When film-maker Kirsten Tan met the elephant Bong, she was smitten.

"It's like the Brad Pitt of elephants. It's the epitome of an elephant," she says admiringly.

In fact, she thought it too perfect a specimen to cast in her movie Pop Aye, which is about a Thai architect who chances upon his long-lost elephant and embarks with the animal on a journey in search of the farm they grew up on.

"It was too majestic-looking, too good-looking. I wanted something more real and raw," she says.

Popeye, in the film - the movie title is an off-kilter take on the name - is a street elephant, so she was looking for a creature that was sadder-looking and past its prime.

But in the end, Bong and its "generosity of spirit" kept drawing back Tan, who wrote the script after a scene she had witnessed, of a group of boys pulling an elephant out to sea to bathe, stayed with her.

It was the first pachyderm she met on her research trip in early 2015 to a small town in Thailand's Surin province. The creatures have been a part of life there for many centuries and it is where a lot of elephant handlers and experts are from.

She stayed with a family of mahouts for about two weeks as it was important to her to ground her film in reality.

"I didn't want to make (it into) some cartoon, cute, Disney elephant," she says.

Ultimately, it took the 35-year- old three years to write, research, cast and shoot the movie, which had a budget of just under $1 million. Filming took place last March and April in mountainous Loei in north-east Thailand as well as in Bangkok.

Pop Aye will premiere at the prestigious Sundance Film Festival, which starts on Jan 19. It is the first time a Singapore movie will compete at the largest indie film festival in the United States, says its production company, Giraffe Pictures. The film is up for several awards, including the World Cinema Grand Jury Prize, World Cinema Directing Award and Audience Prize.

Previous Singaporean directors at Sundance include Royston Tan, with youth gang drama 15 in 2004, and Meng Ong's Miss Wonton, about a Chinese immigrant in New York City, in 2000.

Looking back, Kirsten Tan says Pop Aye was a "very, very, very tough shoot, beyond what I expected". Even her Thai veteran indie-film producer Soros Sukhum - whose credits include Aditya Assarat's award-winning romance drama Wonderful Town (2007) - concedes that it was his most challenging project.

Having an elephant in a film sounds like a "cool, magical concept", but the execution of it was anything but straightforward.

The number of permits required to film an elephant on the street was daunting, and transporting it within Bangkok was challenging as well - one could travel with the animal in a truck only within a specific window of time each day.

And while 21-year-old Bong is smart, it is still an elephant, which means "it slowed down the process by so much", Tan says. After one take, it would have to be repositioned before it slowly ambled back to the starting point.

She adds: "We went in thinking, 'Oh, it's a road film, we want to keep it small, keep it flexible.' But in the end, everything had to be extremely planned for safety reasons."

Accordingly, the crew size swelled to as many as 100 a day. There were five elephant handlers on set, including one to feed the star and one to scoop up its poop.

To top it all off, it was the hottest summer in Thailand in four decades when they filmed. Bong had to be hosed down constantly and Tan would put ice in her safari hat to keep cool.

The experience notwithstanding, Thailand was a country that seduced her when she was in her 20s.

"Singapore was extremely controlled, almost a little authoritarian. It was the diametrical opposite, it was a place which was full of chaos, grit and dirt, and it felt like there were no rules. It was pretty liberating and it felt very attractive," she says.

After completing her advanced diploma in film production at Ngee Ann Polytechnic in 2005, she chalked up film festival accolades for her short works, such as 10 Minutes Later (2006), about causality, and Fonzi (2007), about a character who realises she is not real.

She has since collected more than 10 international awards and is a four-time Silver Screen Award Nominee at the Singapore International Film Festival, where she won Best Southeast Asian Short Film for Dahdi (2014), in which an elderly widow living on Pulau Ubin comes across an asylum-seeking girl.

Around 2008, Tan dove headlong into Thailand for about 11/2 years. There, she helped run a market stall, formed a rock band and visited film sets.

She later graduated with a master's in film production at the Tisch School of the Arts, New York University, in September 2014, and has lived in New York for close to a decade.

The energy and hopefulness in the Big Apple buoy her, but she feels that could end up being a cosy bubble absent of practical concerns. So she comes back here once in a while to get that bubble pricked as she gets bombarded with pragmatic questions about her next pay cheque.

While she calls Singapore her anchor, the place she is most comfortable in, "there are also times when I feel like I don't really belong here either".

For the moment, she sees herself continuing to shuttle between the two places.

Her peripatetic journey lends a degree of intrigue to her identity as a film-maker as people try to figure out her style. Plus, her taste in films is "super wide", ranging from the works of arthouse auteur Tsai Mingliang to popcorn movies such as the Jurassic Park dinosaur thrillers.

She herself would accept the tag of "accessible arthouse", in the vein of, say, local film-maker Anthony Chen's family drama Ilo Ilo (2013) and the works of Spain's Pedro Almodovar and South Korea's Park Chan Wook, "stuff the audience can follow and enjoy, but there's still an artistic element to the film".

Just do not call making movies her passion. To her, that suggests an ardour that might cool off, whereas it is, in fact, her "purpose, a career, a life".

"It's all of that to me."