Film poster for Brother. Photo provided to chinadaily.com.cn

For the actors in the upcoming wartime thriller Brothers, the biggest challenge was to perform against a green screen, imagining it was, in fact, a battlefield.

The movie, set in World War II, features brothers who are tragically turned into rivals as they fight for the Communist Party and Kuomintang armies.

While most war-themed movies shoot battle scenes by constructing fields and then bombing them, the film shun the big-budget methods by using cutting-edge technology.

Up to 1,800 action scenes, depicting fierce gun battles and bombings, were all shot indoors and then finished in post-produced with high-tech computer programs, according to the movie's director, Liu Xiaoguang.