Abstract
High-speed filming of collisions of vehicles with e.g. obstacles can be used to yield quantitative information. To get the deceleration history of the vehicle the series of positions read from the film should be different tinted twice. As the positions are corrupted with noise, the differentiating should be done carefully in order to get a reliable signal. The paper deals with how this can be arranged and gives the properties of the method. One important parameter of the problem is the standard deviation of the error in the positions. A rule of thumb, employable for quantative filming in general, is presented to estimate this parameter.