Eazy-E and Ol' Dirty Bastard have not been with us since 1995 and 2004, respectively. But that didn't stop Chang Weisberg and the other promoters of Rock the Bells from wanting them both to appear as part of this year's ineup. But how would they pull off such a feat? You can find out in this new behind-the-scenes video, which details the meticulous process of bringing these two legends back for all four stops of this year's festival.

Teaming up with the crew from AV Concepts--who famously created the Tupac hologram that "performed" at Coachella in 2012--Chang and his crew from Guerrilla Union set about creating "original virtual performances" by ODB and Eazy using facial capture technology. Luckily for them, they had the perfect real life models to base the rappers' simulated facial and body movements on: their own sons. That's right, Young Dirty Bastard and Eric "Lil Eazy-E" Wright, Jr. volunteered to emulate and recreate the personas and performance styles of their respective fathers, which were then used as the basis for this cutting-edge technology.

To learn more about how Guerrilla Union and AV Concepts pulled off this amazing achievement, click here. If you want to try and see it for yourself, then check @ComplexMag on Twitter and find the #RockTheBellsSF tweet. RT to enter for your chance to win two General Admission tickets for this weekend's Rock the Bells show in San Francisco. The festival is a truly amazing thing to experience in person. Just ask Easy and ODB.