The virtual Erwin was also swapped for the real Erwin just as the huge gator chomped and began to thrash him about.

This effect was accomplished by first filming the scene with the actor, Darrell, entering and taunting the gator. At this point, there was nothing there except a marker on the ground to signify where the gator would be.

Next, the same scene was shot without Darrell (the camera tripod was anchored with sandbags so it would not move between shots).

In post production, the two shots had to be combined so that Darrell would vanish within a frame. This way the virtual Erwin could assume his place. Sound easy? Not really. Conventional wisdom would say to edit the empty scene in following the last frame in which Darrell was supposed to be in.

This would work fine if the scene was shot indoors or in a sound stage where all elements were controlled. Doing this here would cause an obvious jump-cut because the moss in the trees and the grass were moving from wind, not to mention that the lighting was constantly changing as clouds passed over the sun. The time between scenes was more than enough for the lighting to change dramatically.

Instead, we rolled the entire footage containing Darrell on an upper layer and punched a hole through the scene where he stood with a garbage matte when he was to disappear. The empty scene was run on the lower layer to fill the matte with the identical foliage. This way the change in motion and lighting would not be nearly as obvious as overtaking the entire scene.

Next, this footage was imported into Lightwave as the background composite and was projected on a 3D ground plane so the gator and virtual Erwin would cast ground shadows on the video footage.

The virtual gator was added and animated. As he lunged for Erwin (the frame where Darrell vanishes), the virtual Erwin was placed in the scene and his first pose was matched to the last frame of Darrell's pose. From there the gator and Erwin were animated to appear that the reptile was thrashing Erwin from side to side like a side of hog.

In the final stages, the texture, bumps, transparency maps were added to both the gator and Erwin and a motion blur filter was applied. The final step was to make the gator apear to be lying in the grass on the video footage. This was done by using the Sasquach plugin by Worely. This plugin, which creates 3D hair and fur on 3D objects, helped us to grow tall grass sparsely from the ground plane giving the illusion the gator is buried in the grass.

This same effect was used to make the gator appear to stand up and charge Erwin. This too was the virtual Erwin placed close to the virtual camera and applying a depth of field filter to dither him out of focus.