Two days ago I watched the 2010 remake of
Clash of the Titans, in 3D. I'm not going to rave about how entertaining the remake was, though it was a fun ride for the modern (and more shallow) audience. I'm posting because I found out after that the film was not shot in 3D originally, but converted as an afterthought to ride on the popularity of the stereoscopy bandwagon popularized by the recent success of
Avatar 3D.
Now,
Avatar was designed to be a 3D experience from the start, therefore the actors were filmed using a camera rig with two lenses side by side, each recording a slightly different angle of the scene. When these left and right images are filtered by 3D glasses into our left and right eyes separately in the cinema, our brain combines them into a single coherent view with the perception of depth.
3D ConversionA 3D converted movie is a whole different story. With the original footage being totally flat, artists have to fabricate the depth information from scratch. That wouldn't be so hard in the case of a CG movie, since everything already exists as 3D data, so the movie could be re-rendered using two offset CG cameras. Theoretically, any scene with CGI creatures and effects should be relatively easy to convert into stereoscopic 3D. But what about the live-action?
Well, the artists doing the conversion would have to re-create all the objects that need to have depth in the scene using 3D software, then project the original footage onto the 3D models so that a second eye's view of the scene can be recorded. Of course this is just one of the tricks that can be applied, but that alone is so painstaking that it would make rotoscoping seem like a walk in the park in comparison.
My Conversion ExperimentTo get a sense of how tough it is, I tried doing a little 3D conversion of my own. I googled for an image from the 1981
Clash of the Titans, loaded it into Photoshop and created a stereo pair using a simple offsetting trick. The technique is simple (anyone who knows how binocular vision works should be able to figure it out) so I will not elaborate here. Maybe I'll do some more explanation in a future post.
Anyway, to get the 3D effect with the following, you need to cross your eyes so that the two images coincide. The image on the left is the original, and the image of the right was edited in Photoshop to create a left-eye view for the stereo pair.
3D stereoscopic pair of a scene from Clash of the Titans (1981)
Click image to view at original size.This was a quick and dirty job done in a couple of hours. The 3D effect is cheesy, but the depth perception definitely works. I shudder at the thought of converting an entire 2 hour movie at 24 frames per second.
AfterthoughtsTo make a stereoscopic movie, 3D conversion will never beat shooting in 3D in the first place. Many converted movies end up looking shallow and fake. Stereoscopy also forces some of the tried-and-tested cinematography rules out the window, lest you want your viewers to feel dizzy, but that's not stopping the producers of
Alice in Wonderland, Iron Man 2 and others from the 3D conversion craze.
