The authenticity of a documentary is ‘deeply linked to notions of realism and the idea that documentary images are linked to notions of realism and the idea that documentary images bear evidence of events that actually happened, by virtue of the indexical relationship between image and reality’
Horness Roe. A. (2013) Animated Documentary. Basingstoke: Palgrave Macmillan.
The main function of documentary is to restore what happened in reality to the film and television, usually using the video or pictures recorded at that time to prove its authenticity. So documentaries are realistic.