Q&A With Adam Neale, 7thSense
As immersive AV goes mainstream, the job of serving intricate, high-resolution media to nontraditional surfaces (curved screens, domes, globes) becomes a challenge. In October, Chicago's Museum of Science and Industry opened an exhibit called You! The Experience with a 13-foot-tall virtual heart. High-end projectors and four media servers from British AV specialist 7thSense make the magic happen. 7thSense director Adam Neale explains.
ADAM NEALE: As immersive AV goes mainstream, the job of serving intricate, high-resolution media to nontraditional surfaces (curved screens, domes, globes) becomes a challenge. In October, Chicago's Museum of Science and Industry opened an exhibit called You! The Experience with a 13-foot-tall virtual heart. High-end projectors and four media servers from British AV specialist 7thSense make the magic happen. 7thSense director Adam Neale explains.
PRO AV: Tell us about 7thSense.
NEALE: 7thSense's founders are both engineers, having come from a high-end flight simulation displays background where we developed multichannel display systems and supporting image processors. Our primary product, Delta, is a PC-based solution that can be an alternative to traditional fixed-role AV technology because it can serve content (often beyond HD resolution), provide distortion correction and blending, as well as some show control functionality.
PRO AV: How were you brought into the Giant Heart project? Have you done stuff like this before?
NEALE: We initially discussed the project with the heart's San Francisco-based integrator BBI Engineering in 2008 while working with them on the California Academy of Sciences. We've provided media serving for many full domes, partial domes, and flat-screen display systems. We also did a live event in Las Vegas that had a 100-foot-wide taco shell-shaped screen and15 projectors. The heart is also a formed screen surface, so it was a natural fit.
PRO AV: How does it work?
NEALE: The Giant Heart has a custom, perforated-steel 3D mesh as its front-projection surface with a traditional rear-projection screen behind it that's invisible in front-projection-only mode. Front projection uses five high-resolution projectors, three Projectiondesign F22s, and two F12s, which provide the animation for four external views of a heart. The rear-projection screen, using two F22 projectors, shows a set of four animated views of the inside of the heart. The imagery pulses in time to surround-sound audio to accurately represent a human heartbeat. The Giant Heart control system defaults to the external view, but the visitor, through BBI's touchscreen interface, can choose from a number of preset selections. They also have a slider on the touchscreen that gives them control over internal
versus external views. But arguably the coolest feature is that the system can measure the heart rate of the visitor and control the speed of the animations so the Giant Heart beats in time with the visitor's.
PRO AV: What was challenging about the project?
NEALE: First we had a 3D physical screen surface and multiple projectors that had to be brought to a single seamless image. The media server had to know about the 3D mesh shape and provide full distortion correction and blending. Second was having the visitor's heartbeat, through a sensor by Life Systems, dynamically alter the movie playback rate in sync. Most media servers are designed for 24-, 25-, or 30-frames-per-second playback. Ours is also a fixed-rate media server, so variable rate playback had to be engineered into the solution. Finally, because of the many views, we had to make it so very high-resolution movies could be swapped smoothly to provide an interactive fade between internal and external views of the heart.
PRO AV: Why use four media servers for the project?
NEALE: We wanted to maintain maximum image quality throughout the entire signal path, which meant driving all projectors at their native resolution. Each of the three front-projection servers plays a very high-resolution movie—4,000 pixels tall. To have two movies streaming at the same time and cross fade between them would have meant a demanding total pixel count. First we developed a way for the internal movie file caching mechanism to smoothly change from one disk location to another and swap out the movies instantly. Because we thought this might be too abrupt visually, we also engineered a sequence controller. Using a low-resolution copy of the movie, which plays simultaneously, but hidden, the sequencer fades the high-res movie to the low-res version, swaps out the high-res while it's hidden, then fades to the new high-res movie. The end result is a very smooth fade from one hi-res movie to another.