Las Vegas--As Rodney Dangerfield might say, they're a tough crowd. Spoiled by the best acts in show business, frazzled by hours at the gaming tables, visitors to Las Vegas want the finest entertainment that winnings can buy.

Yet, they are here, lining the Forum Shops at Caesars Palace, waiting to see an eight-minute show without a single human performer. Granted, they are skeptical: They wander through the rotunda, where the show is staged, studying the aquariums, the marble statues, the flowing fountains, and they scratch their heads.

But when the show starts, their doubts disappear. The statues drop from sight, replaced by animatronic figures that unexpectedly rise out of the fountain. Surrounded by a show of fire and steam, these performers argue with one another; they talk to the audience; they threaten, gesticulate, bend, turn. On closer examination, they seem almost human. Their eyes blink, their eyebrows move, their cheeks expand and contract when they speak. One figure leans wearily on his staff and slowly draws himself up from his chair. At the show's climax, the chair itself becomes an animatronic, transformed into a winged beast as the audience gasps in amazement.

"I stood next to people at the grand opening, and all I saw were jaws dropping,'' recalls Bob Crean, vice president of operations for Advanced Animations, Stockbridge, VT, the company that designed the figures.

Indeed, by the end of the show, many of the visitors also seem to have been transformed. As the show ends, even the most jaded in the audience find themselves applauding. There is, however, good reason for their applause: The "Atlantis'' show, which tells the story of the fall of the mythical lost continent, is a technical extravaganza. In addition to the animatronics, it employs stunning sound and video. Atop the dome of the rotunda, a giant god, whose face is at least two stories high, watches over the assembly and talks to the figures.

Behind the scenes, it's even more impressive. Miles of steel pipe and copper tubing supply the fire and steam for the show. Hydraulic cylinders to raise and lower the figures are as long as 35 feet. Custom-designed electronics and programmable logic controllers provide control for the lights, audio, fire, projection screens, and hydraulics.

For an eight-minute show, "Atlantis'' incorporates as much technology as any of the best rides at Disney or Universal. "We've rolled all the best special effects we could think of into a single show,'' notes Larry Lester of Lester Creative, Valencia, CA, creator of "Atlantis.''

Heavy lifting required. The show takes place in a classical rotunda, adjoining Caesars Palace's Forum Shops, which opened in late August. It tells the story of the struggle for power between Atlas' children, Alia and Gadrius, and the ultimate effect it has on Atlantis.

Lester, who managed the project for the Simon DeBartolo Group, was well qualified for the job, having previously served as vice president of show technical services for Universal Studios in Hollywood. There, he was responsible for Earthquake: The Big One, and King Kong, among others.

On "Atlantis,'' Lester's team decided to endow the show with the best special effects available, which is why, by some estimates, it cost between $15-$17 million. Part of that cost is in the show's setting: A fountain, waterfall, and giant 40,000-gallon, horseshoe-shaped salt water aquarium dominate the rotunda.

But the show itself, which runs once an hour, is what draws the crowds. It begins when the five "marble'' statues (they're really made of fiberglass) suddenly retract, and are replaced by the four animatronic characters. Much of the action takes place in the center of the horseshoe, where Atlas emerges from amid the fountain. At the same time, electric motors roll murals out of the way to make room for 18 large screens, which project images on the dome of the rotunda.

The show's animatronic figures are lifted into place by dedicated hydraulic cylinders. The figures, together with their hydraulic manifolds and turntables, weigh approximately 2,000 pounds each. Lifting these massive loads required 12-inch diameter cylinders operating at 1,500 psi. The telescoping cylinders, designed and built by The Marmac Co., Xenia, OH, have a 35'-4" stroke length. The 35-foot stroke is needed to lift the figures from the basement beneath the exhibit to an area high above it (see diagram). Because the cylinders are subjected to the fountain's water, The Marmac Company also applied a stainless steel coating to the cylinders to prevent corrosion.

To retract the statues, Lester uses a hydraulic cylinder-and-winch combination. The cylinder-and-winch enables one hydraulic cylinder to move two statues. By configuring the system in this way, he estimates that he saved as much as $200,000. The reason: He eliminated the need for two extra-long (35-foot stroke) actuators.

Lester also used hydraulic actuators to lift lighted crystals into the show area. In all, he says, he employed ten large hydraulic actuators to move the statues, animatronic figures, and crystals. Four 60 HP Vickers Integrated Motor Pumps supply the power for the hydraulic systems.

The design team never considered electrics for those tasks, for reasons of cost, complexity, and safety. "We're in a very wet area,'' Lester explains. "Electric motors for this application would need brakes and other extra equipment. Hydraulics is by far the best choice for a job like this.''

Complex control. Because the show employs so many different systems--animatronics, water, fire, hydraulic lifts--control is complex. For that reason, "Atlantis'' employs a master show controller that works in conjunction with other, specialized controllers for the animatronics and water effects.

The show's master controller, known as the Synthesis system, was designed and built by engineers at Triad Productions, Inc., Des Moines, IA. Synthesis employs two Hewlett-Packard Vectra PCs, intelligent card frames, an Allen-Bradley SLC-504 programmable logic controller, scanner, power supplies and operator interface. The system works in conjunction with a servo controller built by HR Textron/Micro-Precision, Berne, IN. The servo controller oversees all moves made by the animatronics. On a lower control level, dedicated Allen-Bradley SLC-504 PLCs oversee the hydraulic lifts, hydraulic pumps, and fire effects.

The main reason for the complex control system is that each physical move in the show must be carefully synchronized with both sound and video. Engineers orchestrate the control for the show by overlaying SMPTE (Society of Motion Picture and Television Engineers) time code onto each frame of the video. As a result, the video frames store information for every light, sound, and physical movement. It then synchronizes those moves so that the figures are in the right place at the right time. If, for example, a figure's arm is inappropriately extended as it is lowered off stage, it could strike the side of the work envelope and be damaged.

"These are very, very complex figures,''notes Bill Synhorst, vice president of Triad, as well as a software and hardware developer for Synthesis. "To be sure that the show works right, we have to know where the figures are at all times.'' That means that the system must store every move made by each character at intervals of 33 milliseconds, Synhorst says.

Realistic motion. Given the sheer number of possible moves for each character, such control becomes a formidable task. The character known as Gadrius, for example, has 45 separate moving parts. Engineers at Advanced Animations, Stockbridge, VT, designers of the figures, say that no character in the show is capable of less than 25 moves.

To make matters even more complex, these motions can be hydraulic or pneumatic, analog or digital. Gadrius makes nine distinct pneumatic moves, mostly in his face and fingers, some of required custom-designed cylinders. Gadrius' fingers, for example, use tiny pneumatic cylinders made by Fabco-Air, Gainesville, FL. The cylinders have a diameter and stroke length of just a half-inch. Other pneumatic cylinders for the figures are made by SMC Pneumatics, Indianapolis, IN.

The animatronics' larger muscle moves are actuated by hydraulics. Such motions as torso forebend and body sidebend employ hydraulic cylinders from OilDyne Division of Commercial Intertech, Minneapolis, MN. Rotary actuators from Parker Hannifin Corp., Cleveland, OH, are responsible for bicep rotations.

The quantity and quality of the moves is a key to the realism of the show, say engineers. Advanced Animations achieved that realism by designing so-called "hydraulic compliance'' into its systems. Hydraulic compliance is critical for animatronic figures because it enables them to manage the inertia caused by quick acceleration. In the past, that inertia was responsible for an animatronic phenomenon known as "boing.'' In "boing,'' a figure's movement stops suddenly, causing it to vibrate. In a typical scenario, a figure may bend from the waist, then shake furiously as it reaches the actuator's end-of-stroke. While "boing'' is more acceptable on a so-called "dark ride,'' in which low visibility hampers the view of the figures, engineers have worked hard for decades to find a cost effective way to eliminate the problem.

"Everybody in animatronics wants their figures to look human,'' says Bob Crean, vice president of operations for Advanced Animations. "But humans move fast, and it's sometimes difficult for animatronics to handle that kind of fast movement. The biggest challenge is to move fast, then quickly come to a dead stop.''

By incorporating hydraulic compliance, Advanced Animations engineers say they can solve the "boing'' problem. They accomplish it by employing dual-loop PID servo control. To provide force feedback, they place load cells from Entran Devices, Inc., Fairfield, NJ, between the cylinder's body and rod end. Force and position data are gathered in separate channels in a servo card. Using a proprietary combination of hardware and software in the servo card, the system processes force and position feedback signals, then responds with commands to dampen potential vibration.

In digital pneumatics, Advanced Animations uses a system called Advanced Inertial Management (AIM) to achieve compliance. Key to AIM is a small, custom-molded bumper made from Texin(R), a thermoplastic polyurethane made by Bayer Corp.'s Polymers Division, Pittsburgh, PA. By placing the Texin(R) bumper at each end of the stroke, engineers can program quicker robotic movements without the associated vibration, Crean says. "When a cylinder reaches the end of its stroke, it's going to bang,'' he says. "That's where you need compliance.''

Crean says that compliance can be costly and complex. For that reason, he says, it's best applied only to those situations where it's absolutely necessary.

On "Atlantis,'' Crean believes that the quantity and quality of the moves has taken animatronics to a new level. "We can safely say that these are the most sophisticated animatronics anywhere,'' he says.

The animatronics, together with the sound, video, and special effects, is thus far having the desired effect. "Atlantis" officially opened in August along with The Forum Shops, to an extravaganza that included blaring trumpets, indoor fireworks, and CNN coverage. "It's only an eight-minute show,'' he says. "But it's knocking the socks off the audiences.''