The visual effects work in "Twister" required the creation of various tornadoes that would interact with (and tear up) the ground, buildings, trees, cars, tankers, cows, tractors, farm equipment and other debris. Initially, it was my responsibility to execute a test for director Jan De Bont to show that it was possible to create the tornadoes. We wanted to give him full freedom on size, motion and structure. We chose to use particle simulation on the computer to create the tornado. This resolved the issue of fully
integrating the many separate passes of debris and objects into the dust, allowing for seamless compositing and camera matching of the tornado.
Since this was a whole new territory, we created a 400 frame test showing a driver's POV of an F5 tornado shredding a barn as a tractor falls out of the sky, sending a tire into the windshield. Whether we could create a believable effect with the right amount of detail for film was unknown. Even if this were possible, how would we light the particles to shadow themselves like clouds do? And would the number of particles needed fit in the computers? Would the process be fast enough for us to deliver on time? The test was successful and the movie was green-lighted. The last 2 seconds of the shot were used in the "Twister" trailers. Once the project began, my role was to work with the software group to develop the particle renderer and implement the larger tornadoes, devise a technique to shred structures and train and supervise a group of 30 effects animators to execute the shots.

Stefen Fangmeier (USA) joined the Computer graphics department at Industrial Light & Magic in 1990. His first major project was "Terminator 2: Judgement Day". Since then he has worked as a Computer graphics Supervisor on "Hook" and "Jurassic Park", the digital character co-supervisor on "Casper" and visual effects Supervisor on "Twister". Fangmeier received his degree in Computer Science from California State University of Dominguez Hills in 1983.