Audience members wear special LCD shutter glasses to achieve the 3-D effect
network that provides the low latency and high throughput link required by graphic data distribution. The three rendering nodes generate a planar image. However, projecting such an image on a three-headed, rear-projection system using a cylindrical screen inherently leads to major geometrical distortions and edge management issues. For the Visualization lab, MUN chose to trust one of the leaders in the high-end imaging installations worldwide, the US-based Panoram Technologies. They provided the hardware and software that converts the PC SVGA output (as well as other sources, such as DVD / VHS video) into three sets of output signals that drive three Mirage 2000 DLP projectors to create one continuous, stereoscopic image on the screen. The three rendering nodes are in fact nothing more than wellequipped gaming-class PCs. They feature high-end video cards -- in this case, NVidia Quadro FX4500G -- which are capable of the outstanding graphics performance required by active stereo. The cards are sync-locked together to enable three-head active stereo. Their output is routed through a matrix switcher that allows the user to select multiple video / audio sources for use in the lab, and is then directed to two output groups: the main screen and the control monitors. The main screen streams are fed to three scan converters that bring the video signal to the native resolution of the three projectors (1280 x 1024 pixels each). Each channel is then routed through a
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PanoMaker V digital video processor that is programmed to adjust the image geometry so that the resulting image has no geometrical distortions on the cylindrical screen. The video processors also provide the edge management or blending -- gradually reducing the image brightness towards the adjacent borders so that the overlapping area is indistinguishable from the rest of each component image, and a seamless image is displayed across the large screen. The other output group, the control monitors, takes any available input signal and displays it on any of the four control monitors available to the laboratory operators, such that they can preview the next video segment during a session. The entire video processing chain is controlled by Panoram's proprietary software, Integrator 2000. It is widely known that the image depth perception is caused by the slight differences between the images perceived by each eye. Currently there are four main approaches to creating a three dimensional image. Anaglyph stereo uses red / green glasses to separate the components of a bi-color image. This method, although the only one available for prints, offers low quality, monochromatic images. Polarized light projection separates the two images overlapping on the screen using glasses that feature polarizer lens -- thus offering a full color image, but at a reduced brightness level. Stereoscopic monitors use an array of pixel-sized cylindrical lens built into the
Marine Technology Reporter 35
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