Not since Princess Leia begged Obi-Wan for help have holograms been the focus of so much attention, but Tupac’s return to the stage in supposedly holographic form has piqued interest in the 3-D illusionary once again. Unfortunately for everyone hoping holograms would emerge as the new Skype, the appearance of Tupac at Coachella had nothing to do with hologram technology.
San Diego-based AV Concepts created the lifelike Shakur using a technique called “Pepper’s Ghost.” Customized by British chemist John Pepper for use in the theater in the 19th century, the technology uses a hidden room and large piece of glass to create the clever illusion.
The International Business Times also has a handy graphic illustrating how Pepper’s Ghost works:
Full explanation of how it works at Arstechnica.
The scoop on science.