The following instructions will only work if you DEM is in USGS
format. Most DEMs from the USGS are not in USGS format (go figure…)
– it is in SDTS format (but the USGS is also now producing DEMs in
other formats including ArcGrid). If your DEM is in SDTS format
(Spatial Data Transfer Standard), you will need to use the Import
SDTS Raster to Grid tool in ArcToolbox.
After you download the DEM, you need to unzip it. Once it is
unzipped, you can import it into ArcGIS.
- Start ArcToolbox, and choose Conversion Tools – Import to
Raster – DEM to Grid. Read the Help information before you begin,
then follow the instructions
- The USGS DEM is the file that ends in .dem (e.g.,
3097420g.dem)
- Leave all the defaults as they are for now – we will talk about
these in class.
- For output grid, you can navigate to your personal folder and
type in a new name – this will be the final ESRI formatted DEM that
you will work with, so give it a good name, like the name of the
quad map it represents (e.g., austin_west). But read this carefully
– you cannot specify a folder that has spaces in the folder name;
in fact, no folder in the entire path on the computer can have
spaces in it (don’t ask me why). So the folder path to this new
grid needs to be something like
C:tempedwards_groupdemaustin_west
- Once the importing process is done, take a look at the results
in file manager or explorer – notice that there are now two
folders, one called the name that you gave the grid (e.g.,
austin_west) and one called info. This is an ArcInfo
formatted GIS data set.
- Next add the new grid to a data frame in ArcMap.