Ham Radio 2000/Ham Radio 2000.iso/ham2000/packet/aprs75c/mapmakin.txt

Text File | 1996-04-14 | 21KB | 367 lines

MAPMAKIN.txt  7.5c         ALL ABOUT MAKING MAPS

NOTE: There are several other README\MAP files:

      MAPS.txt gives an overview and info on where to find maps
      MAPS-CD.txt tells how to make maps from the USGS CD ROMS
      MAPS-HST tells you how to make maps simply by driving around and
               saving a track history!

Anyone that is going to distribute maps should read the info in MAPS.txt.

OVERVIEW:  My general philosophy is to keep maps simple so that APRS
will run quickly on any PC machine, including 8088 laptops, and so that
maps can be made by anyone and distributed within the amateur community
without any license or royalty concerns.  You can even look at them
with a DOS text editor!  TO minimize disk space and to speed up map
drawing, APRS limits the number of points to 2999 and the number of
labels to 199; any more detail on one map just clutters the screen.
This does NOT limit overall map resolution, however, since APRS can
overlay maps of increasing resolution as you zoom in.  To see the street
level ability of APRS, Zoom in to the 1 mile range in the center of Idaho
Falls.


METHODS FOR MAKING APRS MAPS

There are several methods for making maps depending on the resources
available to the user.

  MANUAL     - Ruler and Pencil method.  Just use a pencil and home-made
               template to determine X,Y offsets from the origin in the
               upper left corner of the map.  Then use a DOS editor to
               enter the X,Y values into a map file.  Or use the cursor
               in MAPFIX to free-hand a map.  This is quite tedious to
               make the cursor on the screen match real world
               coordinates.  This method is best for sketching in local
               roads on existing maps.

  GPS REPLAY - This is the easiest way to add detail in your area.  Just
               drive around with your GPS, saving APRS track history
               files.  Whenever you want to save a particular point or
               intersection, press F8.  Then use MAPFIX to overlay these
               histories onto the screen for easy cursor drawing.  Or
               use the GPStoHST.bas file to convert an existing NMEA
               data file to APRS track history format.

  CD ROM     - Use MAKEMAP1.EXE to build a 32 mile map (or up to 50 mile
               in rural areas) directly from the single 2,000,000:1 USGS
               CD that covers the whole US.  See MAPS-CD.txt

               Use MK100K2a.EXE to build 2 and 4 mile maps directly from
               the USGS 100k CD rom for your area.  See MK100K2a.txt.

  OBSOLETE     MAPFIX can inport data points from the 2M CD
               at the state road level, and 2 to 4 hours of manual
               filtering is required to eliminate redundant point data.
               W7KKE wrote a program that converts the 100K CD data to
               the 2,000,000 format for MAPFIX.  But it also takes hours
               to process the data into a usable and meaningful APRS map,
               since USGS data is VERY fragmented.  See MAPS-OLD.txt


  AUTOCAD    - KG8GE has developed programs for building APRS maps to
               and from AUTOCAD.  See the section at the end of this
               file.

  DIGITIZER  - MAPFIX can accept input from a digitizer tablet.  This
               makes all points very accurate and is the FASTEST way to
               build a map!

  MOUSE      - MAPFIX can be initialized to use a serial-MICROSOFT-mouse
               as a poor mans mouse digitizer.  See MOUSE.txt

  IMPORTING  - This feature in MAPFIX lets you import into your current
               map, all or a selected category of features from other
               maps.  Re-computing of the Origin and scale is AUTOMATIC.
               This makes it easy to combine maps.  Take parts from
               adjacent maps to build a map centered on your location.

Look for the sections below that describe each of these methods.  The
manual method is described first, since it gives you the basic structure
of the APRS maps format.  Remember that all APRS maps are in DOS TEXT
format.

GENERAL CAUTION:  APRS maps are NOT intended, nor expected to fulfill
all map requirements but to simply help locate radio equipped mobiles
within their 20 or so mile radio range.  In most applications too much
map detail just slows everything down and requires megabytes of disk
space.  Similarly, too many map labels makes it hard to see callsigns.
Also, while driving along at 55 MPH and 30 second GPS updates, zooming
in below about 8 miles makes the map move so rapidly so that fine detail
is not needed.  Often, a straight line between intersections is just as
effective as a very detailed curvy map but only takes 2 points vice 20!
So concentrate on plotting the intersections accurately; if you want to
come back later and add more detail curves for artistic sake, that is
easy to do with the MAPFIX.bas program.


HOW TO MAKE APRS MAP FILES:   To see what maps are available to the
system, use the MAPS-BORDERS command discribed above.  If your local
APRS net does not have at least a 64 mile map, please contact me.   It
is also easy to shift the center and detail of maps to highlight your
area.  See the section at the end of this file for info on how to
center, convert and spawn new maps.


OVERALL APRS MAP FILE FORMAT:  In any map file, the first 8 lines define
the origin and scale.  Comment text is permitted on these first 8 lines
after the initial data value and a comma.  See the example map below for
Colorado.  The remainder of the file just lists X,Y points that form the
map features such as roads and rivers.  To end each such feature and
begin another, APRS uses a 0,0 entry.  The next feature begins with the
value of the line color, followed by the feature name.  At the end of
this file, is a 0,-1 which marks the end of points data, and the
beginning of the list of map labels.  Then there is a 0,comment line that
starts the LABELS section.  Use a DOS EDITOR to look at ANY APRS map file.


MANUAL DOS TEXT EDITOR METHOD:  Simply use a DOS editor to make a list
of points for APRS to use in drawing line segments.  Note that the
coordinates are listed as X,Y where X is horizontal and Y is vertical.
This is backwards from the usual order that we list LAT (vert) and LONG
(Horizontal), so be sure to put the horizontal (X) value first. You can
use any editor to prepare a map file.  Simply use a chart that has
lat/long references and select an origin beyond the upper left hand
corner of the area you want to cover.  That point is 0,0 and all points
are measured from there. (negative numbers are OK if you later add
points behind the origin, but the - is an extra character that slows
down file loading); similarly, an X value of 0 is not permitted since it
is used to indicate separations between the end of one feature and start
of another.


MAP SCALE:  Next choose an appropriate scale in pixels-per-degree of
longitude and latitude for the area you want.  Using a 350/640 pixel
display, I have found that 120 pixels per degree (2 pixels per  minute)
is excellent for large state maps.  I used 12 pixels per degree for the
USA.  By keeping the scale number an integer multiple of 60, you avoid
any future roundoff and truncation errors due to ZOOM functions and when
converting points from one map scale to another.  I have used 6, 12, 24,
30, 60, 120, 300, 600, 1200, etc.  It takes 1200 pix or more in order to
resolve city streets.  If you use too fine of a scale then you are
limited as to how far the map can extend.  Points should be limited to 0
to 1024 in Y and 2048 in X if you want to later use the MAPFIX
compression algorithm to speed map loading and minimize file size.

MAP RANGE:  Since APRS handles range scales as integer powers of 2, I
suggest making most maps about 10% larger than any given power of 2.
This is so that you can place the cursor near the center of the map, and
pretty much see all of it at once.  To make it easy to find map centers,
APRS shows them with a small Plus mark (+).

MAPLIST.xxx:   This file contains the list of all map files available to
APRS and decides which map is loaded based on the location of the
cursor.  The first 3 lines of the file also contain the default LAT/LONG
and Range for the first map loaded.  The program uses this default to
center the first map each time the program starts up (center of USA).
These values are ignored when a backup file is loaded using the
FILES-LOAD command, or when a registered user has saved his default
location in his CONFIG file.   The MAPLIST.xxx default location is also
stored in the #1 MAP HOT KEY so that you can instantly zoom out to the
default map for that list with a single key stroke.

ADDING MAPS:   To add a map to your system, look at the MAPLIST.xxx
file.  It contains a list of all maps useable by the system.  There can
be multiple MAPLIST.xxx files.  The MAPLIST.USA file comes with the APRS
distribution and contains all regional, and state maps, plus some
representative local maps.  You can either add your map to this file, or
add it to any local state lists that might be available.  Currently
there are complete MAPLIST.xxx map files for many states such as Calif,
Missouri, and Ohio.  The MAPLIST.OH file lists over 90 local Ohio maps!

     To add a map, simply add a line that contains the MAPname, LAT,
LONG, MAPrange, and comments.  The LAT/LONG are in decimal degrees and
describe the center of your map.  The MAPrange tells the system to load
this map if the cursor falls within this range of the center.  Actually
it is a little more complicated.  The given map will not be used until
the cursor location plus the current range scale in all directions fully
falls within the boundaries.

     Currently APRS can only use 170 maps in MAPLIST.xxx.  To make room
for new maps, but keep old ones handy for later use, You can place a (*)
at the beginning of a line to tell APRS to skip that map.  Also you can
add some comment lines at the designated space in the file (beginning
with *) and for each map so that you can keep track of your maps.  If
you have no comments for a map, you MUST place a comma at the end of the
line.

MAP HIERARCHY:  It is important to place maps in decending order.  The
last map in the list that contains the given cursor position will be
used.  If a larger map covering the same area as a smaller map follows
it later in the list, then the larger map will always be found last and
will be used, instead of the desired smaller map.  You can see the this
effect, by using the MAPS-HIERARCHY command.  If maps overlap in your
area, use the MAP-ALT command to temporarily see the map beneath the
present map.  You can also use the MAPS-OVERLAY command to overlay the
larger map onto the present map.  Using this feature, you could make two
maps of the same area and scale.  On one you could put rivers and roads,
on the other you could put counties, property lines, and grids.  Then by
listing the gridded map first in the MAPLIST.xxx file, it would always
be superceeded by the road map, but could be summoned up by hitting the
MAPS-ALT or MAPS-OVERLAY command!

MAP FEATURES:  APRS displays all map features by drawing lines from
point-to-point.  Each feature begins with 0,0 followed by the line color
and a name for the feature, followed by pairs of x,y points using the
scale you chose.  The feature name is not used, but is useful for
identification during editing.  In APRS, there is no limit on the number
of features, But the total number of points must remain below 2999.  The
MAPFIX.BAS program does, however, have a finite limit during map editing
(currently about 150).  The POINT values are positive to the right and
down.  The end of a feature is simply the 0,0 which starts a new one.
After the last feature, there is a special 0,-1 which indicates the end
of all feature information and the beginning of the labels list.

MAP COLORS:  APRS recognizes certain map colors for turning on and off
map features.  It typically uses most of the brighter colors.  You can
change the background color with the Tint command or dim all colors
using the MAPS-FEATURES-DIM command.  Map colors are automatically
dimmed when you ask for a MAPS-BORDERS display so that map edges show up
brightly.  Here are my standard colors.  The * indicates that the color
is uniquely recognized by the APRS FEATURES command:

 0 - Black (normal background)    * 8 - dark gray (Railroads)
 1 - dim blue (ferrys, etc)         9 - Bright Blue
 2 - dim grn (Admin areas, Parks) *10 - Bright Green (Interstates)
*3 - dim cyan (Rivers)            *11 - Bright Cyan (Big rivers, Coasts)
 4 - deep red (state roads)       *12 - Bright Red   (major roads)
 5 - dim violet (custom features)  13 - Bright Violet(special events)
*6 - dim orange (state/cnty lines) 14 - Bright Yellow (Cities,airports)
*7 - gray     (back roads)         15 - Bright White  (Labels and CALLS)

NOTE: In Europe, the convention is to make Autobauns color 13 (purple).

MAP LABELS:   Labels are drawn on maps at given lat/long coordinates.
The labels are listed at the end of each map (up to 199).  Each label
has a range scale associated with it, so that more labels can appear at
smaller ranges.  The first line in the labels list has a leading 0 and
then any any comments.  From then on to the end of the file, each line
consists of 4 fields separated by commas.  First is the label text (up
to 12  characters long) followed by the LAT, LONG and RANGE.  LAT and
LONG must be  given in decimal degrees.  The MAPFIX.bas program displays
the location of the cursor in decimal degrees for this purpose.  Labels
are right justified so that they do not overprint station callsigns
which are all left justified.   Since absolute LAT/LONG reference is
used, labels can be transferred without any change to any scale map.

Please note, however, that labels are printed on the normal EGA screen
24 line raster, so they can be off their exact location by almost a full
text line vertically, and one full character horizontally at higher
scales.  Take this into account when placing labels.

     You can also build APRS symbols directly into MAPS!  Instead of a
text label, simply make the first three characters of the label be a $
followed by the symbol character, followed by a hexidecimal number from
1 to F that indicates the desired color for the symbol.  The remaining 8
characters can be used for a conventional label at the same location.
For example, look at the VORTAC's (aircraft nav aids) that I added to
the ALASKA maps.  They are listed in the map file as
$VEANC,lat,long,rng.  The V is the VORTAC symbol, the E is hexidecimal
for 14 or the color yellow, and ANC is the label for the ANChorage
VORTAC as it will appear on the map.


MANUAL TECHNIQUE:  Once you have chosen an origin in the upper left hand
corner of your map, all map values will be measured from that point.
Most maps have LAT/LONG lines around the borders.  If you are using 240
pixels per degree for a state size map, then each LAT/LONG line
corresponds to a multiple of 240.  Simply mark on the borders of your
original map these values 240, 480, 720, etc.  Then make a smaller
template which matches the size of one square of LAT/LONG lines.  Draw a
finer grid of lines every 10 pixels on the template.  Then to locate the
coordinates of any point on the map, simply orient the template with a
major LAT/LONG square, and interpolate the point within the grid on the
template which represents a 10x10 pixel area.  Use a text editor to add
these numeric values into the map file.  Every point on the map can be
identified by a pair of X,Y numbers.  Remember that these offsets are
from the origin for THIS map and scale.  For transfering features from
one map scale or origin to another, use the MAPFIX.bas IMPORT command.
Map labels, however use complete LAT/LONG values, so they can be freely
moved among maps.

CAUTION: since many highway maps are Lambert Conformal instead of
Mercator projections, use the center square in your map for making the
template to minimize errors.  Further, be careful of highway maps that
only have tick marks along the borders for LAT/LONG. If the map is not a
Mercator projection, then you cannot just draw a straight line from left
to right connecting latitude marks.  Longitude lines are straight on a
Lambert Conformal, but not latitude lines!


CUSTOMIZING TO YOUR AREA:  One way to begin customizing maps to your
area is to take one of the existing maps and add roads and features in
your area.  Since all APRS maps are limited to 2999 data points,
however, many are already just about full.  The following sections
describe how to spawn maps and convert points from one map to another so
you will have room to add your own detail using the very powerful
MAPFIX23.EXE program.


MAP EDITING USING MAPFIX23.BAS/exe:  Using this program, you can do just
about anything to a map, adding, deleting, moving points.  Importing points
from one map to another, etc.

  0------------------    0---------------------    0------------
  |         |       |    |         ---------- |    |           |  0-----
  |         |   *   |    |         | MAP C  | |    |           |  |
  |         |       |    | -----------      | |    |        -----------
  |         --------|    | | MAP B | |      | |    |     *  | MAP D   |
  |        *        |    | |       |*|      | |    |        |  |  |   |
  |                 |    | |       --|------- |    |        |  | *|   |
  |                 |    | |         |        |    |--------|--|  |   |
  | MAP A           |    | -----------        |             |---------|
  |                 |    |                    |                   |
  -------------------    ----------------------                   ------

  NEW CENTER & RANGE     MAP SPAWNING/CONVERSION      MAP IMPORTING

MAP SPAWNING:  In the figure above, map A is the original map with the
origin at 0.  Using 120 pixels-per-degree resolution, all points within
a square area 8 degrees on a side (about 400 miles) can be resolved with
pairs of 3 digit numbers.  As the number of points in such a regional
area map fills up towards the 2999 limit, it is necessary to start new
smaller area maps such as B, C, and D above to make more room.  Spawning
a new map using MAPFIX.bas is easy.  Simply use the CHANGE-CENTER and
CHANGE-RANGE commands to re-draw the white map border to the location you
want, then use the TASK-TRIM command to remove all points outside of that
area.   Next use the CHANGE-ORIGIN command to change the origin closer
to the new upper left corner and give a new scale to permit higher
resolution.  Finally, begin adding more finer detail using what ever
technique you intend to use.  Then save the new map and add its name to
the MAPLIST.xxx file.


IMPORTING AND COMBINING MAPS:  The TASK-IMPORT command will import all
points of a selected category of features from other maps into the
current map. This can be used to build large maps from small ones, or to
build new maps from pieces of other ones.  See MAP D above.  In this
process, all points from the selected map that fit within the WHITE
border of the current map, are imported.  For each pass, you specify the
source map, and what category of features to import.  Select the
category by the color number; 6 for boundary lines, 10 for interstates,
11 for coastline, etc.  Conversion of the data to the new ORIGIN and
scale are automatic.

PIXELS-PER-DEGREE:  Although my early regional maps used 120 pixels per
degree, most of the newer maps generated from my CD rom use at least 450
to 600 pixels-per degree.  This gives finer detail resolution on the
smaller 64 mile maps.  You can use 1200 ppd to resolve down to large
city blocks, but to get them accurately, you should consider 3000 ppd
which can resolve down to about 100 feet.  Notice that as you increase
the number of pixels-per-degree, you also reduce the maximum size that a
map can cover.  This keeps the numbers from getting too large and
causing an overflow condition.  A 1200 ppd map should be used for map
areas less than 50 miles and so forth.  To get city streets at 3000 ppd
the map can only have an 8 mile radius.

For more information see MAPFIX.txt

AUTOCAD MAPS!   Jim Krist KG8GE has done a marvelous job of writing
programs to use AUTOCAD to make APRS maps.  He has done every street in
the town of MARION Ohio.  HIs program is named PLT2MAP and permits you
to use a CAD plotter to make AUTOCAD maps and then convert them to APRS.
Registered copies of his software can be obtained for $25 from him at
315 Hane Ave, Marion, Ohi0, 43302.