone standing on that big red dot and looking 5 feet up from that spot.
What CNN actually did was tomogram, where images of the subject are captured from all sides, reconstructed by computers, then displayed on screen. Holograms, on the other hand, are projected into space.
Here's what CNN telecasted on TV
And below is a video where John Chambers of Cisco explaining the general concept of how Hologram works.