HD and Stereoscopic Film Production

C-T-S.com in addition to providing High Definition films can also provide more complicated Stereoscopic 3D filming production. Filmmakers were using these techniques as far back as the 1950s, although fairly unsuccessfully. Since the advent of digital production techniques however (digital capturing, post-production, and projection) we are able to create images with far more precision that avoid the eyestrain and headaches of earlier analogue attempts.

So how does this technology work? When a human views the world we get two different images into each of our eyes. This difference is defined by the different positions of the two eyes. The distance is usually 65mm for men, 63mm for women and less for children who average 51mm. If we average this distance we have 64mm. This distance is called the average human interoccular distance and without it we would have no stereo 3D effect.

In terms of filming, any camera can be used although we do need to use specialized software for post production. Basically two cameras record the same scene, side by side on a parallel bar a set distance apart. The relative angles of the cameras during shooting, as well as the separation between the images as they are combined in post production show depth when viewed through cyan and amber glasses thus giving the 3D effect.

While most of the industry agrees strongly over most of the science involved in 3D imaging, there is one remarkably important point that divides the community: Should the two primary cameras, when set correctly at 64mm apart, look straight ahead or point slightly towards each other? Our eyes converge so logically shouldn’t the cameras? As it turns out, both approaches work and that if both cameras look straight ahead or are in parallel, you can easily adjust the resulting images in post production. A simple left and right shift on one of the cameras will overlap the images and produce a stereo effect.

When displaying 3D, early systems required two projectors, which lead to unreliable results and thus a poor audience experience. With the invention of the “Z-Screen” which is the basis of the single projector REAL D system, the Z-Screen sits in front of a DLP digital projector and a modulator switches the characteristics of the polarized light at high speed. The Z-Screen is made up of a linear polarizer and two pi-cels in the optical path. The pi-cells switch on and off to create left and right handled circarly polarized light in sync with the left and right eye images. The system requires a silver screen to be used in the cinema and the audience to wear polarizing glasses.

It is much easier to create artificial stereo with fully animated 3D footage, as a second camera can be placed in virtual space a nominal constant distance from the original camera. On average this second render would only add 10-15% more time compared to rendering with just one camera.