The latest resurgence in 3D has been driven by two significant developments in the theatrical arena: IMAX 3D and digital 3D. Movies can, and often are, simultaneously released in all of these different 3D formats, depending on the needs of each venue.

IMAX has produced specialty IMAX 3D nature documentaries and short fiction films since the mid-1980's. Recently, IMAX has also branched out to exhibit 3D versions of mainstream Hollywood movies. The Polar Express was a big hit in 2004. The IMAX 3D version continued to play months after the 2D version left theaters. The Ant Bully and Open Season followed.

In contrast to traditional IMAX, most digital 3D theaters display stereostopic imagery from a single digital projector. Although it's not the only option, the largest player in the digital 3D market is RealD playback system. RealD projectors are fitted with a liquid crystal screen in front of the lens, which alternately projects the right-eye and left-eye imagery. Viewers wear circularly polarized glasses that are not unlike previous 3D formats but allow for head-tilting movement without losing the three-dimensional effect. Viewers are often allowed to take the RealD glasses home afterwards, even though the glasses have limited usefulness outside a 3D theater.

In the last few years studios have released numerous feature films (mainly animated) in 3D. These include Coraline, Monsters vs. Aliens, the Robert Zemeckis adaptations of Beowulf and A Christmas Carol and Toy Story 3. Lately, it's getting difficult to find an animated movie that isn't in 3D! Digital productions such as the Hannah Montana and Miley Cyrus: Best of Both Worlds Concert and Journey to the Center of the Earth also demonstrated that live action works equally well in 3D.

Then came Avatar. James Cameron's mega-blockbuster proved indisputably that 3D is a force to be reckoned with. The movie shattered box-office records to become the highest grossing film of all time, and more of that came from 3D theaters than 2D. Even viewers who'd normally wait for home video flocked to theaters to see Avatar in 3D. And then they went back to see it again and again. Ever since that success, Hollywood studios have eagerly jumped on the 3D bandwagon. They've rushed new 3D features into production, and have even begun converting 2D movies into 3D.

A 3D renaissance is upon us and, unlike past 3D movements, this one looks like it's here to stay.