Emerging requirements for digital maps for in-vehicle pathfinding and other traveller assistance

As Advanced Traveller Information Systems (ATIS) technology matures, new in-vehicle applications are arising: pathfinding, business listings ("Yellow Pages"), cartographically attractive displays, integration with Global Positioning System (GPS) technology, and communications with real-time traffic information services. Each of these impose new demands on digital maps supporting ATIS. We present examples of each and describe the nature of supporting map data. For pathfinding the following data are used: a topological database, driving restrictions, including complex multi-link turn restrictions, and street classifications used in computing impedance. More advanced and attractive graphics displays, e.g., color LCD and CRT screens, permit color fill for such areas as water bodies and parks. As a result, purely cartographic information, useful primarily for making the map display more attractive and recognizable, may become a significant portion of the map data. GPS is now widely available, and many manufacturers are including GPS receivers in their designs and prototypes. This requires, in most cases, a change in coordinate systems, for example in the US from NAD27 to WGS84. Finally, identifying particular links for communication with real-time traffic information services imposes requirements for cooperation among developers. Operating examples of these new requirements in use are presented together with a brief review of earlier requirements, including positional accuracy, street classification and geocoding support. These are needed for display, map matching navigation, as well as new applications, such as business listings searches.