"While the baby Kaiju scene was typical special effects, the big battles were 100% CG. The action was on such a huge scale. There aren't any boulevards in Hong Kong wide enough for that type of action. There is quite a lot of destruction and water interaction in the movie that we had to incorporate."
Keeping the human element
Being computer generated didn't mean that a human element was lost, though. In fact in creating the movie the practical nature of the creatures harked back to Japan's Godzilla movies of old, where the term Kaiju was coined and many of the monsters were portrayed by men in suits.
"We had a lot of conversations about the 'man in suit' look for the movie. That's what was so great about those Kaiju films. When, say, Godzilla got hit by a rock there is this sort of suit shake – the guy inside the suit actually shakes the suit! It is signature to these movies.
"What we did with our creature effects was pay homage without going all the way."
As for the 250-foot Jaegers, focusing on the smaller details of the suits helped the movie, reckons Hickel, even though Pacific Rim was all about monster bashing on an epic scale.
"It was tough figuring out the physics for the Jaegers. We didn't write tools to exactly replicate what a robot that size would do as it would feel too big, too ponderous, heavy, huge and boring. Some of the size came from editing and clever shot design and camera shots," says Hickel.
"Instead we felt it was important to differentiate the Jaegers. They are are so slow, so we paid attention to pieces that could move without arresting the motion. If you did that stop-start thing it would feel goofy.
"We focused on the smaller incidental details and put little mechanical accents on smaller areas of the Jaeger to help with the scale."
Attention to 3D
On the big screen, 3D helped these little details pop out and Pacific Rim is one of the few movies where this technology works well, despite being an afterthought for the movie. Hickel puts this down to taking time with the conversion.
"Good 3D is all down to attention. As we were rolling into the 3D, John Knoll had already been involved with Star Wars conversion. He knew it was possible to do it well but you have to spend time on it. Fortunately, when it was announced that the movie would be 3D Guillermo became engaged with 3D. Straight away he sought John's eye for the movie.
"The big concern for us was miniaturisation. You shoot these 250-foot tall characters and bad 3D would make them look flat and small. Fortunately del Toro was concerned about this as well and kept an eye on it."
After battling miniaturisation, it's obvious that size does matter for Pacific Rim – which makes the movie's arrival on Blu-ray an interesting one. Will it retain its epic feel on a smaller screen, especially for those who saw the movie on IMAX?
Hickel doesn't think it will be a problem, though he does admit that even though he worked heavily on the movie, he didn't see it on the biggest screen possible.
"I never actually watched Pacific Rim on IMAX, but I am really curious about it in the home. It may not have the same feel but it will definitely be enjoyable," explains Hickel.
"We are in an age where many people are having such big screens in their home and I am dying to see it on Blu-ray.
"It is probably not a good film to watch on your iPhone, though."
Pacific Rim arrives on Blu-ray 3D, Blu-ray and DVD on November 11 from Warner Bros and Legendary Pictures. Own if first on digital download from November 4.