Watch the Water for Elephants trailer!

Water for Elephants, adapted from the acclaimed bestseller by Sara Gruen, is about the art of illusion. It's a Depression-era look at the rough-and-tumble yet romantic circus life, directed by Francis Lawrence (I Am Legend and Constantine), and starring Reese Witherspoon, Robert Pattinson and Christoph Waltz. And like the film itself, the vfx blend in seamlessly so we aren't aware of the illusion.

Crazy Horse Effects was the lead vendor responsible for 250 vital vfx shots, half of which involve a CG train and environments, plus a climactic stampede that craftily comps actual shots of animals rushing into the Big Top. Minor work was subcontracted to With a Twist Studio, Shade VFX and Skulley Effects.

Since most of the film was shot in Southern California with a principal train, with a quick stop in Chattanooga, Tennessee, to make use of a period train, that posed a vfx problem: there wasn't enough railroad track to travel with the train at night, and the Southern California environments had to be changed.

"So we basically had to turn California into upstate New York and provide the canopy, the trees, the foliage, for all of the train shots," explains Paul Graff, visual effects supervisor and president of Crazy Horse. "So the California train was all detailed out and the Tennessee train not as much. And then all the night traveling shots were day for night and done with visual effects, and all the big, wide shots of the train at night were mostly CG."

They also utilized a railroad museum in Chattanooga with private train tracks, but they only run through heavy foliage, so the open landscapes had to be blended with train tracks for backgrounds in order to create the epic-looking wide shots.

"The main challenge was to provide visual effects that do justice to the organic quality of the imagery and to not have something that sticks out," Graff continues.

"We wanted to let Rodrigo [Prieto] play, get his cinematography and give him a little extra and not create any conflicts. Every shot has so much passion. And there were a lot of dusk for night shots, and the challenge was to make them look as good and as real as everything else. There were full sky replacements, moving camera, and tracking every shot and putting interactive light back into place, mixing passes of a train coming at us during the day or during dusk hours and then coming in the middle of the night and getting those two train plates exactly matched. At the end, it worked out great but until you have it you don't know if you can pull it off."

Graff points to one early dusk for night sequence that was quite complicated in which Waltz and Pattinson jump from train car to train car. It begins with an Akela crane shot, they pull in for a close-up on the train and there are different backgrounds. "We have the set, and there's one environment shot in the Tennessee train track, and another environment shot on a country road and then we a CG environment and we have with CG train and CG smoke," Graff explains. "To marry all these things together from different sources, that all have to be tracked and stabilized and blended together, that was pretty difficult, I would say."