Field workers of utility companies are regularly engaged in outdoor tasks such as network planning, maintenance and inspection of underground infrastructure. Redlining is the term used for manually annotating either printed paper maps or a 2D geographic information system on a notebook computer taken to the field. Either of these approaches requires finding the physical location to be annotated on the physical or digital map. In this paper, we describe a mobile Augmented Reality (AR) system capable of supporting virtual redlining, i. e., entering annotations directly with the AR device using simple point-and-shoot interaction. The AR visualization delivered by the system is constructed from data directly extracted from a GIS used in dayto-day production by utility companies. The models incorporate digital terrains and 3D representations of underground infrastructure, such as gas pipes or power lines. We also report on encouraging trials and interviews performed with professional field...