Embodiments of the invention involve providing assistance data to a global position and navigation receiver, for example topographical data, such that the receiver can decide on a specific action depending on that data. The topographical data may include one or both of geographical data and architectural data. Geographical data may include information about natural formations, such as hills, valleys, forests, etc. Architectural data may include manmade formations, such as streets, buildings, bridges, etc. The receiver may then interpret and decide on a course of action for controlling the receiver base on the assistance data.