Tron. wow. it was incredible what they had to do in order to get the look they were after with the live action scenes that were supposed to be taking place inside the computer. It was done with back light compositing which while I understood it on a very basic level, it really impressed me with what they did. every frame had to be treated the same, for the entire 75 minutes of film that needed to be worked on. 24 frames a second * anywhere from 7 to 30 layers per frame * 60 seconds per minute * 75 minutes. a ton of frames had to be worked on, almost making it like and old school animated disney movie. I'm sorry if this doesn't make sense. even watching the making of as I type now and still its so much to comprehend it's mind blowing.
1) shoot the scenes on 70mm black and white film (hence the post in this forum).
2) blow up every frame to a 12x20 inch neg using two photo-rotoscope machines.
3) those frames are put through a processor to make hi-con positives and negatives. this was a special custom film made by kodak just for this movie and apparently was never made by kodak again.
4) the number of hi-con positives and negs that where made depended on what was going on in the scene. at the most basic frame for example of a live action character, , a minimum of 5 negs and pos's had to be made. 1 for the main body of the character, 1 for the glowing circuits on their costume, 1 for the whites of their actors eyes and for their teeth, and 1 other for special contrast facial features. these where the masks that where made to use to get the desired effect
5) then each one of the above mentioned frames, as above the 5 basic character frames had to be photographed individually. The director said the thinnest frame had 7 layers stacked for the most basic scene while the most complex scenes had 30 layers.
6) every frames was then put into an animation camera to create cells of each layer
7) every cell was then sent to taiwan to have them do inking and painting. remember each original frame had between 7 and 30 cells in it.
8) the finished cells where then sent back to disney. they were put on light boxes so they could be finally stacked and photographed one frame at a time.
at that point they then assembled the film and edited asyou would edit a normal film. It doesn't read great but watching them describe it and seeing some actual frames, layers and cells, it was the coolest thing. If you haven't seen it, go rent or get a copy of the new tron blu ray release and watch the extras on the making of tron. You will be amazed at what they did. I know when i watch the film again last night I watched in a totally different way.