Most of these displays -- like the at Rockefeller Center in New York or the in Chicago -- are electrical extravaganzas, with basic white or colored lights blinking on and off.
But a few of these have enough computer power behind them to put even the Grinch-iest geek in a Christmas frame of mind.
Outside Disney's theme parks -- which are in a class by themselves when it comes to holiday spectacles -- one of the biggest and most sophisticated holiday light shows in the country is at in Pine Mountain, Ga.
Callaway Gardens' Fantasy in Lights show features 8 million sparkling lights, synchronized in time to music and narration along a seven-mile wooded drive. Behind the marching nutcrackers and swimming swans are computerized show controllers that use powerful networking protocols to turn lights on and off digitally and to operate analog light dimmers. Some of these cell-phone-sized controllers have the ability to use GPS technology to sync up light and music.
Visitors to Callaway Gardens ride on a "Jolly Trolley" or their own cars through a dozen lighted scenes, including Snowflake Valley, Magical Christmas Garden and Santa's Workshop. The show's highlights are electrical interpretations of two famous Christmas stories: 'Twas the Night Before Christmas and The Nativity. (See a of the Callaway Gardens Fantasy in Lights 2008 show.)
The Callaway Gardens' outdoor light show has been running strong for 17 years, attracting more than 150,000 visitors each holiday season.
Special-effects masterminds groomed by Disney make the Callaway Gardens Fantasy in Lights show work each year.
"We've been involved in the Callaway Gardens show from day one," says Bill Ferrell, who heads up , a special-effects systems integrator from Van Nuys, Calif. "We also do a lot of work for Disneyland, and this show really came out of a team of designers and producers who were ex-Disney people and were involved in the electrical parades."
Ferrell says what sets the Callaway Gardens Fantasy in Lights show apart from others around the country is the sophistication of the show controllers. Each of the show's dozen scenes has its own style of design and custom music.
"Santa's Workshop is the highest level of sophistication," Ferrell says. "We have background music tracks, but we also have sound effects built into the rhythm line. The sound effects are localized to different elements of the animation in the scene. If you look at the toy testing center, you have an elf pulling out a string to make a baby doll talk. You see that visually with the lights and at the same time the baby doll says 'Mama, Mama.' The words 'Mama, Mama' are in the rhythm line of the background music."
The lighted displays are on hand-sculpted wire frames with mini LED lights spaced one inch apart from each other. The animation effects are the result of these lights turning on and off in a precise time code, which is set to music. The music uses the standard MP3 digital audio encoding format.
"We have lots of relays and dimmer racks, but really the brains of the show are the little computers we use with digital playback features," Ferrell says.
Ferrell uses computerized show controllers from , a Burbank, Calif., company that is the lead provider of modular audio and animation "bricks" used by theme parks, parades and museums.
Callaway Gardens uses a Gilderfluke controller for each scene, which is housed in a 4-by-4-foot shed that includes amplifier racks, relays and dimmers. The Gilderfluke controllers use a specialized network protocol called DMX512, which is the standard in .
"DMX512 is a control protocol similar to Ethernet that is typically used in theatrical entertainment," Ferrell said. "If you're seeing a rock concert, and the lights change in color and pattern, all that is distributed through DMX512."
One benefit of DMX512 vs. Ethernet is that it carries traffic about a mile over a wired network without requiring a repeater. That's one reason most holiday light displays, including the one at Callaway Gardens, use wired rather than wireless networks.
Doug Mobley, founder and CEO of Gilderfluke, says his company's animation control systems and digital audio repeaters are Windows based but are more robust than off-the-shelf PCs.
"PCs don't run the shows because they're not reliable enough," Mobley says. "We have software called PC*Macs that is used for programming. It runs under Windows. It looks a lot like an audio or video editing program except that it's specially designed for animated light shows."
The PC*Macs software has a graphical user interface that allows users to program lights, music or fountains by simply dragging and dropping lines to control how quickly these features get turned on or off.
Gilderfluke's modular bricks start at US$100 each and can support as many as 512 dimmers each.
Gilderfluke systems are used at Disney and Universal Studios theme parks and underpin the Rose Bowl Parade.
"A whole parade can be networked off our little controllers, which fit in the palm of your hand," Mobley says. "That controller has a clock inside. It has a GPS plug-in if you need to be really, really accurate. It has audio playback off an Sd card, and it has the equivalent of a 500-watt amplifier. It's got a massive amount of power . . . to play back the show data that you've programmed into it."
Mobley says his company's controllers are ideal for lighting shows that operate faster than a human could control manually.
"We actually update the data at 30 frames per second," Mobley says. "We're sending out massive amounts of data so we can turn on and off every light on every frame. Even the most powerful lighting board would lock up."
Ferrell estimates that the entire Calloway Gardens Fantasy in Lights show has around $6 million worth of lighting, sound and computerized controls.
"The IT component would be around $750,000," Ferrell says, adding that his company earns $850,000 a year supporting Callaway Gardens.
Ferrell says the Callaway Gardens holiday light show is "definitely the most sophisticated in the country. It's the difference between the major leagues and the minor leagues."
"As far as I know, Callaway Gardens is the most sophisticated holiday light show in the United States, certainly as far as the controls are concerned," Mobley says. "It's a question of how the lights are synchronized with the sound."
For other high-tech holiday light shows, check out these YouTube videos of displays at , , , , and