RSGIS Unix Pages

ArcView 3.2 comes with a SDTS to ArcView Grid translator program called sdtsraster2grid. However, the USGS has slightly modified their SDTS files since the development of the translator, and ESRI has only seen fit to make adjustments to their Windows platform products. But with a sneaky workaround, we can still use the Unix-based translator without having to take our data to Windows and back again.

After you've downloaded your SDTS DEM  files, they will likely be in a tar.gz file, such as 1633665.DEM.STDS.TAR.GZ. First you must use gunzip to decompress the file, and the tar command to extract the files from the archive. We recommend you create a new directory and copy the .tar file to it so as to keep track of your files.

After you've extracted the files from the .tar archive, you should have around 18 or so files with the .DDF extention on the end that look similar to this:

9067CATD.DDF
9067CATS.DDF
9067CEL0.DDF
9067DDDF.DDF
9067DDOM.DDF
9067DDSH.DDF
9067DQAA.DDF
9067DQCG.DDF
9067DQHL.DDF
9067DQLC.DDF
9067DQPA.DDF
9067IDEN.DDF
9067IREF.DDF
9067LDEF.DDF
9067RSDF.DDF
9067SPDM.DDF
9067STAT.DDF
9067XREF.DDF

(There should be a four digit prefix number followed by a four-character filename.)

Now comes the tricky part. Using a text editor (such as emacs), you need to open the file with IDEN in the filename, such as 9067IDEN.DDF in the above example. Find the following text somewhere in the body of the file:

SRPE: SDTS RASTER PROFILE and EXTENSIONS

Now, without changing anything else, carefully replace it with the following text:

SDTS RASTER PROFILE and EXTENSIONS<space>

[Don't actually type <space>, but be sure to place a space after the S in EXTENSIONS.]

Once you've made the changes, be sure to save the file with its original name. Now you're ready to run the sdtsraster2grid translator program.
 
 

The sdtsraster2grid translator program uses the following syntax:

/auto/esri/arcview3/bin/sdtsraster2grid /<filepath>/<fourdigitprefix> <gridname>

[where <filepath> represents the full path of directories where your .DDF files reside; <fourdigitprefix> represents the number common to every file in the set, and <gridname> represents the name you want to give to your resulting ArcView grid.]

For example, let's say I placed the files in a directory called cache under my home directory and wanted to translate them into a grid called cache_dem, I would type the following at the prompt from within the directory where the .DDF files are located:

/auto/esri/arcview3/bin/sdtsraster2grid /home/gia14/cache/9067 cache_dem

The translator will then run its routines, taking several minutes for larger files. Once finished, I have a new subdirectory labeled cache_dem.

I would next open ArcView, making sure that Spatial Analyst extension is selected. Adding a theme to the current view and selecting Grid Data Source will show the cache_dem grid coverage. If I open it, it will be added to the view as the familiar raster DEM.