In 2010, many viewers learned the hard way that not all 3D is created equal. Avatar worked so well in 3D because the movie was photographed wish specially built digital 3D cameras. Animated films like How to Train Your Dragon and Shrek Forever After were likewise produced explicitly for 3D. Their animation was rendered in the 3D format from inception. In these movies, every shot was designed with 3D viewing in mind.

However, nowadays, it's also possible to convert a 2D movie into 3D after the fact using complex digital rendering techniques. This was first demonstrated on Tim Burton's The Nightmare Before Christmas, which was originally photographed in 2D stop-motion animation but has been re-released to selected theaters in the 3D format annually since 2006. For that movie, digital artists painstakingly worked to adjust each and every shot into a new 3D rendering. The results have been generally well received.

Unfortunately, not every 2D-to-3D conversion has worked out so well. After Avatar, a host of quickie 3D rush jobs were performed on movies never designed for 3D. Among these, Clash of the Titans and The Last Airbender stand out as the most notorious examples. In both cases, the theaterical 3D effects were unconvincing, murky and often headache inducing. Audiences felt cheated.

Unfortunately, for each new 3D movie released to theaters, the publicity and marketing materials rarely advertise the difference between real 3D and simulated 3D conversions. Confusion between the two, and the radically different quality that each delivers, has led to a growing dissatisfaction with 3D in general.

Hollywood wants 3D to succeed. Given the economic troubles of recent years and the downturn in theatrical attendance, Hollywood may even need 3D to succeed. With the advent of 3D HDTV's and Blu-ray hardware now available to the home theater market, the worldwide electronics industry is also banking on a continued consumer interest in 3D. But for 3D to prove viable in the long term, viewers must feel that they're getting something more than a gimmick. They need more movies that use 3D in an artistically purposeful way, as Avatar did, and fewer that smply try to cash in on the phenomenon with half-hearted and lackluster results. Otherwise, we may find that this latest 3D revival is just another fad that will eventually run out of steam.