Revised 22 November 1996

Back in Nov. 1995, I ordered a 1:2,000,000 USGS CDrom in DLG optional format.
The CD I received was structured differently than the format expected by the
MAKEMAP1.BAS program (one of the 'APRS' standard programs used in map making).

The CD was dated 7/95 and the files containing DLG data were not grouped by
region, rather by state (i.e., DLG data for Washington state is in file
\DATA\DLG\WA ). Further, the DLG data was not in a Latitude/Longitude format
as used by the APRSdos mapmaking programs (MAKEMAP and MAPFIX) but rather in
x/y grid offsets.

When I posted a note to this effect on the SIG, it was greeted with mostly
silence except for one or two 'you ordered the wrong CD'  or 'too busy'
replies.

Rather than be dead in the water, I have since taken MAKEMAP1.BAS and
CONV100C.BAS and modified and added new code to produce a new pair of chained
programs which handle the new 1:2,000,000 CD data. One program is about 27K
and the other 10K in length and require QBASIC to run.

I have since revised these programs (NU2MG30.ZIP is version 3.0, the latest
release) to improve the accuracy of the x/y grid to lat/lon conversions and 
allow the option for producing maps with only single catagories of features.
For example, this permits creation of maps with only boundaries represented, 
but be forewarned, the USGS data for boundaries includes not only state and 
county lines but also boundaries of Indian Reservations, National Forests, 
PublicLands, National Parks, etc. All this 'chaf' must be removed using 
MAPFIX to produce an uncluttered map.

Altough I am willing to share these programs with anyone, and anyone can
freely redistribute them, I have not rigorously tested them to a professional
level.

The programs are chained together, so it is an easy straightforward process to
make maps with them. Several questions are asked and then the programs
extract the appropriate state DLG data from the CD, unblock it, convert it
from the x/y form back to the old 2MEG form, and then process the points
into an APRS format. MAPFIX can then be used to add labels and reduce the total
point count down to 3000. Starting from scratch, it takes a 20MHZ 386SX about
a hour to crunch the data to a form suitable for MAPFIX. Status responses are
posted on the terminal to allow monitoring of the process.

USING NU2MGA30.BAS TO GENERATE APRS MAPS

1. I suggest creating a new directory structure on your hard drive for your
mapmaking activities. I use:

\mapmakin            -   for NU2MGA30.BAS and NU2MGB30.BAS
\mapmakin\data       -   for the work files
\mapmakin\maps       -   for the map files

Once created, copy NU2MGA30.BAS and NU2MGB30.BAS into the appropriate
directory.

You might also consider putting your working version of MAPFIX into the same
directory. Ensure that QBASIC.EXE is in a directory pointed to by your PATH
statement in your AUTOEXEC.BAT file.

2. Place the USGS 1:2,000,000-Scale CD-ROM in your CD drive.

3. Type QBASIC /RUN NU2MGA30 <ret>

4. The questions posed by the program are straightforward. The following are
typical answers:

Enter pathname .... ?  c:\mapmakin\data     

[--Note use of full pathname--]

Enter state ?  md

Enter ... CD ROM drive  e: 

Enter a file name for results ... ?  maps\md2maacy   

[--  You can enter any directory and filename. The suffix .map will be added
I use {state}{2m}{area abbreviation} (i.e.,Maryland, 2MEG, Anne Arundal
County)]

Enter latitude ... ?    39,00

Enter longitude ...?   76,30

Enter map radius....     20

Skip ... points .... ?    y or <ret>

     [***NEW FEATURE***]

Single or Multiple Catagories (S/M) [M] M

[--  Responding S will allow you to make maps with only
     one catagory of feature (e.g.,only water features, only
     boundries, only railroads)]

Select ... categories ?   2

Are these files already in ... ?   n     

[--  The program extracts and unblocks DLG data from the
CD-ROM to the working directory for each category
specified in the previous response. Significant
processing time can be saved on subsequent runs if
these files are not deleted. But all catagories selected
must have been created in a previous run. (e.g., if you
created files for catagories 1-3 in a previous run, you
can answer y for any other map within this state using
those catagories)]

5. The program will now begin the mapmaking process. Status messages will be
displayed to show its progress. Toward the end, data will be plotted to your
display showing the map being created. During this process you MAY see a
program artifact (read - I don't know why it does it) which draws a line from
the screen center to the upper left hand corner. This line is not included in
the output file.

6. When completed, use the MAPFIX program to reduce the number of map points
and add labels. Its not as hard as it might sound. If you use MAPFIX18 or
earlier versions, the CTRL-KEY comands refered to in the HELP screens will
work. The latest versions of MAPFIX by WB4APR use pull-down menus for these
same commands. If you are learning MAPFIX from scratch, the new version might
be easier. MAPFIX is described in the APRS HELP files.

- The above map takes about 45 minutes to process on my machine to the point
it is ready for MAPFIX.

- If the region you are trying to map crosses state boundaries, the DLG data
for each state stops at the state line. You will have to process each side of
the boundary separately and use MAPFIX to merge the two maps. You can use the 
same center latitude/longitude and range for multiple maps (it doesn't have 
to be within the state you are curently processing) to simplify merging maps.

GOOD LUCK, If you have any questions, feel free to email me. If the 
difficulty is with NU2MGx30, please send your map parameters so I can 
try to recreate the problem. NU2MGA30 is not perfect, but it's better 
than nothing :-)

--

Ted Antanaitis WA7ZZB
email: tedant@pipeline.com

