The technology used to produce Tupac's appearance is similar to the projection system that gave "life" to Japanese pop star Hatsune Miku, who became a "virtual" pop star in that country. This projection system, called "Musion Eyeliner," was developed by Dimensional Studios. It has been used previously for a variety of events, such as the Grammy Awards and Al Gore’s “Live Earth.”
That's the technology, however, but it was AV Concepts, a San Diego company, that created the hologram. Nick Smith, president of the company, said it was all Dr. Dre's idea.
"We worked with Dr. Dre on this and it was Dre's vision to bring this back to life. It was his idea from the very beginning and we worked with him and his camp to utilize the technology to make it come to life."
As you might expect in a world where a Bronx Zoo Cobra and a Washington State grizzly get their own Twitter accounts, the Holographic Tupac now has one, as well. It has over 8,000 followers, but as Hologram Tupac Tweeted, "Holo Pac don't follow nobody."
The performance capped off the first weekend of Coachella 2012. A holographic cameo had been expected, as rumors had leaked a few days before. The video of Tupac's appearance is embedded below.