Some quick ILM factoids:
HULK (2003) arguably one of their best efforts:
- 6 months to render 36000 frames.
- Avg. frame render time: 4 to 13 hours (depending on the complexity of the shot)
- Hulk model had 100 layers of skin, 1165 muscle shapes
- It took 200 ILM employees and 2.5 million computer hours 1.5 years to produce
Star Wars Ep 3 (2005)
- 170,000 frames
- 750-1500 computers
- 49 seconds of the Mustafar duel took 26 shots, 1185 frames, 910 artists a total of 70,441 hours to render.
Poseidon (2006)
- Opening sequence was 4000 frames (3 minutes of movie time)
- 1 hour for pre-pass, 4-5 hours per frame (7-8 for night shots)
- 5 to 6 days of non stop rendering
- 300 computers used
Hulk in 2003 took up to 13 hours to render some complex shots. Double the CGI models and complexity and I can easy see it being 24 or so hours.. add in pre-pass time and yeah, it sounds about right.
Yes, the 38 hour quote came from Bay in the Empire interview, but no one seems to be contesting it. I wouldn't doubt it given the complexity of the project. He's probably counting pre-pass and design work in that 38 hours.