Installation Profile: Shedding Light on Franklin
Mar 1, 2009 12:00 PM, By Trevor Boyer
Sophisticated networked systems illuminate museum's rotunda.
Around the rotunda's ledge, the four installed projectors beam content across the rotunda to acoustical panels on the opposite side. The institute is protective of aesthetics, so all technology had to be hidden as much as possible. That's one reason why the acoustical panels, which are the same color as the marble, double as projection screens. The ledge provided a way to mount AV gear inconspicuously, but at only 30in. deep, it required a proper safety harness system — which consumed about 12in. That left 18in. to fit a projector that needed to throw light about 80ft. across and 10ft. down.
A compact projector would not do the job, and a larger projector would hang past the edge of the ledge. So McCann Systems designed an assembly that puts a three-chip DLP projector on its side — its smallest surface — and in portrait mode. The projector beams light at a mirror that's angled at 45 degrees, so the image turns 90 degrees and reaches the opposite side of the rotunda in portrait mode. (rp Visual Solutions supplied four custom mirror mounts.) Nicholas Fazio, project manager for McCann Systems, estimates that the mirrors absorb approximately 8 percent of the projectors' light.
When it came time to choose a projector, brightness was the primary consideration. After demos, it became clear that 8000 lumens would be enough projector, but not overkill. The projector also had to fit the space and accept the mirroring assembly. Eventually, McCann's team and the museum staff decided on the Christie Digital Systems HD8K.
The projectors weigh 80lbs. each without their 4.1-6.9:1 lenses, so McCann had to study the ledge to ensure it would support two service people, the projectors, the loudspeakers (from audio-integration firm Visual Sound of Philadelphia), and the lights. An equipment elevator was installed within an intricate scaffolding system that allowed cleaners to access every surface of the dome.
After contractors removed the tapered portion of the scaffolding, contractors had a little more than a week to install the AV equipment on the ledge. While the scaffolding reached the ledge, they could not calibrate the projectors until the scaffolding was lowered even farther.
Like all projectors in its class, the HD8K is addressable via an IP network. McCann Systems ran two Cat-5e cables to each of the four projectors, one for video and one for control. Pulling cable wasn't as difficult as it could have been.
“Because it's a historic space, they didn't want to cut into the marble,” Fazio says. Luckily, however, there was excess electrical infrastructure within the rotunda. Using existing conduit, McCann installers substituted Cat-5e and other cables for the old electrical cable.
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