Using Digitizers for drawing Maps

by Ken Swaggart W7KKE and WB4APR

With the help and inspiration of Ken W7KKE, MAPFIX.bas now lets you rapidly digitize maps and see the map on the screen as you draw it. Most of the instructions on using the digitizer within MAPFIX are included in that program. But the following is a more detailed set of set up ideas and cautions.. A common Microsoft SERIAL PORT mouse can also be used as a digitizer! See MOUSE.HTM.

The program should work with any Digitizer that outputs individual POINT coordinates in the format XXX,YYY,C. Where XXX and YYY are ASCII numeric values from 3 to 5 digits in length, and C may contain ASCII characters indicating the status of the PEN, Mouse, or Buttons on the mouse. The digitizer should operate in the POINT mode, so that a data point is only output when the operator presses a button or puts the PEN to the digitizer surface. The characters included in C are only used, if they end with the numeral "3", which is the 4th button on a 4 button digitizer mouse. With this type of mouse, you can use button 1 for adding points (the default mode), or button 4 to move the cursor with no action...

The program is set up to operate at 9600,N,8,1. To use the digitizer in MAPFIX, you must issue the FILES-OPEN command to OPEN the COMM port for the digitizer. Once the plotter is initialized, entering a point with the digitizer will always ADD a new point immediately after the current point indicated by the small white circle. Use EDIT-BEGIN to begin a new map feature with the Digitizer. This command prompts you for the name of the new feature and then will use the first tablet point as the STARTing point. All future clicks of the mouse add to this feature. You can also use the traditional EDIT-NEW comand with the mouse, but you must FIRST move the cursor to the starting point before doing EDIT-NEW. MAPFIX has HOTKEYS F4, F7, F8, F10 etc for beginning new features with a single key stroke.

  1. Place a map, or map section, on the plotter. It should be a Mercator projection with lat and long lines parallel with edge of plotter. MAPFIX will calibrate itself with the location of the map, but the map must be alligned so that a LAT line gives the same Y reading on both sides of the digitizer surface.

  2. MAPFIX aligns to the scale of the MAP by having you choose a lat/long in the vicinity of the upper left map corner and the lower right corner. These points are used to calibrate the plotter surface to the map. If your map is not a perfect MERCATOR, you can minimize the error by NOT choosing the extreme corners of the map, but choose points closer to your area of operation, say in the center of the upper left Quadrant and the center of the lower right quadrant.

  3. Run MAPFIX. To start a NEW map from scratch, type NEW when asked for a map filename. You must then select the LAT/LONG of your origin for your map and a scale in Pixels-per-degree. Note that finer and finer resolutions make smaller and smaller maps since there is a limit to the data values stored for each data point. When asked for a LAT/LONG in decimal degrees, decimal fractions are fine. IE: 35.6 or 124.55, etc. When asked for LAT/LONG in degrees and minutes, separate the degrees and minutes with a COMMA such as DD,MM.xx where minutes can be entered with decimal fractions if needed.

  4. Each map feature prompts for a feature name to ease in any debugging. Then just point to each position you wish to digitize. The program beeps and displays the converted data on the screen. After each point is added, any other MAPFIX command may be used. In otherwords, if you dont like a point that you just entered, just hit EDIT-DELETE, or EDIT-MOVE to MOVE it!

  5. Add Labels to the map at any time by moving the cursor to the desired map location, and pressing LABELS-ADD. Remember that the names are right justified so that the label will appear to the left of the point specified.

  6. Remember to save your map occassionally using the Ctrl-S command. After each save, you can just continue on with the next point, or QUIT the program. If things get screwed up, hit the SPACE bar to re-draw the map. If they are still screwed up, consider saving the map, and using an EDITOR to check things out and fix them according to the definition of a map given in README.MAP.

    NOTE: APRS and MAPFIX have troubles with a feature with only one point. They are seen as straight lines to the ORIGIN. Occassionally these get in there and you must remove them with a DOS text editor. If you try deleting them on-line within MAPFIX, you may delete whole other features and loose a lot of points. Sometimes these problem features are generated when you try to digitize a point which results in a ZERO value of X. That really screws things up! Be careful around the yellow vertical line that is the X origin! The C command scans the file and gets rid of single point anomolys. Also, if you can hook one, then EDIT-KILL will work to kill it.

  7. To add your new map to APRS, add the map file to your APRS MAPS directory, and then use an EDITOR to add the MAPNAME, center decimal coordinates, and range to the desired MAPLIST.xxx file. You may need to suppress some of the existing maps in the distro version of MAPLIST.xxx, by placing a * at the beginning of the map name, in order to keep the total number of active maps in your list below the 170 limit. Remember that you must place the new map in the proper order (more detailed maps must follow bigger maps that cover the same area) to get the right map to display when you have overlapping maps. While running APRS, if maps overlap, you can temporarily look at a map beneath a map by hitting MAPS-ALT. Then remember to fix the order of the maps in your MAPLIST.apr file later on to customize the list to your satisfaction.

MOVING THE PAPER MAP ON THE TABLET, OR RESETTING THE TABLET TO ANOTHER MAP

This is surprisingly simple! FIrst do a FILES-SAVE to save what you have already (in case Murphy drops by). Then without even stoppping the program, just place the new paper map on the digitizer and do another FILES-OPEN. MAPFIX will re-set the coordinates to the new map, and you can just keep on digitizing! This is neat, when you have 4 or 6 of the 24,000 scale maps that you are going to use to build ONE APRS map file. This capability is also very useful if you are using a 12inch by 12 inch digitizer tablet and need to move a single paper map 4 times to get all the data off of it!

CALCOMP DRAFTING TABLE MODEL 23360 (Used by WB4APR)

Use the onboard menu labels and mouse button 0 to configure the digitizer as indicated above and in the prompts within MAPFIX. I set it up for 200 LPI since that is more than adequate. Plug in the serial port, run MAPFIX.bas and start drawing! Do not get too fussy with lots of dots, remember that there is a 2999 point limit in APRS, so don't waste points with fancy curves where three points will do!

MOUSE: Notice, that a standard Microsoft SERIAL COM port mouse can be used as a poor-mans-digitizer! See MOUSE.HTM

SUMAGRAPHICS MMII 1812 digitizer tablet

Use the sumagraphics SEND.COM program to configure the tablet as follows:

SEND /1 /S96 /Czaz8c8cFBe

For more info on these tablets contact W2g3zfj@unix.asb.com and/or WJ8T snabkey@wingsbbs.com.

CALCOMP Model 4110 Plotter (Used by W7KKE)

Data is serial ASCII, even parity, with 4 characters of x position and 5 characters of Y. W7KKE thinks the 1st Y character is pen status. (if so, he is gonna have to modify MAPFIX to make it work)

Power input is pin 24 +12vdc at 290-300 ma. Pin 25 is power return.

Data Ranges: X: 0=left 4000=right y: 0=bottom 4000=top

Pen status: 0 = point mode 1 = run mode, pen down 9 = run mode, pen up

Set the "A/B" switch on back next to the D25 plug to B for POINT mode

Pin connections:

1    NC
2    +/- 15 v RS-232 data output from plotter.
3    + 5v from board (probably for some original interface device)
4    "             "                      "
5    0/+5v TTL data output
6    "                "
7    Ground (data return)
8-11 baud rate.
12 - 23 Unknown. Appear to be open.
24   +12 vdc  power input
25   ground

BAUD RATE PROGRAMMING PINS:

BAUD RATE 8 9 10 11 (X = connection to GND) 1200 . X . . 4800 . X X . 9600 . X X X (use this for MAPFIX.bas)

TEKTRONIX 4957 GRAPHIC TABLET (used by WA1VJH)

INITIALIZATION STRING: ESC Z, ESC Q, ESC M1, ESC F3, ESC C0, ESC x

ALSO, MAPFIX.BAS WILL HAVE TO BE MODIFIED AS FOLLOWS TO ACCEPT THE DATA STRING FROM THE 4957: Use the SEARCH-FIND command to find them

FROM: digix1 = 5000 - VAL(LEFT$(a$, 5)) TO: digix1 = 5000 - VAL(MID$(a$, 2, 5)) FROM: digiy1 = VAL(MID$(a$, 7, 5)) TO: digiy1 = VAL(MID$(a$, 8, 5)) FROM: digix2 = 5000 - VAL(LEFT$(a$, 5)) TO: digix2 = 5000 - VAL(MID$(a$, 2, 5)) FROM: digiy2 = VAL(MID$(a$, 7, 5)) TO: digiy2 = VAL(MID$(a$, 8, 5)) FROM: x = 5000 - VAL(RIGHT$(a$, a - 1)) TO: x = 5000 - VAL(MID$(a$, 2, a - 1)) FROM: y = VAL(MID$(a$, a + 1, B - (a))) TO: y = VAL(MID$(a$, a + 2, B - (a))) FROM: Btn = VAL(RIGHT$(a$, 1)) TO: Btn = VAL(MID$(a$, B + 1, 2))

ALSO NOTE THAT THE 4957 BUTTON NUMBER 3 WILL FUNCTION IN PLACE OF THE DESCRIBED MAPFIX BUTTON 4 DUTIES. DE GARNET/WA1VJH


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