Information AboutFulldome |
| CATEGORIES ABOUT FULLDOME | |
| film and video technology | |
| art media | |
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Although the current technology emerged in the early-to-mid 1990s , fulldome environments have evolved from numerous influences, including immersive art and storytelling, with technological roots in Domed Architecture , Planetarium s, multi-projector film environments, Flight Simulation , and Virtual Reality . Initial approaches to moving fulldome imagery used wide-angle lenses, both 35 and 70 mm Filmstock , but the expense and ungainly nature of the film medium prevented much progress; furthermore, film formats such as Omnimax did not cover the full two pi Steradian s of the dome surface, leaving a section of the dome blank (though, due to seating arrangements, that part of the dome was not seen by most viewers). Later approaches to fulldome utilized monochromatic Vector Graphics Systems projected through a fisheye lens. Contemporary configurations employ raster Video Projectors , either singly or grouped together to cover the dome surface with full-color images and animations. FULLDOME VIDEO TECHNOLOGY Fulldome video projection can use a variety of technologies in two typical formats: single- and multiple-projector systems. The individual projector(s) can be driven by a variety of video sources, typically feeding material rendered in either real-time or “pre-rendered” modes. The end result is a video image that covers an entire domed projection surface, yielding an immersive experience that fills a viewer’s field of view. Single- versus Multiple-Projector Systems Single-projector fulldome video systems use a single (or muxed) video source displayed through a single fisheye lens, typically located at or near the center of a hemispherical projection surface. A single projector has the benefit of avoiding edge blends (see below) between multiple projectors. A disadvantage of central projectors is the loss of the center of the dome for optimal viewing of the reconstructed perspective view provided by true hemispheric projection, a problem shared with traditional Planetarium projectors. High quality hemispheric projection lenses are very expensive and operate at the practical limits of optical performance needed for high resolution full dome coverage. Multiple-projector fulldome video systems rely on two or more video projectors edge-blended to create a seamless image that covers a hemispherical projection surface; splitting the entire image up into segments allows for higher-resolution imagery and projector placement that does not intrude on the viewing area underneath the dome. A disadvantage of multiple projection is the need to frequently adjust the alignment of projectors and the uneven aging of separate projectors leading to brightness differences between segments. Even minor performance differences between projectors can be obvious whan projecting a solid color across the entire scene. Common Video Projector Technology A wide variety of video projection technologies has been employed in domes, including Cathode Ray Tube (CRT) , Digital Light Processing (DLP) , Liquid Crystal Display (LCD) , Liquid Crystal On Silicon (LCOS) , and most recently, two varieties of laser projectors (the Laser Video Projector entry describes one version of the technology). For multi-projector systems in particular, display devices must have a low Black Level (i.e., project little or no light when no signal is sent to them) to allow for reasonable edge-blending between the different projector footprints. Otherwise, overlapping video images will have an additive effect, causing a complex pattern of grey to appear even when no image is being projected. This becomes particularly important for users in the Planetarium field, who have a vested interest in projecting a dark night sky. The desire for projectors to “go to black” has resulted in continued use of CRT technology, even as newer and less expensive technologies have emerged. LCD projectors have fundamental limits on their ability to project true black as well as light, which has tended to limit their use in planetariums. LCOS and modified LCOS projectors have improved on LCD Contrast Ratio s while also eliminating the “screen door” effect of small gaps between LCD pixels. “Dark chip” DLP projectors improve on the standard DLP design and can offer relatively inexpensive solution with bright images, but the black level requires physical baffling of the projectors. As the technology matures and reduces in price, laser projection looks promising for dome projection as it offers bright images, large dynamic range and a very wide Color Space . LINKS TO FULLDOME RESOURCES Discussion Groups Events Tools and Tutorials
HISTORY Historic Influences Fulldome Video History FULLDOME APPLICATIONS Generally divided into real-time interactive computer graphics, pre-rendered computer graphics, live capture, and compositied. Examples of real-time applications
Examples of pre-rendered playback applications
Examples of real-time shows
Examples of pre-rendered movies
Art Installations
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