You can use ArcGIS Spatial Analyst to convert a United States Geological Survey (USGS) GTOPO30 digital elevation model (DEM) to an ESRI grid format.

Click the USGS GTOPO30 link in the Related Information section to download a GTOPO30 DEM. This file comes as a .tar file, which contains the *.dem and *.hdr files. Both files are required for this operation.

1. Uncompress the TAR file using WinZip 6.2 or higher.-show me-

   Summary

   Data corruption may occur when extracting data with the WinZip compression utility.

   Procedure

   Open WinZip Classic. Select Options > Configuration > Miscellaneous tab. Uncheck the 'TAR file smart CR/LF conversion' box. The box will remain unchecked until you change it again. Unzip and import the data.  Some error messages and problems can occur if the 'TAR file smart CR/LF conversion' is checked. -show me- If the file has a .tar.gz extension, it needs to be unzipped twice. A. When the .tar.gz file is double-clicked to open, WinZip will pop up a box saying that the archive contains a number of files, and asking 'Should WinZip decompress it to temporary folder and open it?' Click No. B. Check the 'TAR file smart CR/LF conversion' box. Extract the .tar file from the .gz archive to the desired folder. C. Double-click on the .tar file to start WinZip a second time. Uncheck the 'TAR file smart CR/LF conversion' box, and extract the .tar file.

   WinZip Support

   
   
   
    If not properly configured WinZip can corrupt the files.
   
   
2. Change the *.dem extension to *.bil.
3. Open ArcCatalog.
4. Navigate to the *.bil created in Step 2.
5. Right-click on the *.bil, click Export, and click the Raster to Different Format option. Specify the location to which you will save the new grid, and ensure the Save As Type is set to ESRI GRID.
6. Open ArcMap and add the grid created in Step 5.
7. On the ArcGIS Spatial Analyst toolbar, click Spatial Analyst and select Options.
8. Click the General tab and set the working directory.
9. Click the Extent tab and set the analysis extents to Same as layer 'your grid'.
10. Click the Cell Size tab and set the cell size to Same as layer 'your grid'. Click OK.
11. Navigate to ArcGIS Spatial Analyst and select the Raster Calculator. Enter the following expression, substituting your grid for [in_grid]. Include the square brackets.
    
    

    CON([in_grid] >= 32768,[in_grid] - 65536,[in_grid])

    
    Click Evaluate.
12. The ocean areas (-9999) can be converted to NODATA using the SETNULL function. Insert the Calculation from Step 5 for [Calculation]. Include the square brackets.
    
    

    setnull([Calculation ] == -9999, [Calculation ])

    
    Click Evaluate.
13. Save the final output to disk by right-clicking the Calculation result from Step 6 and selecting Make Permanent.

• Convert GTOPO30 DEM data into a grid
  You can use ArcInfo GRID to convert a USGS GTOPO30 DEM to grid format while retaining the digital elevation data values. Click the link in the Related Information section to download a GTOPO30 DEM. This file comes as a .TAR file, which contains...
• UGSG GTOPO30
• Convert GTOPO30 DEM data into a grid
  You can use ArcView Spatial Analyst to convert a USGS GTOPO30 DEM to grid format while retaining the digital elevation data values. Click the link in the Related Information section to download a GTOPO30 DEM. This file comes as a .TAR file, whi...