Methods and apparatus for facilitating detection of a presence or an absence of at least one underground facility within a dig area. A digital image that does not include an aerial image of a geographic area including the dig area is displayed on a display device. Via a user input device associated with...http://www.google.fr/patents/US20090237408?utm_source=gb-gplus-shareBrevet US20090237408 - VIRTUAL WHITE LINES FOR DELIMITING PLANNED EXCAVATION SITES
VIRTUAL WHITE LINES FOR DELIMITING PLANNED EXCAVATION SITES
