The biggest issue, according to Farhat, was trying to match flat photography to conversions and have it intercut with native. Typically, with native, you have action coming forward and the picture playing into the seats, whereas with conversion your depth is from the screen backwards; and so in order to blend it seamlessly they had to generate a lot of 3-D elements and fly them in the comp forward in the picture plate. That's why you see a lot of arrows flying forward along with debris and blood and guts and bullets.

Gretel battles a witch. Sequence photo credit: Hammerhead VFX / Paramount Pictures.

 

 

While the troll was done mostly animatronically, there was a lot of CG face replacement by Hammerhead to get the expressions right and also when he briefly talked. "But we also had a completely CG Edward when he busts out of the 3-D forest line and runs forward and grabs a tree and leaves and debris," Farhat explains. "He's particularly effective during an over the shoulder scene with Gretel, where they changed his whole face in there.

"But one of the problems is that the character's eight feet tall, so the arm pits of actor Derek Mears were more than a foot below the real arm pits, so the troll could never really raise his arms over his head. And when he needed to lift his arms, we were attaching CG things." Hammerhead did the modeling in Maya and used Nuke for all the compositing.

"The other thing is a lot of exteriors were shot on set so we added a tremendous amount of plates and generated skies so that we had volumetric clouds. There were a lot of pieces and we had witches flying on brooms and the casting was such that except for Zoe Bell, who's a fantastic stunt woman, who played the more aggressive witches, we used a lot of local actors. They struggled to sit on a broom, much less fly and flip around on the thing, so putting them on wires and flying them around set was not doable. So we put them on broom rigs and we just had to fly the set past them, so we shot a lot of cable cam of backgrounds flying through the forest, and since Tommy's style was to put the camera with the witch, it was like looking at the car next to you on the freeway. You're just seeing the backgrounds moving."

Framestore created the cg Candy House complete with dripping frosting.

 

As for the witch transition scenes, they turned her into the ugly witch with a combination of CG and makeup. But what's interesting is that the CG Candy House was done late in the schedule by Framestore. There was a Candy House set built, but it proved logistically unsuitable. "By the time we shot, we essentially roto'd the kids out and created an entire CG Candy House with dripping frosting and real volume type of transparent candy, and then, of course, generating that for both the left and right eye. That was pretty aggressive and one of the things when it's all said and done you go, 'That was a nice set they built.'"

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Bill Desowitz is former senior editor of AWN and VFXWorld, the owner of Immersed in Movies (www.billdesowitz.com), a columnist for Thompson on Hollywood at Indiewire and author of James Bond Unmasked (www.jamesbondunmasked.com), which chronicles the 50-year evolution of 007 on screen, featuring interviews with all six actors.