1. A method of distributing map data from a map server to a wireless communications device, the method comprising: obtaining vector map data in response to a request for map data received at the map server from the wireless communications device; generating a bitmap array that is a low-resolution representation of the vector map data for a particular location specified in the request; computing attributes of the bitmap array to determine which map features are to be retained and which map features are to be omitted; simplifying the map data by omitting at least one map feature to thereby provide simplified map data; and transmitting to the wireless communications device only the simplified map data for the map features to be retained.