1. A method of displaying areal features which is represented by polygon fill of vector data for world maps and other display items by signal transformations of data representative of areal features from which polygons are extracted comprising the steps of: feeding said data representative of areal features from which polygons are extractable to a computer; establishing from said data representative of areal features in said computer, display geographic coordinate relationships for display and interrogation; transforming said data representative of areal features in said computer, into a great circle polygon format for display; selecting from said data representative of areal features in said computer, background and overlay features for display; determining from said data representative of areal features in said computer, spatial relationships between spherical polygons for display; processing said data representative of areal features in said computer, to provide clipping and singularity removal at map interruption lines to allow the display of curved surface features in a plane; clipping polygons from said data representative of areal features in said computer, by lines so that portions thereof are dipslayable as separate entities; projecting from said data representative of areal features in said computer, geographic coordinates onto a defined map display; providing transformations from display coordinates to latitude and longitude coordinates for the display thereof, said transformations being derived from said data representative of areal features in said computer; and displaying a representation based on said data representative of areal features in said computer.