1. A method for facilitating detection of a presence or an absence of at least one underground facility within a dig area, wherein at least a portion of the dig area may be excavated or disturbed during excavation activities, the method comprising: A) electronically receiving, at a first user location remote from the dig area, source data representing at least one input image of a geographic area including the dig area; B) processing the source data so as to display at least a portion of the at least one input image on a display device at the first user location remote from the dig area; C) in advance of the excavation activities and at the first user location remote from the dig area, sketching environmental landmarks or virtual white lines, via a user input device and a drawing application associated with the display device, on the displayed at least one input image to precisely identify boundaries of the dig area, so as to generate a marked-up digital image including the environmental landmarks or the virtual white lines to delimit the dig area; and D) electronically transmitting and/or electronically storing information relating to the marked-up digital image so as to facilitate the detection of the presence or the absence of the at least one underground facility within the dig area.