Symbolism in the opening.

There is some use of symbolism in the opening scene. The barbed wire symbolises entrapment and harsh authority, like in a Military facility. Also, the ripped up "EVACUATION" banner is used to expose some backstory, implying that something has happened many years ago, which caused people to leave whole areas behind. Lastly, there is a shot which pans right across a tall gate, overgrown with a padlock in it. The sun is in the centre of the padlock, symbolising a lack of light (metaphorically) in the world.