3D Cinema
RPM Associates Technical Consulting

The stereoscopic effect is an illusion produced by presenting slightly different images to the right and left eyes (as in the image above, which we used in developing our technology). This technique has now arrived in movie theaters, where special shutters in front of the projector present images using polarized light, with a different polarization state for the right and left images, transmitted very quickly one after the other. Your eyes aren’t sensitive to polarization, but special glasses that you wear during the movie allow only a specific polarization state to reach each eye. Bingo — 3D! One of the few companies involved in 3D cinema (you probably know who they are) contracted with us to work on several ideas related to 3D movies. One was to design a system that allows a 3D data stream to be transmitted over conventional channels. Since 3D movies have separate left/right images, they contain twice as much data as a regular movie. Although this is not a problem for most theaters, where movies are now delivered via hard drive shipments or over the Internet, it is a problem when transmitting live over bandwidth-limited channels. One such application that has become popular is viewing concerts and other live events at a local movie theater, in 3D. We enabled this by building a system that accepts a high-bandwidth 3D live video feed and compresses it into a form that can be transmitted over existing microwave or satellite channels. At the receiving end the images are reconstructed into left/right eye pairs for 3D viewing. One of the constraints on the technique is that the intermediate format still has to be suitable for standard MPEG compression — this eliminated any schemes that destroy the local spatial coherence of the images. The compression we implemented, while not lossless, relies on certain features of the human visual system to minimize the impact of the discarded information, and the end result is almost impossible to distinguish from the original.