Search form

'Prey Alone': Not Your Typical Irish Short

Andy Stout looks at the impressive greenscreen and other CG work that went into the 15-minute short from Stephen St. Leger and James Mather. Includes QuickTime movie clips!


Prey Alones creators freely admit that their short is a home movie done by geeks, but they were able to pull it off with style. All images © 2004 Fantastic Films.

If you have the QuickTime plug-in, you can view clips from Prey Alone showing the greenscreen work and a trailer for the film by simply clicking the image.

There are many good things about the rise of CG in the cinema, but probably one of the least highlighted and potentially most powerful is the increasing democratization of filmmaking as an art. Yes, its still expensive and, yes, its still difficult, but CG is not only enabling filmmakers at the top end of the scale to realize their visions on screen, its also helping those with humbler budgets tell stories that would just have been simply beyond them before.

Prey Alone, a 15-minute short and a futuristic, dystopian film straight out of the thriller mold, is a case in point. The directors, Stephen St. Leger and James Mather, had the desire to create a film featuring two elements, a car chase and an interrogation scene. And so they did just that, throwing in some thrills such as an exploding fighter plane along the way.

Once upon a time, of course, it would have cost a ridiculous, John Landis amount of money to put that amount of car chase on the screen. But, by shooting in 16mm against greenscreen and, apart from a few hand props, creating the backgrounds and objects entirely in 3D, St. Leger and Mather were able to pull it off with style.

Two things remain highly unusual about it, however. First, its an Irish film, but an extremely atypical one. Not your typical Irish short film! comments its website ( succinctly. In fact, it doesnt even have a priest as one of the main or supporting characters. No panoramic vistas, no poverty, misery or guilt and its not even set in the 1950s.

Secondly, the comping and tracking on all 350 effects shots was done at home on domestic computers and rendered out at 2K resolution. As St. Leger freely admits, Basically, its a home movie done by the geeks.

Genesis and Creation

Any description of the plot would ruin its impact on first viewing, so well leave that alone. Suffice it to say, therefore, that beyond the desire for car chases and interrogation, St. Leger and Mather also profess a liking for the works of what Mather refers to as cinematic parlor games as exemplified by the likes of David Fincher (Fight Club) and M. Night Shyamalan (The Sixth Sense, The Village, etc.). Mather, meanwhile, had been kicking specific car chase ideas and concepts around for a while (I was always doing tests of one form or another in 3D its how I relaxed on a weeknight) before they finally decided to name a date to get a script delivered and began to focus on the film.

The planning of the shoot itself from a technical standpoint was actually kind of vague, he says. Sets had been roughed out in 3D and we knew how we were going to light them, where the actors would be standing and the general feel, but we didnt storyboard all the scenes. The interrogation, for instance, was just two guys talking, so we left much of that up to the day in terms of shots. In a funny way, we restricted ourselves too much in terms of camera moves and freedom with the camera and actors. In hindsight, some of the most successful stuff was the handheld stuff, when one character punches another for example. The freedom of the camera helps the digital backgrounds sit in so much better.

Those backgrounds were created by a small CG team consisting of Mather, lead 3D animator and compositor Jonathan Ridge, senior CG artist Eddie Sheanon and CG artists John OConnell, Robert DArcy and Paul Flanagan. The main software used was 3ds max for all the 3D work and After Effects for pretty much everything else.


Once upon a time, it would have cost a ridiculous, John Landis amount of money to put a car chase on screen. Mather and St. Legers expertise in greenscreen helped them achieve their goal cheaply.

3ds max is a great package, admits Mather. We used version 5, an older version than the current release, and the out of the box scanline renderer. The great thing was that Jonathan was a SOFTIMAGE|XSI man and had never used max, but owing to its user friendliness, by the end of day one was animating final shots. Also, After Effects saved our lives. Its a great package and very easy to use and learn. It also provided many `render hacks, which we used to bypass computationally thorny depth-of-field renders and so on. It really is amazing how much stuff you can achieve in it.

Some models were brought in. The Harrier, for example is a retextured off the shelf model from De Espona Infographica, while the car driven by the antihero was also taken from a 3D model collection. All sets were built by Mather himself.

As ever, tracking is crucial when it comes to greenscreen work. Most of the tracks were achieved in 2D using a combination of After Effects and rendered stills, which were then animated using flares and some subtle effects to give the impression of movement. Three-dimensional tracking was kept to a minimum.

The three-dimensional tracks we did, we were very careful about, adds Mather, making sure not to see the feet and so on as we couldnt guarantee a lack of slide. You can get away with quite a lot then and just massage it in AE. By the end, we were completing about 35 shots a week rendering, tracking, animating, comping all at 2K res. Which, when youre working on a Pentium 1.2mhz (which I was), is not bad going.


The trailer shows off Mather and St. Legers work. The film was shot in 16mm against greenscreen with mostly 3D backgrounds and objects. The comping and tracking were done at home on domestic computers and rendered out at 2K resolution.

Filming Against Green

Both Mather and St Leger work in the commercials industry and have used greenscreen techniques extensively in the past. Mather admits that actors can sometimes find themselves all at sea with the technique, but balances that against the fact that you get through a lot of camera setups in a day.

One of the strange upsides to greenscreen is that you can now take shots out of context and use them in different ways, suggests Mather. For example, when the car escapes the hotel, there is a shot of an actor standing in the control room listening to the police radios. In the edit, we wanted a new angle on him because the situation has just escalated so we took a shot from elsewhere in the film and dropped in the appropriate background and added a camera move in on him and suddenly, from nothing, created a new shot that previously hadnt existed.

The downside is that you hand a lot of control for the final look and lighting over to the 3D artists, which in this case was fine because I was one of the 3D artists! Being honest, I suppose, you essentially push the problems from the shoot onto post-production.


Mather, St. Leger and crew slaved through 18-hour days, seven days a week to produce this short. Their nine PC renderfarm took up Mathers study, but heated the house nicely.

Home Rendering

Though completely unprepared for what Mather describes as the complete horror of the final post schedule and pulling 18-hour days, seven days a week, the production went through fairly smoothly.

We had a nine PC renderfarm set up in a study in my house and then John OConnell set up the render connections, explains Mather. They were twin 2.8 GHZ towers wired to a central hub which used backburner to render. A pretty standard system, but not only were they very space inefficient but also they heated the house! We lost a couple on the way through owing to general overheating but they performed pretty well.

After leaving Mathers house for the final time, Prey Alone was finally conformed on Windmill Lanes high-def flame in Dublin before being sent to The Mill in London for the high-def film transfer. Since then? Well, Mather and St. Leger would be the first to admit that Prey Alone has so far failed to set the film festival circuit alight. Its difficult to work out why, to be honest, though. It looks absolutely stunning, has a very claustrophobic and paranoid feel that dovetails well into the current media landscape, and its got a neat, compact storyline. In fact, its a very high quality 15 minutes. Maybe if theyd had a priest in it and set it in the `50s

Undaunted, however, the pair are hard at work on their next project, a feature film screenplay titled The Shadowkeeper. What will they do differently when it comes to producing that?

Next time, an office, muses Mather. And a 100 PC rack system renderfarm with air conditioning. But apart from that not much.

Andy Stout is a U.K.-based freelance journalist who has spent more than a decade writing about 3D and vfx for numerous magazines in the U.K. and elsewhere.