Each tile includes five to seven related files containing the vector data listed above. DLG data are downloaded in a zipped GZ format and must be extracted by the user. Individual file names are long and confusing. Data files are best renamed as they are downloaded and unzipped. The SME paper available at the ESRI Web site will explain file downloading, extraction, and preferred file naming conventions.
File management is very important while downloading data.
The most difficult part of the entire 3D modeling process is downloading the DLG data from the Web, which requires time, patience, and organization. Converting data from DLG for use with ArcView GIS presents other issues. Translating data to an intermediate AutoCAD DXF format appears to be the most stable, intuitive procedure. The conversion can be performed interactively or in DOS batch mode. The CAD Reader for ArcView GIS will read the intermediate DXF directly including available elevation.