Definition: Heads-up digitizing
UN - Geographic Information Systems
A digitizing technique that does not employ a digitizing table. Instead, features are traced with a mouse on-screen either from a scanned image displayed in the background or following features drawn on a clear medium (e.g., mylar) that is attached to the computer screen.
United Nations, "Handbook on Geospatial Infrastructure in Support of Census Activities", Department of Economic and Social Affairs, Statistics Division, Studies in Methods, Series F No. 103, New York, 2009