ABSTRACT
The commercial success of Windows 95 made it possible to write graphics software that would run on a
large proportion of personal computers. In early 1997, the U.S. Geological Survey (USGS) wrote two
Windows 95/NT programs for displaying USGS cartographic data sets. The dlgv32 program displayed
digital line graph (DLG) data as colored lines with attributes, and the dem3d program displayed digital
elevation model (DEM) data as perspective terrain models. Later versions of dlgv32 display a variety of
other data formats. Between June 1997 and August 1999, about 78,000 copies of the two programs were
distributed over the Internet. They continue to be downloaded at around 100 copies per day.
The primary purpose of the software is to allow easy and cheap previews of USGS products. The viewers
contain no analysis or editing functions and therefore do not compete with commercial geographic
information system (GIS) products. Despite these limited capabilities, the viewers fill a need for some
USGS customers. Many potential users of GIS data are unfamiliar with the field, own no GIS software, and
appreciate free software to help them visualize digital cartographic data. The experience suggests that
limited government development of freeware may be appropriate in support of earth science data programs.