Converting downloaded GIS data

Updated June 2004

You may need to unzip or untar the files you download. Most files available for download are stored in a compressed format so that they take up less space on the server and download faster.You should be able to decompress them using one of the readily available tools such as PkZip or Winzip. To make things easier, turn off the Save Folder Information (or whatever it's called in your software) option.

If the file is in ArcInfo exchange or Interchange format, e00, you will need to use the Import71 utility or ArcToolbox->.Import to Coverage->Import from Interchange. This will convert the files into a format readable by your GIS software. The main difference (for your purposes) between ArcInfo format and Shapefile format is that ArcInfo uses an extra folder called Info to store information about the coverages.

All Arc Coverages at a certain hierarchical level in the directory (or folder) structure put administrative files in the Info folder. This means that you can't just copy a coverage from one place to another using the Explorer! You can move them with ArcCatalog (8.x) or Manage Data Sources (3.x)

DEM (Digital Elevation Model) coverages need to be imported with the Spatial Analyst extension. Once this extension is loaded, the Import Data Source option will appear on the File menu. For Oregon GIS Service center DEMs, choose the USGS DEM type from the Import File type dialog box. To merge multiple DEMs (mosaic) you will need another Script, such as ggmosaic.ave, freely available from ESRI.COM, under ArcScripts.

DEM data can be imported in 8.x using the ArcToolBox->Import to Raster->DEM to Grid

Other data exchange formats are out there, for which you will need other tools. These include SDTS, DLG, AutoCad, Mapinfo, etc.

More details in class...