 One of the most important assignments of the unit was to develop navigational and topographic materials to support the bombing campaign against Japan . This top secret series of films , code @-@ named " Special Film Project 152 " was , according to Gregory Orr , " perhaps the most important and challenging effort to come from the First Motion Picture Unit . " The unit was given forty days to produce the films which would be used by B @-@ 29 Superfortress crews . 
