As the author of this Engaget review notes, CNN's holograms during the election seemed completely gratuitous. Here's how the technology works:
On the subject's side:
• 35 HD cameras pointed at the subject in a ring
• Different cameras shoot at different angles (like the matrix), to transmit the entire body image
• The cameras are hooked up to the cameras in home base in NY, synchronizing the angles so perspective is right
• The system is set up in trailers outside Obama and McCain HQ
• Not only is it mechanical tracking via camera communication, there's infrared as well
• Correspondents see a 37-inch plasma where the return feed of the combined images are fed back to them. Useful for a misplaced hair or an unseemly boogar
• Twenty "computers" are crunching this data in order to make it usable
On the HQ side:
• Only used on two out of 40-something total camera feeds that CNN has
• Wolf Blitzer really loves it (or loves Jessica Yellin):
Here's the Will I Am Hologram.
What is crazy about this is that Will I Am is in the midst of one of the most exciting crowds of people ever - on the inauguration grounds in Chicago - and he's totally insulated by the holo shooting room - giving none of the excitement of actually being there, for the sake of being projected somewhere else. Weird.
Here's an interview about how it's done: