Pixel Magic's main work involved the Indian sweat hut, where scarred, vengeful Hex (Josh Brolin) is revived through mystical powers after being beaten, branded and left for dead by Turnbull (John Malkovich).
Inhaling and exhaling smoke is one thing, but then the smoke turns into the image of a crow and then a real crow crawls out of his mouth and flies off like an image from a horror film.
According to Ray McIntyre Jr., Pixel Magic's visual effects supervisor, director Jimmy Hayward  wanted to first confuse us before revealing the power of the Indian lore, as demonstrated by the crow.
McIntyre suggests. "The smoke was done with 3ds Max  and Fume FX by Rif Dagher [the CG supervisor]. He created those shots where he's both inhaling and exhaling.
"The smoke crows were done by Rif as well. We animated flying crows and then had them emit smoke. It was a request that it be somewhat mysterious because they didn't want the audience to get it until later on and then realize that it is a precursor of the crow later falling out of his mouth. So it had to be more of a soft, nebulous shape at first that took the form of the bird. It took us some time to get the look that the director wanted to see. It was kind of unique in the sense that it was not something we've done a lot of."
The crows were also a challenge as well. Pixel Magic has done birds before, including crows, but not like this. Usually they're moving with lots of motion blur. But the requirements of this sequence were quite different.
"Here was a sequence where there was virtually no motion blur because the crow's coming out of his mouth," McIntyre continues. "That put more pressure on what the crow had to look like and the comping of the feathers. Also, when he crawls out of the mouth, you actually see the bird open his wings. And your rig is much different for a bird that has to start with his wings tucked in and then opens them up. You don't want to have to worry about issues of interpenetration of your model and geometry and things like that. It's somewhat difficult to pull off because obviously you know it can't be real: a crow can't grow out of a human's mouth, so it immediately puts you in a state where you know it's computer-generated. But it amps up the need for reality even more to get it to a point where you can believe that it's a real crow coming out of that mouth."
The crows were a combination of Maya  and some custom tools for the feathers. Beau Cameron did the close up work; Edwin Braun did the wide shots.
Another challenge was that there were reshoots ordered after test screenings late last year. Initially, Ariel Velasco-Shaw  was the overall visual effects supervisor on set in New Orleans, with McIntyre overseeing the 2nd unit vfx at night. But when the climax was deemed too tame, and an explosive attack on Washington by ship was added, Hydraulx was enlisted to handle the vfx. Originally, Turnbull's terrorist plot was foiled by Hex and the Navy before the boat could leave the dock.
However, Pixel Magic would resume work on the sweat hut, among other things. "We actually started the sequence last July," McIntyre recalls. "We delivered one shot, it sat for a while and we continued to work on it this year."
The other big shot for Pixel Magic occurred in a roundabout way. There's an exploding boat on the river toward the end. However, when the attack on the capital was later added, Pixel Magic returned to the shot with a new flourish.
"It was actually our last shot that we delivered and it was given to us after first being cut from the movie," McIntyre explains. "All of a sudden, two weeks before delivery, they decided to put it back in but no longer as a static dry dock shot of the boat exploding from overhead, but where it's now cruising down the river. We rotoscoped the boat out and put in the CG water and the fire balls and the cannon barrel blowing off. And the explosions were made by Riff along with the live-action elements composited in. We composited everything in After Effects: Brad Moylan was our compositing supervisor. It was a big rush for us at that point. It was a lot of effort because of the time crunch."
Bill Desowitz is senior editor of AWN & VFXWorld.