Issue 154 of the official Star Wars newsletter has a short article about the creation of Mustafar in Star Wars Episode III Revenge of the Sith. VFX Supervisor Roger Guyett and Model Supervisor Brian Gernand discuss how miniatures was combined with digital effects and footage to create it.
Here it is:
Mustafar has become one of the most spectacular sites in the galaxy. A world of jagged obsidian cut through by searing rivers of lava, the hellish landscape became the perfect setting for the tragic finale of Revenge of the Sith. It's not a world of comforts, and neither was bringing it to life at Industrial Light & Magic.
"We used a series of fairly large miniatures to create the immediate landscape," explains Visual Effects Supervisor Roger Guyett. "Outside of that, we used digital technology, using textures from the models themselves to extend them out. Then even further, we used a lot of moving 3-D matte paintings and HD footage of actual volcanoes. It's really an elaborate tapestry of pieces."
The heat blasted facility perched atop a blackened cliff face was a digital model, but the rocky landscape and much of the lava flow was captured practically. "We ended up with a 30-by-40-foot set of the seemingly uninhabitable topography of Mustafar," says Brian Gernand, Practical Model Supervisor. "It was a rock-like environment with a four-foot wide and approximately 40-foot long path of lava coming down. Included with that were tributaries, waterfalls, all kinds of other inlets and glowing hot spots around this environment."
To give the viscous lava the illusion of self-illuminating heat, the 15,000 gallons of Methylcel needed to be penetrated by a light source. The bottom of the river beds were actually transparent, with powerful lights shining through the thick goop. "I think, in the end, there was a calculation of something like 250,000 watts of light under the set that were being blasted through," says Gernand. "That's what made the stage environment such a difficult place to be -- it was about 110 degrees on that stage!"
Guyett concurs that the stage conditions for the Mustafarian lava flow miniature was hardly heavenly. "It's one of my favorite moments from working on Star Wars," he says. "The guys start shooting the model and they're all in shorts, there's smoke on the set... It's like actually working on a volcanic planet. I would just turn up for 10 minutes and say, 'Things look beautiful here.' (But) I would think, "... I'm glad I'm not doing this all day long!"