in Video Digerati
What is Stereoscopy? Since I live in Las Vegas, I’d wager a healthy bet that we’ve all seen a 3D movie at some point in our lives. And I’m sure we’ve wondered how it works while we’re wearing those funny cardboard (or, if you’re at a theme park, they might be plastic) glasses.
As more and more movies are being created in 3D, and 3D is beginning to make its way into the home theatre market as well, I thought I would take the pulse of where media servers geared for live entertainment stand in this area of digital content. Here’s a brief overview of some of the products available that feature this exciting digital technology.
Before we begin, understand that there are a few different ways content creators can choose to give depth to objects on a flat screen: active, passive and anaglyph.
An active shutter 3D system works by presenting an image intended for the left eye while blocking the right eye's view, then presenting the right-eye image while blocking the left eye, and repeating this so rapidly the brain perceives only a single 3D image. The viewer wears special glasses that are capable of blacking out alternating eyes to achieve this effect.
To present stereoscopic pictures, two images are projected so that they are superimposed onto the same screen through either linear or circular polarizing filters. The 3D effect is created by having the viewer wear glasses that contain a pair of opposite polarizing filters. Since each filter only allows light that is similarly polarized to pass through, each eye subsequently sees only one of the images, and the brain perceives this as 3D.
Anaglyph is the old-school way of creating the illusion of 3D onscreen in movies. Viewers wear glasses with two complementary color filters, i.e. red and cyan, one filter per each eye. The red filter passes only red wavelength, while the cyan filter blocks red, passing the blue and green wavelengths. The viewer’s brain then interprets this information as a 3D image.
It’s also important to note as well that in order to create a 3D stereoscopic image, two projectors must be used, and special stereoscopic filters will need to be added to the projectors. Special projection screen materials are also necessary in most cases as well.
Media Servers with 3D stereoscopy playback capability include Watchout from Dataton (dataton.com/watchout) and Pandoras Box by coolux (coolux.de). Both have full DMX control capability and stand-alone interfaces, making them extremely powerful and applicable to a wider range of applications while also allowing them to be controlled via a DMX lighting console.
Playing a 3D stereoscopic movie within Watchout requires that two video files specially created using a stereoscopic camera (or even two cameras) are played back simultaneously while overlapping to create the 3D image. Since Watchout’s pre-split feature works for still images, all video content has to be pre-split into two separate files using an editing program like Final Cut Pro or After Effects. Each file created then contains the part of the image to be shown to either the left or right eye. For example, a file with the name “MyMovie.mov” could be split into two movies labeled “MyMovieLeft.mov” and “MyMovieRight.mov.” And since there are always two projectors needed to create a stereoscopic image, the user will actually be creating four files — two for projector 1 (left and right eyes) and two for projector 2. Once these files exist, the user loads them into the media server and turns on the Stereoscopic setting in the Media Menu. The processor then combines the separate files as one big image.
Controllable 3D Image Attributes
Within Watchout, if the content being played is a still image or small video, it may be possible to create a 3D type of playback effect simply by using some of Watchout’s built in 3D features. For instance, images can be adjusted via Z (Depth) so that they appear closer or at a distance. Additional controls for 3D images include Vanishing Point, Perspective, and Eye Distance. If the content is a 3D movie, though, it will have to be split and rendered as described above before it can be played be correctly.
Pandoras Box from coolus also allows S3D content to be played using both outputs from the media server. Like Watchout, the appropriately rendered content as well as polarized filters on the projection devices and glasses are required for viewing. Unlike Watchout, however, Pandoras Box allows for Anaglyph projection to be used with the old-school red and blue glasses. In terms of programming, the content for the left eye will be assigned to a layer and the content for the right eye will be assigned to a second layer. Using some simple adjustments to the Layer Opacity, ColorFX and VideoFX channels for each layer, the resulting image will be a stereoscopic image that is viewable on a single display device (with the glasses on, of course). And again, the DMX functionality of the Pandoras Box means that this can be programmed into a cue on a console.
What a long way we lighting programmers have come from the days of PAR cans and ACLs!
If you’d like to experiment with S3D projection, high resolution stock content is available from content providers like Artbeats (artbeats.com/footage/s3d). Then fit your projection devices with the right filters, buy some funny looking glasses, and get ready to pass the popcorn bowl!