The Battle of Helm's Deep is not only the largest action scene in The Two Towers, it's one of the biggest battles in the entire trilogy. So what's Peter Jackson secret weapon on this huge filmmaking feat? The miniatures department. Alex Funke, Visual Effects Director Of Photography for The Lord of the Rings' miniatures unit, talks about his team's formidable tasks and sizable achievements in creating Helm's Deep.

I joined The Lord of the Rings before live-action production started to help set up the miniatures unit, which we created from scratch.

We found an empty building and made it airtight, and we built all the motion-control equipment, including four huge boom rigs, because there wasn't any in New Zealand.

Early on, we began to call our work "bigatures," because even though we're dealing with miniatures, sometimes these things become enormous. Helm's Deep is a good example of that.

It required three different sets, two of which we built on the Helm's Deep location, at a quarry outside Wellington, because we needed the room.

The first set was what we call full-size partial builds, pieces of ramparts and walkways that are big enough for actors to actually perform on, and with room for real ladders, real fire, and so forth.

Then there was a quarter-scale set, which we used just for overall shots of the fortress. Because this set was exposed to the elements, we couldn't really do fine detailing, since it would fall off as soon as it rained.

For real detail work, we created an indoor 1/35th scale set, which is the one we used for all the "helicopter" shots of the battle scenes down on the foreground, and for the shots flying above the tower, because those wouldn't work in the quarter-scale model.

Once the set was finished, we would block a shot and Peter would approve the camera location. Then we'd do a hyper-detail of exactly what the camera's going to see.

That's where we use higher grades of dust or better quality weeds and so on. Because getting the weeds the right size or getting the trample marks where the troops have marched through is what makes you believe it's a real shot.

One of the main segments in the Helm's Deep siege is something Peter wanted, where Orcs get a ladder up to the wall and the defenders push it back and it falls over. It sounds simple, except the ladder would've been 100 feet tall in the real world, and they could never shoot that.

So it had to be done partly miniature and partly digital. We used the 1/35th scale set, starting with a little camera move looking out over the parapet and the defenders. There are archers firing arrows, people throwing spears, and we see the ladder come up over the parapet.

As the Orcs are ready to climb over, the defenders start pushing the ladder with big poles until it reaches the vertical point and crashes on the ground. So the miniature is the set, and then digital fills in characters up on the wall and Massive Orcs down below.

In effect, we're trying to simulate a live-action shot at a small scale, which means we have to make camera moves that look like action moves. To do this, we have to move the camera very close to the set.

That's where the motion-control camera comes in. This is a motor-driven system with a tracking computer that allows you to do the same camera move exactly the same way until you've got the shot you need.

The other piece of this puzzle is a snorkel lens, which is just a long periscope, like a submarine periscope, except with a camera lens on the end of it.

We use this because we often have to shoot really close to the model, and the camera won't fit. It represents an actor's eye-level point of view, for example.

I first read this book in 1961 and I've read it probably a couple of times every year since. I never thought anybody would actually make a film of it.

Fortunately Peter said, this is not about effects, this is about telling a very beloved, very moving story. If we see the effects, then we did the job wrong. Peter is completely dedicated to making films that are convincing.