A lot of the film's designs went through multiple stages of development — vehicle designer Paul Ozzimo recalls that lead vehicle designer TyRuben Ellingson handed him early designs that were roughed out in a program called Sketchup, and looked like Legos rather than finished designs. It took a lot of fleshing out to build those into full 3-D models.
Bartoli recalls that seeing his creature designs come to life "as Weta started animating and lighting them" was a bizarre feeling. For one thing, now his Hammerhead and other creatures were part of a whole world, where they belonged as part of the ecosystem. Says Bartoli:
It's a very strange thing to design a creature, then see it begin to live and breathe in other people's hands... Seeing the first passes at the lit shots of the Hammerhead standing in the Helicoradian Glade was a milestone for me — here was the creature I had designed smashing up trees in the forest location I had painted. We had crossed over into the world.
Adds creature designer Tully Summers,
The design process with Jim was very deliberate and methodical. He always had an "end" target in his head even if he didn't know the specifics, almost like trying to recall details of a favorite but vaguely remembered dream. We did sketches, clay maquettes, and paintings. Ultimately digital sculpting proved to be Jim's favorite tool for evaluating the creatures. Allowing him to see designs he would be shooting in 3D from all angles in real-time was invaluable.
Every single sequence had to be composed, from color to backdrop, to get the maximum effect. Recalls Messing:
The love scene between Jake and Neytiri was something that Cameron wanted to be bold so we used vibrant purples and violets. I did several paintings designing how the trees would frame the intimate moment. I kept the color saturated and intense; using the emanating glow of the willow tree to silhouette the lovers' embrace. Cameron spent a lot of time choreographing the performances to get the scene just right. In the end he decided to utilize a shallow depth of field to simplify the composition and create a more iconic image.
Throughought the process, there was a lot of on-the-fly innovation going on. "We were building an airplane in flight," says Stromberg.