Some notes on drawmap.  Updated on March 26, 2001.

First, how to build it.  Edit the Makefile if you want a copyright
notice on all of the maps you generate.  Then, simply type:

make

If you aren't on a Linux(TM) system, or similar Unix(TM) system, you will
probably end up giving up and deleting the whole mess.  Otherwise, you
should end up with eight executables:  drawmap, llsearch, ll2utm, utm2ll,
block_dem, block_dlg, sdts2dem, and sdts2dlg.  There should also be eight
formatted manual pages, whose file names end with a ".1" extension; and
eight unformatted manual pages, whose file names end with a ".1n"
extension.

Install things wherever you want.  On my system, the executables go into
/usr/local/bin, the manual pages with a ".1" extension get compressed
(with gzip) and go into /usr/local/man/cat1, and the manual pages with
a ".1n" extension get compressed (with gzip) and go into /usr/local/man/man1.
(You don't have to install both the ".1" and ".1n" versions if you don't
want to.  The ".1n" version is probably the most useful, since it allows
you to reformat the manual pages into various output formats.)

I have resisted the urge to hard-code any pathnames, library locations,
and what-have-you into the code.  There is one compile-time option you can
invoke by editing the Makefile.  If you provide your name, it will be
compiled into the program, and a copyright notice, with your name in it,
will be added to the bottom of each map you generate.  I am unsure about
the copyright status of a map generated by drawmap, since anyone else
can generate the same map using the same data, but the feature was easy
to add in, so I did.



Second, how to use it.  You need some data.  Once you have at least one
Digital Elevation Model (DEM) file, using drawmap is as simple as typing:

	drawmap -d name_of_your_dem_file

The output will be in a file called "drawmap.sun" and you should be able
to view it with image viewers like "xv" and "ImageMagick".  Sources of
downloadable data are listed in the manual page.  There is a lot of useful
information in the manual page; you might want to give it a read.
In particular, there are some usage examples near the end of the page.



Drawmap grew out of my curiosity regarding what could be done with the
available USGS data files.  It was originally intended just to play
with Digital Elevation Model (DEM) files.  Later I added processing
for Digital Line Graph (DLG) files, GTOPO30 files, and Geographic Names
Information System (GNIS) files.  Because of this history as an experimental
testbed, drawmap was never actually designed.  Instead, it grew
by accretion, with major sections being reworked from time to
time as I decided to try new approaches.  There have even been a
couple of top-to-bottom reworks, as I found it desirable to try a
much different approach to one thing or another.  The addition of
support for SDTS files considerably increased the complexity of the
program.  Thus, if you are looking for elegant structure and logical
design, you may be disappointed.  On the flip side, it is copiously
commented, and you should find it fairly easy to modify.  Keeping
straight all of the various translations and rotations of data can be
mind-numbing; but that pretty much goes with the territory when you work
on a program like this.

Also, in order to minimize its memory footprint, drawmap uses malloc()
to get the space it needs, and then uses pointers to access it.  I find
the resulting code much more difficult to work with than code that
simply allocates a 2-dimensional array and uses two index values to
access the data.  Thus, if I plan to do a major rework on the code,
I sometimes convert it back to using arrays, do what needs doing,
and then convert it to using pointers.  Some people prefer to
define macros that simulate arrays on the one-dimensional malloc()
memory.  Others may prefer to define C++ objects to hide all of the
messy details.  I like simplicity.  Your mileage may vary.

I have a to-do list of things that would be nice to have.  Near the
top of the list is to improve the handling of text.  The routine that
adds text annotations to the image is very crude.  I cobbled it together
one night because I needed the capability to add cursors and text in
order to test out some algorithms, and I have never gone back to improve
it.  Only two bitmapped fonts are available, and they can only be
printed horizontally.  It would be super cool (and perhaps even swell)
to have a bigger set of prettier fonts that could be scaled and rotated.
This would be particularly nice for plotting hypsographic contour lines
with the traditional elevation numbers printed along selected contours.
(Although trying to do that sort of thing automatically would be a
challenging task, indeed.)

It would also be a good idea to try to make the thing portable.  At
present, it has only been compiled (by me) under Linux.  Based on past
experience, I assume that it will readily port to other Unix systems.
However, porting it to Windows(TM) might not be fun.

Another possibility would be to re-write it to be an X-Window
application.  This would allow some interactive features to be added
and would also provide instant access to a large set of fonts and
drawing primitives.  However, there are already systems like that
available, and I am not sure I want to produce yet another big,
clunky, non-portable thingamabob that nobody uses because they
can't get the thing to compile on their machines.  I know how
disappointed I am when I go to the trouble to download something,
and then find out I need some large support package before I can
use the software.

If you like the kind of resolution available in a 7.5-minute
topographic map, you might want to look into the availability of
DRG files.  DRG files are scanned-in versions of the standard
USGS 7.5-minute map sheets.  The USGS sells these files on CD-ROM,
but they are also available on-line for some locales.  For example,
the state of Montana has a server providing all of the available
DRG files for Montana.  In fact, a number of states provide such
a service.  There are also a few sites that aren't tied to particular
states, but have a smorgasbord of files from various locations.

I hope you find drawmap both useful and fun.  Remember though, that it
is basically an experimental testbed, and not a commercial product.
Use it at your own risk.  Drawmap, and all associated software and
documentation, are provided "as is", and are licensed under the GNU
General Public License.  See the file "COPYING" for license details.

Fred M. Erickson
603 15th Street
Havre, MT  59501-5339

fme@ttc-cmc.net