
              Watershed Boundaries and Digital Elevation Model

                             of Oklahoma 

           Derived from 1:100,000-Scale Digital Topographic Maps

             U.S. Geological Survey Open-File Report 95-727

Directory   /software/imdisp  example.txt file:

   This file contains an example of the use of IMDISP on an MS-DOS
computer.  The example assumes the software has been installed
properly, according to the IMDISP software documentation.  The
software will need to be installed on the computer's hard disk, and
the directory in which it is installed should be in the MS-DOS search
path. 

   First, make the CD-ROM drive the active drive and change to the
"\data_pd" subdirectory using the "cd" command.  Then type the
following sequence of commands (explanatory notes enclosed in
parentheses should not be typed):

imdisp
file okdem.lbl     (look at the DEM elevation file)
set swap           (needed for okdem, but not other data sets)
set dnlo 65        (for areas of low relief, set dnlo and dnhi to
set dnhi 1500       values near the low and high elevations in the area)
display sub 25

cursor             (position cursor using mouse or arrow keys to
                    center of area of interest)
display cen sub 1  (if a larger area is needed, increase subsampling)

file okshdrlf.lbl  (now look at the shaded-relief data set)
display cen sub 1

file okflowac.lbl  (now look at the flow-accumulation data set)
set dnhi 5
display cen sub 1  

file watershd.lbl  (now look at watershed boundaries)
display cen sub 1


Additional notes: 

   Increased subsampling with the display command displays larger
areas, but lines such as the watershed boundaries and flow
accumulation become discontinuous as pixels are dropped out.
Continuous data sets such as "okdem" and "okshdrlf" may be displayed
at large subsampling intervals, but the "watershd" and "okflowdr" data
sets do not display well at large subsampling intervals.

   The "swap" command is needed for multi-byte images because the byte
order in the ".bil" files is the reverse of what is used on
IBM-compatible personal computers.  The "okdem" data set is the only
multi-byte image on this compact disc.

   Additional information on the use of IMDISP may be found in the
"imdisp.doc" file, which is included in the
"/software/imdisp/imdis79g.exe" archive file.
