Every time I go out with my camera rig I get asked the same question: “why do you have so many cameras?”.
The answer is actually somewhat complicated. A 3D motion picture is created with two cameras and each camera’s image is presented discretely to each eye by the use of polarized filters or in the case of home 3D capable TV’s they would be shutter glasses in many cases.
If you want glasses-free 3D viewing then the ability to discretely show a single image to each eye is more difficult. And if you can move while looking at the photograph then something weird happens. Try this at your next 3D movie! Get up and walk around while looking at the 3D movie. The images follow you around because your perspective in space is fixed. It is a very weird sensation.
If you aren’t fixed to a chair and are walking around then you have a constantly changing perspective in real life. Holograms provide a pure seamless array of perspectives. A fantastic feature but as I have mentioned elsewhere on this site, holograms are very limited in terms of the pictures you can take and do not have real world colors or any color accuracy at this point in development. A lenticular lens array approach makes it possible to direct different images to each eye (that’s what the lens on the print overlay does). The smoothness of transition from one perspective to the next is a direct function of the number of cameras you have. More cameras provide a smoother transition from perspective to perspective. As you look at a lenticular and move, you see a change in perspective that can compare to what you see in real life. (In my photographs, I take great pains to make sure that is the case – but practically everyone else does not consider this important). If you are going for an effect then I suppose it isn’t important. But if you are trying to emulate reality then it is extremely important.
Providing the experience of multiple perspectives greatly enhances the realism of a 3D image and why I believe the 2 perspective approach used at the movies will eventually go away as it is more limiting.
Want to know more? Comment with questions and I’ll be glad to tell you what I have found out and experienced through trial and error.