Novelists are not equipped to make a movie in my opinion. They make their own movie when they write: they're casting they're dressing the scene they're working out where the energy of the scene is coming from and they're also relying tremendously on the creative imagination of the reader.
Sometimes a character is really based on research that you do. Other times it's just based on your imagination or perhaps your conversation with the director. Or sometimes all of the above. It depends on the movie and character.
