A Work In Progress

Mar 1, 2001 12:00 PM, Eddie Ciletti

TWO EVENTS OCCURRED AROUND 1960, WHEN I WAS FIVE, THAT aroused my curiosity enough to inspire me for life. One was seeing my favorite cartoons on a color TV for the first time. The other was even more inspiring: My kindergarten class took a trip to Fels Planetarium at Philadelphia's Franklin Institute. Both of these events had a long-term impact on my life, played out as adolescent distractions and, later, career experimentation. Planetariums (and televisions) have improved so much since I was five that they are now almost unrecognizable as the same things. Today, I have found a calling and a challenge as a professional. In this industry, it is our turn to creatively apply new technology that will inspire the next generation of techno-enthusiasts and scientists.

Nowhere are strides in technology more apparent than at the American Museum of Natural History in New York. The recently added Frederick Phineas and Sandra Priest Rose Center for Earth and Space did far more than just increase the square footage of the AMNH by a total of 333,500 square feet (the equivalent of a major museum in its own right).

Aram Friedman is currently the director of engineering at the Rose Center. His video career spans the last 20 years, an exciting time for digital video and computer graphics. A recurring theme for Friedman is the application of new digital technology to an old analog process. As the technology matures, interface solutions are invented and adapted. The process requires incredible amounts of research. There are few experts, and the ink on whatever documentation exists isn't dry. The sidebar, How Fast is Fast?, is a brief overview of the various flavors of video that we have today.

Eddie Ciletti: How did you become part of the Rose Center project?

Aram Friedman: I had just finished designing an automation system for Nice Shoes. (The job was a great way for me to decompress after working on the MSNBC graphics facility.) Dennis Davidson (of AMNH) had seen flight simulation technology that, in his vision, could hopefully be applied to a planetarium star show in a way that allowed more versatility than a traditional star projector. The staff wrote a request for proposal. Potential vendors responded with thick books of documentation that no one at the museum had the skills to interpret. Dennis called me to translate. It took eight days!

Who are your people?

The Rose Center engineering staff consists of five video engineers, five Unix administrators and the senior engineers: Benji Bernhardt, Josh Minges and me. Anthony Braun is our staff producer and has been a long-term associate for our engineering projects. We also maintain a stable of freelance and part time engineering to cover the 24/7 operation.

Benji and you recently went to an electronic cinema conference held by the National Institute of Standards and Technology. What did you learn there?

We wanted to calibrate our understanding of the e-cinema technology. Mostly, we learned that e-cinema will not fly unless it can be as good as film, if not better. And, at the moment, movie theaters are not doing so well financially.

Who else do you work with?

Smokey Forester is the head of a production unit called Science Bulletins. He and his crew specialize in creating content for the museum the Hall of Planet Earth, the Astro Bulletins Wall and Bio Bulletins, in the Hall of Biodiversity. Basically, they were shooting NTSC that, after editing, would be heavily compressed so a server could deliver it. Together, we investigated HD technology.

What were the challenges in the beginning?

As I read through the documentation, I was inspired and determined to become part of the project. The challenge was to try to equalize all of the doable options ranging in projected cost from $2 million to $10 million to help them make a decision. At that time, no turnkey system (or systems integrator) existed. I suggested that they tackle the project in-house by hiring support specialists for each technological facet. They agreed and we started. It has been an incredible undertaking, and we're not finished yet!

This was just to realize the Digital Dome the Planetarium?

Designing an exhibition hall that will be capable of growing required us to consider not only what is possible at the moment but also what will be possible. Aram Friedman

Initially, yes. It was the first time museum personnel had daily access to an in-house engineering staff. They started asking us to do other things, a natural progression that led to our involvement beyond the planetarium.

What are some of the costs involved?

A public exhibition space has its own requirements, not the least of which is survival for a minimum of 30 years (hopefully, at least 50), so it's no surprise that the structure alone can cost between $10 million and $20 million. Designing an exhibition hall that will be capable of growing with changes in science and technology required us to consider not only what was possible at the moment and remember we started this almost three years ago but also what will be possible as technology matures.

How did you choose the equipment?

We contacted Fujitsu, Panasonic, Pioneer and Sony; and all provided us with their 42-inch plasma displays. It was a tall order because the flat-screen monitors were in such demand that we didn't have much time to test them. Before the evaluation could begin, we had to rent an HD camera and crew to record beauty shots around the city. We shot using 1080i, the only option at that time.

Understand that a plasma display is not capable of displaying all of HD's pixels. We learned that a good translation from 1080i to the native plasma format is key to appreciating and taking maximum advantage of the capabilities of the display. We chose Sony for its flexible interface and support, but we also have a 50-inch Pioneer display that has more pixels and is by far our premier screen for special events. I've also seen a 60-inch Panasonic that looks equally gorgeous. (All screen dimensions are diagonal based on a 16:9 aspect ratio.)

How is the reliability, and what problems have you had?

The 28 screens in the facility have been very reliable. We've lost a few a row or a column would fail all within the warranty period. Occasionally, rough transit causes an out-of-the-box failure. Since these are gas-discharge displays, we anticipate a time when they will get tired, but that hasn't happened yet.

What about the projectors, any preferences?

I can't endorse any one projector because there are many models and many applications. We use Barco for our special venues; they are modified for our purposes. I've seen a scanning laser projector that is beautiful and am hoping to bring it into the country.

Ultimately, you had to decide on a camera.

At the time we were looking at cameras, there were two options. Sony's camera had a built-in tape machine. Panasonic made a separate recorder for its camera. Both cameras looked great, but obviously the Sony was more convenient for documentary-style work. It also locked us into 1080i.

At first, we thought we had to catch up with the industry, but we ended up ahead in the sense that the various screens became our audience, hungry for content. In order to create that content, it was first necessary to build an HD editing and production facility, then decide on a server technology.

What was available?

Sierra Design Labs had a D-1 hard disk server. We discovered that Sony's 7:1 compression technology was available as a stand-alone encode/decode device. The Sierra is then connected to Telecast [www.telecast-fiber.com] fiber-optic transmission equipment feeding thousands of feet of fiber.

Where are these screens and how do you feed them?

Plasma displays are all over the building, at the entrance to every hall. The input options are NTSC, S-video, RGB, YUV and Y-Pb-Pr, which is component with tri-level sync. (In tri-level sync, the sync goes negative, then zero, then positive, then zero again.) We transmit HD serial digital over single-mode fiber, decoded using a D/A at each screen. D/A converters were expensive at first. Then, AJA [www.aja.com] came out with a converter the size of a cigarette pack for $2,000.

Now that all of the systems are installed, what is your primary responsibility?

The most important job is keeping the SKY theater (a.k.a. the Planetarium or Digital Dome) working. Next is providing support for all of the production processes. Third is developing new technology and new venues for the museum; we are a laboratory, of sorts.

How have things evolved since you started?

When we started, the available test and reference equipment was minimal compared to traditional video. We couldn't justify the $20,000 to $40,000 price tag for HD broadcast monitors. This is a closed system. We shoot component digital so the image is locked (unlike NTSC). Color correction is not necessary, and the productions will be viewed only on known monitors. Experience is teaching us what constitutes a good picture.

As for test equipment, Tektronix was traditionally my first choice, but their $30,000 scope didn't do what we wanted. Surprisingly, Leader made a scope for $15,000 that met most of our requirements.

What reference material was available?

I read all that I could get my hands on from SMPTE and the Advanced Television Systems Committee of the FCC. I also consulted the very few people around the city who had HD experience. Chuck Roback, chief engineer at Tape House, and Dave Satin at SMA video have the only two facilities with the Philips Spirit HD telecine (film-to-HD) converter.

How did you prepare for the Dome?

Diving into an emerging technology such as this, the first version of interface is analog, the second version is parallel digital and the third version is serial digital.

We experimented by building a conference room using a $15,000 Barco 808, 8-inch analog tube projector. Unlike plasma, the Barco has HD resolution. This became our lab, a $75,000 prototype. Our choice of resolution for the dome was 1,280 by 1,024 (5 by 4, or an aspect ratio of 1.25:1), 60-frame progressive.

Already this was a higher resolution and frame rate than HD supported; and the ONYX is capable of even more resolution, including a 72Hz frame rate. The additional power is for real-time 3-D imaging, the type that requires two signals (left eye, right eye) to be output simultaneously for viewing via crystal glasses. We don't do this (yet), but it serves as headroom.

On top of this, we had every kind of video source (RGB from PCs, Macs, the SGI Onyx and SGI 02 workstations), plus the usual analog formats (NTSC, S-video) from ABC and NASA's satellite feeds.

A patching nightmare!

Indeed! The search to integrate all the various flavors led to an industry that I knew little about A/V. I also discovered an 8?8 RGB analog routing switcher by Extron with 400MHz bandwidth per color channel. We also use a similar product from AutoPatch.

Diving into an emerging technology such as this, the first version of interface is analog, the second is parallel digital and the version is serial digital. In the case of the Dome, where the computer is located far away from the projectors, the analog 13W3 outputs of the 7-Pipe ONYX II super computer (183MHz bandwidth) feed a super-high bandwidth Lightwave routing switcher which then feeds a Lightwave fiber transmitter/receiver. [lw.pennnet.com]

What are the Dome's specs?

The dome is 21 meters (68 feet) across with seven projectors hidden in the wall at the horizon line. Five of the projectors are 72 apart, illuminating the panorama. Two more projectors criss-cross each other to illuminate the cap. We are also using a newer version of the Zeiss star projector. Projecting to a curved surface has its challenges, but it is also capable of generating 3-D effects without special glasses, equipment or source material.

What sort of challenges?

Projection to a dome is a unique situation. Our Barco 812 projector uses three 12-inch CRTs projecting 68 feet. It is not a matter of how bright, because projecting to a curved surface results in a phenomenon known as cross-reflective contamination. Too much light will bounce and scatter, reducing contrast. The dome is light-tight like a camera, and we are counting on people having night vision.

A CRT projector can achieve true black because it is possible to turn the guns off, unlike LCD or DLT projectors, where the back-light is always on and the screen can not block all of the light. A CRT has better contrast than solid-state chip projectors.

What is shown on the dome?

Our in-house computer graphics department has created an immersive environment for the Dome, simulating the Milky Way galaxy. A movie is stored on 14 Ciprico RAID drives. The data moves through the Onyx, which can render images in real time, then out to the projectors. When this hardware choice was made, there was no other device capable of real-time playback of that much data. We are about to put custom digital data recorders online to replace the Ciprico drives.

How does the curved surface affect adjusting convergence on projectors?

Ah! The CRT has a rubbery raster, so the convergence is mucked-up to compensate for the compound-curved surface, (both a horizontal and vertical curve). Using a test grid, everything looks perfectly aligned. It creates an illusion of 3-D that I can not describe; you have to come see it.

I'd love to. Do you have any closing comments?

Considering what's happened since I started in this business the transition from 2-inch quad to 1-inch, analog to digital, then linear to non-linear editing there seem to be several recurring themes. Twenty years ago, cameras were $100,000, and I watched as technologies improved while the size shrunk and the price decreased to $10,000. Now, HD cameras are $100,000 and the gear to do the processing and recording is equally expensive. As an engineer, this is good for me, but it won't last.

Whenever a change in technology occurs, the weak companies go out of business. The engineers make a good living for a while, and one group consistently never takes a hit: the content providers.

Oh yeah and you can't make assumptions.

What do you mean?

When ABC chose the 720P format for broadcast, we wondered why because there's less picture resolution but more frames (the latter is better for motion). Then, I coincidentally bought an iMac, and it came with a DVD drive and A Bug's Life. I was shocked. Even with all of the compression, viewing the DVD on a high-res progressive-scan computer monitor is amazing.

When we started, there was no 720P. The manufacturers based the 1080i spec on the maximum capability of the recorders. But, when the 1080i signal is down-converted for use on a plasma screen, it is dumped into a buffer and essentially becomes a progressive scan. Solid-state displays are not scanned. Once all the information is in the buffer, the display reads it all at once.

We always worked with tube projectors and tube monitors. At one point we compared an HD LCD projector against our HD tube projector. The LCD looked fabulous, but the tube showed all of the typical analog artifacts like ringing, plus the effects from interlacing. So, I learned not to make assumptions or be too rigid in my thinking.

Thank you for your time, Aram. I look forward to talking again. Maybe when the Science Museum of Minnesota sees this article you'll be coming here, and I can be your assistant!

It was indeed a pleasure. There is so much more to talk about; we really haven't scratched the surface. This conversation could continue for weeks. You know, if you lived here you'd have a job.

Eddie Ciletti spent 19 years chasing hums and buzzes in New York City. He now chases his son Luca in the Twin Cities area. Drop by www.tangible-technology.com for a virtual visit.

How Fast is Fast?

ANALOG AUDIO HAS A BANDWIDTH OF 20 KHZ. Digital audio requires 6 mHz of bandwidth just like analog video that's 300 times as much! The data rate of an audio CD is 1.4 mega-bits per second. Dividing by 8 bits turns that into 175 kilo-bytes per second. Basically, bandwidth is to analog as data rate is to digital. You will see that the bandwidth required for digital HD is astounding, putting heavy demands on cabling, connectors, patch bays and routing switchers (Belden 1505A co-ax, King 2025-51-9 connectors and Trompeter 1.5 gig patchbays, for example).

Imagine the jump from analog video to digital video. At 143 MB/s (4fsc NTSC) the data stream generated by 640?480 (displayed) pixels is a trickle compared to the deluge of pixels HD can generate. (Pixels are the equivalent of a horizontal scan line in analog.) While there are many different types of HD, the serial digital (RS292) version requires approximately 1.5 GB/s (750 MHz). By contrast, analog HDTV's bandwidth requirements range from approximately 93.3 MHz (per RGB channel) to 186 MHz (based on an SGI Onyx II generating a 1,600?1,024 image at a 76Hz frame rate).

NOTE 1. Some of the above figures came from Michael Robin's Broadcast Engineering article, Routing for Video. Michael is co-author of Digital Television Fundamentals, published by McGraw-Hill. Send questions and comments to michael_robin@intertec.com.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
Vertical Lines	1080	1080	1080	720	720	720	480	480	480	480	480	480	480	480	480	480	480	480
Pixels	1920	1920	1920	1280	1280	1280	704	704	704	704	704	704	704	704	640	640	640	640
Aspect Ratio	16:9	16:9	16:9	16:9	16:9	16:9	16:9	16:9	16:9	16:9	4:3	4:3	4:3	4:3	4:3	4:3	4:3	4:3
Picture Rate	60I	30P	24P	60P	30P	24P	60P	60I	30P	24P	60P	60I	30P	24P	60P	60I	30P	24P
Table 1. The 18 possible formats available in the ATSC system. Only the active viewable area is detailed. For example, traditional analog television consists of 525 vertical lines, 45 of which are not seen but used for vertical blanking, time code, frequency response tests and closed captioning (to name a few).

Format	Total lines Samples per line			Sample
frequency (Mhz) Frames per second
1080	1125	2200	74.25	30.00
720	750	1650	74.25	60.00
480 ? 704	525	858	13.5	59.94
Table 2. Sample Rates for the various combinations of lines, pixels and scan frequencies (frames per second). These values include timing, coding and ancillary information not normally seen.

NOTE 2. All of the above specs are for non-compressed, device-to-device transmission. For specific information, visit:

www.atsc.org The FCC's Advanced Television Systems Committee is in charge of broadcast standards. ATSC Documents A/53 and A/54 are free and informative.

www.smpte.org The Society of Motion Picture and Television Engineers' committees set the standards for digital cinema, as well as TV and motion pictures. Documents are accessible for a small fee.