Forensic animation is the use of full-motion computer graphics to recreate an event such as an automobile accident, the collapse of a building, an assault, or the workings of a mechanical device from a variety of perspectives. Forensic experts, police officers, engineers, and eyewitnesses compile the data and supply it to the animators, who create a series of fixed video images that are assembled to create a cartoon-movie-like rendition of the event. Simulated audio is sometimes also used to create a short audio-visual production.
A typical sequence in forensic animation consists of 30 frames per second, and lasts for several seconds. Scenes are generated using various computer programs working in combination. The event is typically depicted from two or more vantage points. For example, a collision between a small car and a truck might portray the moments before, during, and after the collision as seen by the driver of the car and by the driver of the truck, and also as it would appear from several external locations. Each video can be recorded on analog tape so it can be played on a common videocassette machine for multiple viewers. Alternatively, the final production can be burned onto a digital video disc ( DVD ) and presented using a computer with a projection display.
The accuracy of forensic animation depends on the precision and verifiability of the data used to create it. In a car/truck accident, for example, it is important to know prior-to-impact data including the speeds of the two vehicles, the precise directions in which they were traveling, the masses of each vehicle, the points on each vehicle at which contact was first made, and whether or not (and to what extent) either vehicle was accelerating or decelerating. This data might be gathered by testimony of one or both drivers, eyewitnesses, police officers who came to the scene after the accident, and engineers who analyzed the structural damage to the vehicles and the skid marks (if any) left on the roadway. The nature and condition of the pavement, the weather, the condition of each vehicle's tires, and the reaction times of the drivers would provide important additional data. Some vehicles have on-board computers that store important information about the operation of a vehicle at various points in time. Even a slight change in one of the parameters can result in a drastic change in the outcome. Often, several different scenarios are generated based on substantially the same testimony.
Forensic animation is gaining increased acceptance in courtrooms nationwide. Realism can enhanced by the use of three-dimensional ( 3-D ) programs such as Fizt or Maya . Some attorneys are experimenting with the use of virtual reality in courtroom litigation.