New microcomputer database system for maps

A microcomputer-aided drafting system is used at the Geological Survey of Canada, Calgary, to make large charts and legends for the Geologic Atlas of Canada. Hand-drafting of Atlas maps may be supplemented by a digital geologic map database created by a new microcomputer and videotracing system at CAL-CAD. Video-tracing is more rapid and discriminating than existing rasterscan and digitizing table systems, as an image of the map is multiplexed (overlain) on-screen with AutoCAD. Interactive tracing and storage of each data type as a separate layer of file aids accuracy, and adds great editing power and output flexibility to geological and geophysical maps, cross sections, logs, and other complex diagrams. New digital and old paper databases can be merged into powerful geographic information systems.