The trailer for AVP-R shows off the CG spacecrafts in action that bring the battle to Earth. TM & © 2007 20th Century Fox. All rights reserved.

Film sets can be combative places, with department heads butting heads over any number of disputes. But in the case of Aliens vs. Predator: Requiem (opening Christmas Day from Twentieth Century Fox) -- the second film to pit the popular sci-fi franchises against each other -- directors Colin and Greg Strause couldn't help but be on same page as their visual effects supervisors because they were the visual effects supervisors.

Colin Strause, who, along with brother Greg, heads up the vfx house Hydraulx, says having no such boundaries on their first feature-film-directing gig was a liberating experience. "I would literally go from the edit bay and then sit down on a Maya machine and start building shaders for the movie," says Colin. "So I still love doing both."

Colin Strause says he and his brother used to make Super 8 movies when they were children. Their desire to be a part of the movies was kick started by Terminator 2, which Colin says inspired them to move out to Los Angeles and break into showbiz. "For directing, it was kind of like, 'Yeah, it's going to be cool,' but it was a pie in the sky kind of dream," Colin admits.

After failing to land their dream jobs at ILM, the Strauses started doing vfx work on The X-Files in 1995. They jumped into features in 1996 and have since founded Hydraulx and worked on more than 40 films, including The Nutty Professor, Volcano, Titanic, The Day After Tomorrow, Poseidon and 300.

The duo began directing music videos in 2000, followed in 2001 with commercials and a pair of sponsored short films, Mute and 16mm Mystery. But Colin says it was the good will he and his brother had built with Fox, in particular, that landed them the job.

"We've a had a really good relationship with Fox, to the point where in meetings the co-chair of the studio would talk about Hydraulx as being the company they would want to do certain sequences. It gave us good awareness with all the same people that we'd have to be dealing with as directors," he adds.

Colin says they made an unsuccessful pitch for the first Alien vs. Predator film, then pitched a movie called Wolfenstein that Fox almost bought. "When the script came up for this movie, they though we'd be perfect for it because it's an ambitious movie for the budget that they had and they knew that having our visual effects background was going to be a huge thing," Colin offers.

The brothers' vfx experience allowed them to shoot the film and execute the work in the most efficient way possible. "One of the biggest issues with movies right now that we see as an effects company is the amount of money that isn't as efficiently spent as it could be," Colin suggests. "There are people who use motion control when they shouldn't, so instead of getting 20 setups a day they only get three and then they don't even use the mo-co data."

Hired on in late spring of 2006, the brothers had limited prep time before shooting began in the fall. "We didn't have a lot of time to sit around go. 'I don't know, what do you think of this?" Colin says. "It was like fucking war every day, but it was the funnest thing we've ever done."