Ferran Domenech, animation supervisor from The Moving Picture Company did a talk at Animex about how they went creating the visual effects and animation for Prometheus. A key thing that was brought up was to always test the rigs before you go ahead with the animation, every control needs to be tested as you need to be sure everything is in working order before proceeding. Going ahead with a faulty rig would end up wasting time, effort and money as it would have to be fixed and the animation re-done. In order for the animation to line up they matchmoved it allowing the animation to be in the correct position in correlation to live action footage and 3d models. We never got to use this technique so it was interesting to see the different breakdowns they took to achieve the final result. Along with matchmoving the footage, they also made sure the alien pressed up against the glass of the helmet in one shot. This would add to the believability and realism of the shot and make the viewer visually see the alien inside the helmet. All the small details count, so adding smears on the glass from the slime will add to the overall final appearance.
The environment composed of different layers being composited together, the ground plate actually came from Iceland yet the cliffs came from another country. These were all shot on location with the actors and then the cg models/animation along with the visual effects were put in afterwards. For a film like this the viewer knows it's not real, however they still need to be immersed within the film and while they are watching it they should feel part of it. To sustain this immersion a big part of this is to make sure all the cg components are seamlessly integrated with the live action footage. Neither should look out of place, both should look and feel like they come from the same thing.
MPC Prometheus VFX breakdown! from MPC on Vimeo.