To Create a Grid Surface From a DEM

DEM files come in several formats. You can import either USGS DEM, ESRI Arc Grid, or GeoTIFF files.

Tip: You can also import DEM files into an existing surface. For more information, see To Add DEM Files to a Surface.

Click Home tabCreate Ground Data panelSurfaces drop-downCreate Surface From DEM Find.
In the Grid Surface From DEM dialog box, browse to the location of the file.
Select the DEM (.dem), GeoTIFF (.tif), ESRI ASCII Grid (.asc or .txt), or ESRI Binary Grid (.adf) file. The filename is displayed in the File Name field.
Note: SDTS (Spatial Data Transfer Standard) DEMs are not supported in Autodesk Civil 3D.
Click Open.