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Session: |
Showcase IV |
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Title: |
Contextual Backgrounds: AG on the Beach |
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Chair: |
Jennifer Teig von Hoffman (Boston University) |
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Time: |
Thursday, November 20, 3:30PM - 3:45PM |
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Rm #: |
6-10 |
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Speaker(s)/Author(s): |
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Darran Edmundson (ANU Supercomputer Facility Vizlab) |
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Description: |
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Green and blue screen compositing is widely used in television and film to merge foreground actors with background scenes. A classic example is the television weather report in which the otherwise information-less pixels surrounding the reporter's "talking head" are replaced by real data in the form of weather maps and images. The Access Grid, with wall display real-estate being a precious commodity, is particularly well suited to this technique. Users can be combined with their data in meaningful ways to aid understanding for remote viewers. Additionally, with multiple cameras in play, replacing each camera's background with a perspective-correct view of the virtual background helps to unify the otherwise disjoint streams coming from a node.
Fair enough, so why not paint one's Access Grid green and be done with it? Because while the end result is compelling, green screen studios are not at all pleasant environments. They require large sets to minimize color spill from the screen onto the actors plus highly-controlled lighting to ensure even screen color for automated keying. In contrast, the Access Grid - where the distinction between participant and viewer is highly blurred - needs to be a comfortable space conducive to multi-way communication. (Regardless, our small 6m x 4.5m retrofitted room precluded any thought of traditional green screening).
By covering the walls of our AG Node with a 3M retroreflective material and placing rings of illuminating green LEDs around our camera lenses, viewers at other nodes perceive brilliant green backgrounds in all outgoing video streams. (Users in the node itself perceive the walls to have a shimmering blue color.) However, prior to transmitting, we use software and hardware to remove the chroma green and, as we know the current position and orientation of the camera lense, composite camera-correct background images into the outgoing video stream. The result, at least for viewers at other nodes, is that our node participants appear embedded in a virtual world of our choosing. Allowing remote operation of our pan/tilt cameras helps to complete the illusion. In this showcase we demonstrate the technology with both scientific user background data and the more contrived example alluded to in the showcase title - namely, our node attendees in landlocked Canberra placed on a beautiful Australian beach.
A Windows Media Stream archive of this session is available at mms://winmedia.internet2.edu/VB-on-Demand/AGBeach.asf. It is recommended that this file be viewed using Windows Media Player version 9. |
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Link: |
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