The Harpies, meanwhile, are in two sequences, including the climax where they chase Perseus riding on Pegasus through the streets of Argos on his way to battling the Kraken. MPC handled the Harpies, Pegasus, Argos and the Kraken. "We had a lot of interaction and had to deal with the Pegasus at that point," Davis adds. "Sam was on various rigs and we had stuntmen that we did head replacements on. Obviously every time we saw the real horse, we had to track the CG wings onto it. It was quite a challenge tracking something on that's moving and all black. MPC tracked the wings onto every shot and also did the fully CG Pegasus whenever it was flying."

The Kraken, of course, was a tremendous five-month undertaking, not the least of which was trying to avoid what ILM had achieved with the mythological squid monster in Pirates of the Caribbean: Dead Man's Chest.

"Once we got the design down, then it was a matter of figuring out how this 500-foot creature would look and behave," Davis suggests. "How could we have it wallowing in a bay and not look so stupid that we'll never work again? We wanted tentacles, but didn't completely want to anthropomorphize it and have a bloke wandering through, so we wanted to have the feeling that it was from the depths of the sea. That was something MPC worked very hard on, developing their water pipelines and software using FlowLine and creating multiple splashes and water simulations that enabled us to get the feeling of thousands of gallons being flicked through the air and the impact of it colliding with other water surfaces and the creature constantly pouring out of every crest like a moving water fall. And that took a lot of development and render time. We had this 45-second shot of the Kraken rising up out of the Bay of Argos and they used about 260 water simulation passes on that to create the different caches that would make up this enormous volume of water cascading off the different parts of the creature, but it got shortened in the movie. And, of course, every time it impacts another surface that required a different FlowLine system to make those collisions work."

For the ancient city of Argos, MPC created all of the geometry for the various buildings using photographic textures from India, Morocco and Europe for photorealistic grounding.

"For this city, which is built on 2,000-foot cliffs, we went to this place called Los Gigantes in Tenerife, and we took thousands of digital stills of the cliffs and they became the basic diorama through which the city was found," Davis adds. "And we built it at different resolutions knowing that certain areas had to be a lot more detailed than others."