I Am Legend directed by Francis Lawrence

in the opening of I Am Legend we first hear non diagetic sound of a radio talk show, the sound with no pictures or images reflect that radio effect this links the idea of old fashioned and simple pleasured society in the ideology of the radio itself this gives the audience a sense of simplicity and reinforces that idea of going back in time which comes a clear idea carried on in the film. in the non diagetic voice over we also hear the word "New York" repeated this gives the audience a sense or location and something to picture as the film starts. Next we see a television news show talking about how they have finally cured cancer and as the scientist brakes the idea behind the cure down we hear her talk about "taking a natural thing and re-programing it" this links back to the idea of going back in time to simple society such as nature and how we rely on nature in this case as a cure but yet we destroy it in life today! to keep the film believable and real the director has chosen a big issue such as cancer to relate it to the audience and make the film a realistic outcome or event this is used in many other films of this genre such as "Eagle Eye" where it is based on the use of technology taking over and the Iraq war.
As the conversation about the cure end we hear a non diagetic musical crushendo this is another common feature to film in genre introducing a event or character in this case it is a drum scary sudden sound which instantly reflects somethings gone wrong or not gone to plan a complete contrast to what was said in the dialog, next we see long shots of empty major busy parts of new york such as a train station this being a long shot reinforces that something has gone wrong and really shows how there is literally no one around a shocking realistic shot creating that suspense and thriller tension backed up with ambient sound but not of a city of a jungle showing juxtaposition and linking the idea of nature and how it will always be dominate and survive,
next we cut to out main character our protagonist we can tell he is the hero because of the use of semiolidgy such as we see him driving a red mustang which dose connote danger but also reflects power and presence and we see with Will Smith a dog but not just any dog a police alsation dog all these signifyers symbolising a savour. As the dog sees something instantly the pace changes to a fast paced with using quick straight cuts, as the car chasing the deer around new york,this yet again goes back to the idea of nature as we see a car chasing its pray which is something usually seen on a nature programme where a loin is chasing prey not a car giving a contrast and looking at that idea of "re-programing nature" to finish and establish an action based thriller, iconic signifies are used such as the gun and the fast paced edit in between a slow paced edit to reinforce that action thriller convention.