Shooting 3D Video And Animated Movies
To create the illusion of “being there,” and to give our brains the same vision of a scene that we would see if we were seeing the scene with our own eyes, a camera needs to record the scene that each eye would see separately. 3D cameras have two lenses, spaced several inches apart, aligned in parallel. Some 3D cameras use a single camera, and some use two cameras, each with its own lens in a 3D camera rig.
By recording and later displaying a separate image of the scene for each eye, 3D film and video systems can recreate the scene in a way that closely matches what we would see if our eyes were in the same place that the camera was when it recorded the scene.
The average “interocular distance” (spacing of the eyes) is about 2.5 inches. One important variable for 3D camera systems is the interocular distance. The further the spacing of each camera lens, the greater the 3D effect. Cameras set up with an interocular distance of 2.5 inches are said to be configured to be orthostereoscopic. This setup attempts to accurately replicate human vision.
Another important parameter is the angle of convergence. 3D camera lenses that are aligned in parallel will result in a picture where all objects appear to be in front of the TV screen (or display). Objects at an infinite distance will appear to be on the screen. To create a stronger 3D effect, camera lenses can be angled (converged) slightly inward. With this setup, objects at the distance where the optical axes of both lenses converge will later appear to be on the screen. Closer objects will appear in front of the screen, and farther objects will appear to be behind the screen. Cameras like the Panasonic AG-3DA1 (shown above) feature lenses that allow for the angle of convergence to be adjusted, to align to a distance that the videographer prefers.
3D animated movies are movies that are created using 3D object modeling software. This genre of movies was pioneered by Pixar with the movie Toy Story. Characters and scenery in the movie are generated as three-dimensional models. Of course, these movies are normally rendered to standard two-dimensional frames.
Modern computer games are created in a very similar fashion, but they are rendered in real-time as you play the game.
A big advantage of 3D animation is that it can also be rendered and viewed in 3D. To create a 3D version of the movie, the movie is rendered in two separate passes (one for each eye). For the second pass, the studio simply moves the virtual camera perspective 2.5 inches to one side, creating the video for the second eye. Though each frame of video can take hours to render (due to complexity), the cost of rendering a second perspective of a movie is small compared to the overall cost of creating the movie. For a good movie, the additional cost of creating a 3D version through a second rendering pass is modest compared to the benefits.