DLG (Digital Line Graph)

Digital line graphs are digital vector representations of cartographic information. They are drawn from aerial photos, or other cartographic information. Thet can be represented in either large scale, medium scale, or small scale.

Image Source: http://www.humanitarianinfo.org/imtoolbox/03_Mapping_GIS_GPS/GIS/GIS_Reference/GIS_General/GIS%20Poster_files/figure1a.jpg