See a shifting, flashing formation of lights in the sky? Is it a bird? Is it a plane? No, it is a drone show. And they are all the rage.

These performances involve multiple drones putting on a choreographed show, often with flashing lights and set against music.

And the largest in South-east Asia - a 300-drone performance - is set to brighten Singapore's skies this Wednesday during the National Day Parade (NDP).

Expect formations such as an outline of the Singapore island, the Merlion and this year's NDP logo to adorn the night sky.

This new type of aerial entertainment is taking off in Singapore.

At least seven other drone shows have taken place here - typically lasting from three to eight minutes - based on the battery life of the flying vehicles.

The earliest drone show here - which reportedly was more of an indoor drone display - is believed to have taken place at the Singapore Airshow at Changi Exhibition Centre in 2014, involving 12 drones.

This was followed by several six-minute performances by 16 light-bearing drones at Gardens by the Bay last year, as part of the exhibition titled The Future Of Us, which provided a glimpse of daily living in the year 2030. That drone show depicted national icons such as the Singapore Flyer.

In May this year, an eight-drone performance took place in a Shangri-La Hotel Singapore ballroom, as part of the entertainment during this year's Singapore Tourism Awards, organised by the Singapore Tourism Board (STB).

Before 460 attendees, the four- minute show featured drones seemingly interacting with two live dancers - floating up when the dancers glided beneath them and surrounding and circling the performers at one point.

A month later, 50 drones lit up the skies in front of the Marina Bay Promontory for the DBS Marina Regatta's finale.

For three minutes, the drones formed shapes such as a glittering spiral and a flashing "DBS" sign rotating in the sky, and danced to a specially commissioned piece of music by Singaporean composer and music producer Eric Wong.

Event organisers say they are drawn to the fresh concept of drone shows and have received encouraging feedback about them.

Mr Oliver Chong, 49, STB's executive director of communications and marketing capability, recalls: "The audience was delighted by the innovative and cutting-edge drone performance. It was a photo-worthy moment with many attendees using their devices to capture the moment with photos and videos."

Mr Wan Wee Pin, 43, deputy director of The Future Of Us exhibition, says: "The show was very well- received and word-of-mouth after the first show meant an increase in the number of audience members for the subsequent performances."

An Internet search shows that there are at least three companies that organise drone shows here.

One of them, home-grown company Infinium Robotics, has put on four drone shows in Singapore as well as other drone shows in Japan, China and Malaysia.

Its sales manager Arjun Pootheri Edakkat, 28, says drone shows have a wow factor, an association with innovation, and allow clients to showcase words, shapes and various choreography in the sky, which is not usually possible with fireworks.

"Drone shows are also environment-friendly as the drones do not emit smoke and pollution."

Intel, the company behind the drone light shows at the DBS Marina Regatta and this year's NDP, has a fleet of drones designed specifically for putting on entertainment light shows.

Called the Intel Shooting Star drones, each GPS-equipped flying vehicle can create more than four billion colour combinations.

The company has technology that can automate the creation of an image and quickly calculate the number of drones needed, determining where they should be placed, and formulate the fastest path to create the image in the sky.

Ms Natalie Cheung, Intel's general manager for drone light shows, says there are many considerations in a drone show. For example, organisers have to work with local aviation regulatory bodies on permits and exemptions, and ensure a safe show.

Occasionally, problems can occur.

For example, at the NDP Preview 1 on July 22, the drone show could not proceed due to an unexpected loss of GPS signal in the performance area.

But the performance was successfully conducted during the NDP Preview 2 on July 29, as well as at two other rehearsals.

Ms Cheung says: "There are many variables to executing a successful drone light show. Unfortunately, certain environmental conditions including GPS signals, which are crucial to drone flights, are beyond our control."

According to the Civil Aviation Authority of Singapore website, operator and activity permits are required for the flying of drones for any business purpose. Such purposes are understood to include the performance of an aerial drone show.

However, no permits are required if the drones are flown indoors in private residences, according to the website.

If permits are required, applicants are encouraged to apply for them well in advance of the show. The expected processing time for an application is two weeks.