What you need to know about hologram people

What you need to know about hologram people:

The aforementioned performances are a product of a centuries-old technique called "Pepper's Ghost." You might've seen this on a pretty grand scale during a family vacation to Disneyland, too. The park's Haunted Mansion ride uses it extensively, especially during the ballroom scene where "ghosts" are dancing all over the place. The key difference between what we're seeing now and what's been used for the past few hundred years? The tech being used has gotten much more advanced.The likes of Princess Leia pleading for Obi-Wan's help. Holograms use an array of lights to project a 3D image that's viewable from all sides. What we're seeing now is more of a parlor trick involving some figurative smoke and literal mirrors. Why it seems that no one much cared about any of this before the dead were involved, though, isn't exactly clear -- especially when one of the key companies behind the recent craze, Dimensional Studios, is responsible for basically all of the performances you're familiar with. Its work dates back to Madonna performing with Gorillaz at the Grammy awards in 2006, and Al Gore speaking in Tokyo at 2007's Live Earth concert.

HOW DOES IT WORK?

The holographic people we've seen are based off of an illusion called "Pepper's Ghost," developed by Henry Dircks and John Pepper in 1863. The concept requires two rooms, some specifically placed glass and carefully controlled lighting. A room adjacent to the viewing area (or stage) is set up as a mirror-image of the area the audience sees; if there's a chair on the right of the stage, it's on the left in the other room. The key difference is that other room is either painted black or entirely unlit, so as not to cast any unwanted reflections that would break the suspension of disbelief. That room is where the performer resides. The stage area must be brightly lit at first for the whole thing to work. Then, the stage's lights are dimmed slightly and the lights are raised in the mirror-image room, which causes the not-physical performer to appear.