Panasonic AG-HMX100 3D Production Post White Paper - Page 2

Depth and Scale Effects Along with the limitations noted above, simulated 3D offers some valuable tradeoffs. In addition to the opportunity to use most of the creative effects that are familiar to 2D filmmaking (among them: color effects, lens distortions, and a wide depth-of-field), 3D filmmakers gain the opportunity to exploit depth and scale effects that are unique to the 3D medium. By choosing a wide I/O or interocular-the horizontal displacement between their lenses-3D filmmakers are able to lend depth to objects that lie beyond the stereoscopic limit-objects that otherwise would appear to be flat. And, by significantly widening or narrowing the I/O, filmmakers can diminish or exaggerate the apparent size of objects-a consequence of the fact that the fixed interocular of the human eye-about 2.5" in the average adult-is the primary frame of reference that viewers use to evaluate the depth and size of objects they see in the world. Scenes shot with a narrow I/O display the effects hypostereo; scenes shot with a wide I/O display the effects of hyperstereo; and scenes shot with an average I/O (scenes which most closely replicate the scale of objects in the real world), are said to be in orthostereo. Strong degrees of convergence can also introduce significant scale effects. Familiar objects that are placed by the filmmaker far beyond the screen plane may seem gigantic relative to the size of the screen, while the same objects, when placed far in front of the screen, may appear miniaturized relative to the size of the screen. In addition, by strongly converging their lenses, 3D filmmakers can cause the spatial geometry of a scene to seem to warp, as if the space were bending toward or away from the viewer. Effects such as these, though unwanted in productions that aim to portray the world as it is, can be useful tools for a filmmaker producing a surrealistic or fantasy film. With its unique capabilities, 3D is not merely a tool for adding verisimilitude to a film-a way to persuade audiences that they are "there." It is, instead, a medium that offers filmmakers an opportunity to communicate with their audiences on a richer, more compelling level than was afforded to them in 2D. When skillfully employed, the artifacts that are peculiar to simulated 3D-instead of being clever gimmicks or awkward limitations-can be powerful tools that creative filmmakers can use to tell effective stories. Interocular and Convergence In addition to the variables to consider when capturing images in 2D (among them, focal length, focus, aperture, shutter angle, imager size, dynamic range, codec, colorspace, and frame rate) two important new options are available to 3D filmmakers: 1) the ability to adjust the interocular, or displacement, between their lenses and 2) the ability to adjust the convergence of the lenses. The term convergence, as it applies in 3D imaging, refers to the rotation, or toeingin, of the lenses of the two cameras in the 3D rig. The location of the point of convergence-the point where the optical axes of the lenses cross-determines the separation at the screen plane between the two components of the stereoscopic image pair. This separation, which is termed parallax, determines the apparent location in space of the 3D objects in the film relative to the screen plane. Fig.2 - I/O and Convergence 2