Advances in the low-power embedded space complement those in high-performance computer-graphics animation, such as the innovations shown in the latest "TRON LEGACY" movie.

Disney’s original science-fiction classic, “TRON,” is credited with ushering in the age of computer-graphics (CG) animation. Today, CD animation quality is so life-like that viewers have trouble distinguishing live-action elements like real people from their CG-generated counterparts – e.g. as in the “Avatar.” In the recent sequel to “TRON,” called “TRON LEGACY,” CG animation was used to create a very convincing younger version of the now-older protagonist, Kevin Flynn (played by Jeff Bridges).

The advances in CG filmmaking reflect the marvels of 30 years of advances in high performance semiconductor PC-server hardware and computer programming technology. What have gone unnoticed have been equal advances made in the world of embedded electronic systems. Let’s look at just one aspect of the improvements brought by the embedded and sensor technology revolution: illumination control.

Virtual Light

By today’s standards, the original “TRON” movie had very little in the way of computer effects. At the time, it was state-of-the-art. Yet many of the computer-generated scenes looked little better than the graphic-limited video games of the day. The suits in “TRON” weren’t illuminated. The “TRON look” was achieved by shooting the movie normally in black and white and then enlarging every frame to 8-x-10, black-and-white film positive cells for rotoscoping. This technique allowed animators to trace over live-action film movement, frame by frame, for use in animated films.

“For ‘TRON LEGACY,’ the suits actually illuminated on their own,” explains Alan McFarland, CTO for Nila - specialists in film and television lighting. “Motion-picture cameras have more than enough sensitivity to capture the illumination as is, making digital rotoscoping of the suits in post-production mostly unnecessary.”

Most suits also contained a detachable Identity Disc or Light Disc that was a key element of the story. The disc was usually mounted on the user’s upper back.

Inverting Power

Light-emitting diodes (LED)-based light discs and self-illuminating suits need power and control - even in the virtual world of “TRON.” This is where the use of tiny, low-power embedded systems can win out over the more costly expense of post-production CG animation.

To achieve the flexibility needed by the actors, the suits in “TRON LEGACY” were illuminated with custom electroluminescent (EL) material that could be shaped into various patterns. McFarland points out that some of the suits, such as Sam Flynn’s costume and Clu’s outfit, had more than 50 individual pieces of EL material. That material totaled some 1100 square inches per costume–-almost half of the entire area of a typical human body.

The EL material required 290 V AC at 1100 Hz—albeit at very low current. This unusual power requirement necessitated the creation of a custom 150-W inverter to convert the direct current (DC) from the battery pack into alternating current (AC). Sam’s costume required two of these inverters while Kevin Flynn’s costume—with fewer but much larger pieces of electroluminescent material—required four inverters.

These inverters were usually located in the Identity Disc hub, which was mounted to the back of the suit (see Figure 2). The available space inside the disc hub was about the same volume as a softball. Each disc contained at least two 150-W EL inverters plus a daughtercard for the wireless-network lighting control and monitoring module. Power for this embedded system was supplied by batteries that were typically located on the waist of the actor and disguised to look like part of the costume.

The new, super-high-energy-density batteries were developed especially for the Tesla Roadster. On the Sam Flynn and Clu costumes, these batteries provided about 11 min. of runtime. They could be fully recharged in 15 min.

The limited disc space meant that all of the electronic components had to be as small as possible. Unfortunately, smaller inverters generate more heat, which limited the maximum runtime of a single movie take to about 8 min. before the suit would overheat, notes McFarland. “Usually, this wasn’t a problem, as Joe Kosinski—the director—set up shots that ran considerably shorter.”

Wireless Embedded Hollywood

An integral part of the embedded system used in “TRON LEGACY” was the wireless-network lighting control and monitoring module, which was developed by Synapse Wireless Inc. By using the company’s “SNAP” network, Nila’s McFarland was able to turn the suit lighting on and off instantly. Furthermore, the SNAP wireless software returned data to the control computer screen, showing battery levels, runtime, and inverter temperature. This real-time data enabled the movie’s director to maximize the use of special effects by monitoring the suit battery life and inverter temperature.

An appropriately phrased “Sleepy Mesh” state in the SNAP network was used to awaken the radio frequency (RF) transceivers on the nodes as needed. “Sleepy Mesh” didn’t merely put one node to sleep but could issue a network-wide sleep scenario. (Think of the first encounter with the Borg on Star Trek.) The power savings from having the entire network sleeping was significant.

Each Synapse system contained eight (8) ADC inputs, 10 to 20 digital-output interface control ports, and a low-power, 2.4-GHz, IEEE 802.15.4 personal-area-network (PAN) RF module. (see Figure 4). “You can even get the SNAP software on a microcontroller the size of a fingernail to embed into clothing,” explained Wade Patterson, CEO of Synapse.

Testament to the ease-of-use feature of the modules is that the code to control the suit lighting was developed in less than two weeks, according to Patterson. The coding was relatively easy, thanks to a Python virtual environment that separates the application development from the underlying network-protocol details. (The combination of SNAP and Python is referred to as SNAPpy.) “End-user wireless applications are compiled into processor-independent ’byte code‘that is run on the virtual machine. This means that the same application can be run on any processor without the need for recompilation,” explained Patterson.

Virtual machines running on wirelessly connected embedded processors? Doesn’t that sound vaguely like the world of cyberspace in “TRON?” Perhaps the writers of “TRON LEGACY” should’ve included at least one snappily attired program element in the movie to acknowledge the advances in the real world of embedded systems.

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