Mielants — who has previously directed two seasons of Legion, the first TV series connected to the X-Men film series — said he had no problems encouraging his cast to strip off, including NZ acting royalty Clement.
He added that as the movie was based on real-life experiences, avoiding nudity in some scenes would take away from the story he was trying to tell.
And the cast quickly got used to their state of undress in some scenes.
"I think all the actors felt it wasn't about the nudity," he said.
"It was trying to tell another story. Actually, we all considered it a costume drama. Costume dramas are actually never interesting because of the costumes."
Since becoming a global comedy sensation with Bret McKenzie in the Flight of the Conchords TV series between 2007-09, Clement has also appeared in a raft of hit movies; including lending his voice to several animated hits.
His film resume includes Rio, Rio 2, Men in Black 3, Muppets Most Wanted, The BFG, Moana, The Lego Batman Movie and Dinner for Schmucks.
He is also set to play Dr Ian Gavin in the second and third installments of the Avatar movie series.