From my discussions with Shaun we though of how to represent the information in a more visual way. I liked the idea that the bluetooth only suggests that a person is there but gives no real location or form to them. I looked for a number of examples of photography that shows blurred almost ghost like figures. I particually liked this:

This picture is taken using a camera with a very low shutter speed. They way these anonymous people form a cloud. Using the data to create this kind of effect could be a good way to visualise the information collected.