Mak Remissa was 7 years old when he embarked with his family on the grueling exodus from Phnom Penh to Kampot province, a day after the Khmer Rouge took control of the capital in early 1975, and ordered its citizens out.
They walked for five or six days, he said, camping on the roadside at night.
“They just said go, go, go,” Mr. Remissa said of the soldiers herding the procession. “When we walked, walked, walked, very tired and just rested a little bit, the Khmer Rouge said, go, go, go.”
April 17 marks 40 years since the Khmer Rouge captured Phnom Penh. Mr. Remissa depicts the ensuing eviction of the capital in “Left 3 Days,” a series of 15 photographs.
The title refers to what the cadres told residents at the time: leave for three days. Most who left thought they would return. Many did not.
Mr. Remissa’s images are among those exhibited in Photo Phnom Penh 2015, which opens today and concludes on February 28. The festival showcases works by 20 photographers at 12 venues across the city.
Created in 2008 and curated by renowned artistic director Christian Caujolle, this year’s festival features established photographers such as Mr. Remissa and Kim Hak, as well as rising talents like Neak Sophal and Khun Vannak, alongside foreign photographers including Dutch artist Ruud van Empel and France’s Charlie Jouvet.
While Mr. Caujolle said he didn’t select particular themes, two arose: memorializing the past under the Khmer Rouge regime, and questioning the future of urban transformation.
For his commemoration of Khmer Rouge history, Mr. Remissa retrieves details from memories that struck him most viscerally as a young child—of an abandoned Phnom Penh, and the long walk to his father’s village in Kampot province.
He recalled, for example, seeing silhouetted figures of armed Khmer Rouge soldiers patrolling the streets of the city during the evening of the takeover.
“That night, Phnom Penh was very quiet,” he said. “We were so scared. If they found us, they will kill [us].”
The family left the next day—his parents, three siblings and grandparents, and three uncles, each with his own family—taking the road south.
“I saw some things strange like I had never seen before,” recalls Mr. Remissa, referring to men carrying the elderly in hammocks, the sick lugging their IV bags and endless crowds carrying on their heads what few possessions they could salvage.
And then, he added, “I saw the bodies, soldiers, dead on both sides of the road.”
Mr. Remissa employs an unorthodox method to reconstruct these memories. He uses paper to represent people, the flat figures about the size of a hand. With the help of assistants, he arranges them using gravel to simulate the road. Then, smoke.
“At that time, the soldiers were fighting so they bombed everywhere and smoke [was] everywhere,” Mr. Remissa explains. “Smoke everywhere, so hard to see.”
The wisps—from charred coconut skin—form soft, voluptuous lines, both eerie and exquisite.
Waiting for the smoke to achieve the right effect, however, means that each image can take days to complete.
But the resulting haze gives the images their haunting quality, reminiscent of dark memories slowly resurfacing.
Meanwhile, Mr. Hak’s series, “Alive,” takes a different approach to visualizing Khmer Rouge history, by creating poetic portraits of small objects that people held dear as they suffered through the brutal period.
Like Mr. Remissa, Mr. Hak thinks it imperative to impart these memories.
“It’s a dark history but we need to know, we need to learn from it, we need to pass the knowledge, the experience from generation to generation,” the 33-year-old artist said.
“That’s why I titled it ‘Alive,’ so the memory should be alive.”
Alongside these profound reflections on the past, other artists in the festival are concerned with the future.
Singaporean photographer Caleb Ming and Thailand’s Lek Kiatsirikajorn aim their lenses at urban transformation.
Mr. Ming has worked on “Plot,” a series on green spaces dotting the built-up city of Singapore, since 2012.
“They are not parks although they do look like parks,” Mr. Ming said in an email.
“These land[s] are set aside for development and they could stay vacant from months to years. Since development in Singapore is always happening, these plots are being used up,” he said. “It suddenly struck me that we will be losing these plots and all that space we still have.”
Mr. Ming associates the loss of such green spaces with the destructive prioritization of economic growth at the expense of human connection.
“I do not know how Singapore will turn out in time but I sure hope that we will become a more people-centric society rather than one that is run like a company,” he said.
Further north, Mr. Kiatsirikajorn grapples with urban change in Bangkok.
His images depict the city’s migrant workers in peculiar spaces, where resolute vegetation grows in stark contrast with concrete.
“At the beginning of this project, I only wanted to photograph the landscapes to portray the contrast between nature and the modern development of Bangkok,” the artist said in a statement. “My interest was shifted when I met rural migrant workers in these spaces, and started talking to them.”
“To me agriculture is the taproot of Thailand. Nearly half of the population are farmers. Our tradition and culture are directly related to it,” Mr. Kiatsirikajorn said.
Yet the workers leaving that tradition seeking a better life in the city instead find themselves trapped between their rural heritage and an out-of-reach urban future.
Space and time—and how people interact with them—are also at the heart of French photographer Corinne Vionnet’s series, “Photo Opportunities.”
Ms. Vionnet, who began the series in 2005, layered images taken by tourists of iconic sites: among them, Paris’ Eiffel Tower, Berlin’s Brandenburg Gate and, of course, Angkor Wat.
She was inspired by her own trip to the tower of Pisa in Italy, where she reflected on the similar vantage points in typical tourist photographs.
“‘Photo Opportunities’ tries to speak about our collective memory and the influence of image through films, advertisements, postcards, the Internet, etc.,” she explains via email.
“It raises questions about our motivations to make a photograph and our touristic experience. It visualizes our image consumption and how ubiquitous images actually are.”
Each image is a personal memory, but once merged, Ms. Vionnet says, they become shared memories.
To help spark conversation on such reflections, Photo Phnom Penh 2015 will also host several discussions with photographers, including a roundtable on history and memory with Mr. Remissa, Mr. Hak and Mr. Jouvet, who is behind “Words After Phnom Penh,” digitally retouched photographs that present images of an empty Phnom Penh, as if the events of 1975 were to recur in the city.
In addition, the festival will also showcase works by graduates of the Institut Francais’ Studio Images, a photography workshop led by Sovan Philong, which will recommence in February and runs until November.
This year, we see the 2013 Angkor Photo Festival Best Photo Story winner Ms. Sophal’s curious portraits of homeless workers in “Hang On,” and Mr. Vannak’s debut series of self-portraits entitled “Numbers.”