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Text File | 1994-01-03 | 25.6 KB | 403 lines

HOW TO MAKE YOUR OWN MAPS (README.MAP) VERSION 3.07B distribution now includes the capability to use a DIGITIZER with the MAPFIX.BAS program so that you can draw a map on-screen using a digitizer tablet or drawing board! If you have a digitizerr, you can ignore 90 percent of this readme.map file. But you should still read it completely to get a full understanding of the structure and detail of APRS maps and how they work. GENERAL CAUTION: Many map makers have run up against the array limits in APRS in surprise. Here are the limits per map: 1000 map points, 99 Map labels, and 99 active maps. If you approach these limits, begin a new map! SECONDLY, APRS maps are NOT intended, nor expected to fulfill all map requirements. APRS maps are only intended to provide the user with a visual reference to where things are in a radio network. Once you see where a station is, and you want to see what street he is on, or what address block he is in, you should refer to printed maps of your area. Do not waste time trying to put too much detail into APRS maps! Similarly, don't try to label everything. Too many labels makes it hard to see callsigns. I just got back (thanksgiving 93) from my first long GPS mobile trip with a laptop, and can confirm that at 60 MPH and 30 second updates, I rarely ever went below the 8 mile scale and usually stayed at the 16 mile scale to see what was comming ahead. This confirms that in most cases a straight line between intersections is just as effective as a very detailed curvy map and only takes 2 points vice 20! So concentrate on plotting the intersections accurrately; if you want to come back later and add more detail curves for artistic sake, that is now easy to do with the latest version of my MAPFIX.bas program. SUCCESS!!! In Version 3.01, MAPFIX.bas can now ADD complete features while online; and in version 3.05 you can do almost anything with a map file! But In 3.07B not only can you start a file without beginning with a text editor, but you can also use a DIGITIZER to draw the map directly from a map! Without a digitizer, you should probably always start with a text editor and and a pencil to identify the point values to place roads geographically correct. But after the major roads and other geography is on the map, MAPFIX makes it a snap to eyeball in smaller roads and to smooth out points, or to add tiny jogs in the roads or shoreline. NEW IN DISTRIBUTION 3.00: Added a comment field for each map in MAPLIST.map file to help you keep track of what maps are what. If you do not add a comment you MUST add a COMMA on the end of the line as a null entry. Also the MAPFIX.bas program now has a routine to list MAPLIST.map and to show all map borders. Both of these changes are incompatible with earlier versions. NEW in DISTRIBUTION 2.13: The format of the MAPLIST.map file changed so that you can SUPPRESS any map in the list. This keeps the number of maps below the maximum of 60 that APRS can handle at a time, but keeps the map in the list for easy activation. Just use an editor to put a (*) at the start of a map you want to skip. NEW IN DISTRIBUTION 2.11: The MAPFIX.BAS program can now be used to ADD, MOVE, and DELETE map points and also to Add map LABELS! Also, Ken Swaggart, W7KKE in Foster City, CA has written a QBasic program that takes map points directly from a CALCOMP 4000 series plotter. See README.PLT and his maps! (NOTE, his program is probably obsolete now with 3.07B) Lastly, I have renamed many maps so that all map names begin with the two- letter state abbreviation so that they sort better alphabetically. HOW TO MAKE APRS MAP FILES: To see what maps are available to the system, use alt-M. This command draws the boundaries of all map files and shows you the areas covered by detail maps. The colors of these borders are proportional to map size. Some of these maps are very detail, and some are just "starter" maps that I have made to give new users in those areas a basic map outline from which to add their own detail. If a map boarder is shown, but the map does not appear, then the mapfile is not on your disk. If the mapfile is there, but its boarder does not show up, then it is not listed in the MAPLIST.map file. Since I live in Maryland, you will notice that we have a lot of detail maps already put together for users in our area. Notice how maps of finer detail can exist within the same area. Zoom into my neighborhood at 3910N 07636W and see my neighborhood detail using 1200 pixels per degree. Also see some of the San Francisco maps made by W7KKE. He has used 2400 pix-per-deg on some maps. I try to provide a starter maps for each region. These region sized maps should contain only statelines and interstates, or you will run out of room (limit 1000 points and 80 labels per map) See the section MORE ABOUT MAPS at the end of this file for info on how to center, convert and spawn new maps. Slowly other APRS users are beginning to produce maps. Here are some good map makers: W4NMK Black Mountain NC N4WJQ @ WA4TFZ.VA Charlottsville VA W9LZQ Onalaska WI KD1E @ N8NNN.#SEMI Michigan MI N3FKV Waco TX KD6MKS Silver Lake CA W7KKE @ KA6EYH#nocal San Francisco CA wrote PLOTTER and GPS cmds KB5YRZ @ N5SSY#METLA New Orleans LA N4FOR Savannah GA KB8JXO @ W8CQK.#CMH.OH Columbus OH WB5DTW SanAntonio TX KA7UUS @ K7BUC.AZ Tuscon AZ BEGINNING A MAP FILE: 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. BUILDING A MAP: Map files are put together using 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 well 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. Since EGA graphics has a 350/640 pixel resolution, I have found that 120 pixels per degree (2 pixels per minute) is excellent for state size maps. I used 6 pixels per degree for the whole US, but should have probably used 12 for better resolution. 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 with values greater that 999 should be minimized and no values should be bigger than about 1100 or there is a chance APRS will crash on very zoomed-in maps. The further you zoom in, the larger the values become until you get an overflow error. MAP RANGE: Since APRS handles range scales as integer powers of 2, I suggest making most maps slightly larger than any given power of 2. This is so that you can place the cursor in the center of the map, and pretty much see all of it at once. If you make the size of your map just under a power of 2, then you can never see the whole map at that range. Going down a scale permits you to see all of the map, but only a smaller portion of it at a time. To make it easy to hit the center of a map with the cursor, I usually make my maps with a range scale about 10% larger than an even power of 2. MAPLIST.MAP: This file contains the list of all maps available to the APRS program and decides which map is loaded for every location of the cursor. It also contains the default LAT/LONG and Range for the first map loaded. The program uses the default LAT/LON to center the first map each time the program starts up (on unregistered users). This map is distributed as the whole USA map since it is also good for use on HF. These values are NOT used when a saved backup file is loaded using the CTRL-L, or when a registered user has saved his default values in his APRSconfig file. So to force APRS to start up at your location, you can either 1) change this location in the MAPLIST file, 2) move the cursor to your location and use Ctrl-S to save a backup file with you at the center, or 3) if you are a registered user, save a config file. To change the default in the MAPLIST file, change the first three lines to your area as soon as you like. Keep a virgin copy of MAPLIST.map so that if you mess up the file, you have a clean starting point again. As of version 2.05, you can instantly zoom out to the default map (the USA) using the Shift-End key. This is useful for doing a quick glance at HF mobiles that might be comming in through a GATEway! ADDING MAPS: To add a map to the system, look at the MAPLIST.map file. It contains a list of all maps available. Add a line that contains the MAPname, LAT, LONG, MAPrange, and comments. The LAT/LONG are in decimal degrees and describe roughly the center of your map. The MAPrange tells the system to load this map if the cursor ever 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. This keeps you from being on a postage stamp sized map of someone's neighborhood when you are zoomed out to see the whole US! HINT - so that your detail map seems to blend in with the next larger map, add enough rough features and points to your borders to surround your fine detail area with crude detail out to MAX Range beyond. Then when the screen centers on a point near the edge of your fine detail, your map doesn't just stop but includes crude detail to all edges. Currently APRS can only use 60 maps in MAPLIST.map. As of version 2.13 you can place a (*) at the beginning of a line to tell APRS to skip that map. This way, you can make room for new maps, but keep old ones handy for later use... Also you can add some comment lines at the designated space in the file (beginning with *) so that you can leave notes as to what that particular file represents. As of version 3.00, there is also a comment field for each map. If you have no comments, use a comma to end the line. MAP HIERARCHY: It is important to place maps in decending order. The last map in the list that shows 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. If maps overlap in your area, hit shift-Home to temporarly see the map underneath (ver 2.05 and later). 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.map file, it would always be superceeded by the road map, but could be summoned up by hitting shift-home! 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 name is not used, but is useful for identifying features during editing. In APRS, there is no limit on the number of features, just on the total number of points used to define them (1000). Since the MAPFIX.BAS program does, however, does display these feature names during on-line editing, there is a limit of 99 in the array used to hold these names temporarily. 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 certain map features. For this reason it is a good idea to use my standard colors. I made most map features using the brighter colors since they are easier to see on a color monitor outdoors. In recent versions, you can change the background color with the Tint command under Features, and in version 3.00 the map colors will be dimmed when you ask for the Map Borders display (alt-M). I will add a DIM command in the next version, so you dim the colors if you like. Here are my standards, the * indicates if they are uniquely recognized by the software: 0 - Black (normal background) 8 - NOT USED 1 - dim blue 9 - Bright Blue 2 - dim green *10 - Bright Green (Interstates) 3 - dim cyan *11 - Bright Cyan (waterways) 4 - deep red (state roads) *12 - Bright Red (major roads) 5 - dim violet 13 - Bright Violet(special routes/events) *6 - dim orange (state/county lines 14 - Bright Yellow (Cities,airports) *7 - gray (back roads) 15 - Bright White (Labels and CALLS) MAP LABELS: Labels are drawn on maps at given lat/long coordinates. The labels are listed at the end of each map (up to 80). Each label has a range scale associated with it, so that not all labels are visible at all range scales. As you zoom in to finer and finer detail, you can make more labels appear. 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 plotted right justified. This means they will be plotted to the left of the given point. A way to visualize how a label will appear is to assume the label has a following period (.) and that the period is the location where the label will be plotted. 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 with out any change to any scale map. You may decide to change the range size so that the label shows up sooner or later on different maps. As of version 2.12, MAPFIX.bas has a command for automatically inserting new map labels at the cursor location. This greatly simplifies map making! EXAMPLE: The following map file constitutes a trivial state map of Colorado. The first 8 lines are the fixed format lines which define the origin and scale. Next are the features for the state borders and for Denver. Finally are the map labels. To see how this map looks, move the cursor to the center of Colorado on the US map and page-down to the 256 mile scale. 41.0, latitude origin (equates to 0,0 in) [Notice how comments can be on] 110.0, long of origin (coordinate system) [the ends of these first lines] 60, pixels per deg of lat/long [and 1st line of each new line] 39,LAT of map center (For ur reference only. Value in MAPLIST.map is what) 105.5,LON of map center (is actually used as the center and Range for maps ) 200,MapRange 4,minimum range (APRS does not use this, it now computes min range) * This single comment line can contain anything... more or less 0,0 6,Colorado state line 59,0 59,240 479,240 479,0 59,0 0,0 14,Denver city limits 300,68 289,77 300,85 311,77 300,68 0,-1 (0,-1 indicates end of map features) 0,Comments or notes... etc ( note that the 0, is required ) Colorado,40,105,200 Denver,39,104,100 NOTE: The 7th line showing a min range used to be important. Starting with a full scale map, each time you page-down (zoom in) you are doubling the value of each pixel lat/long value. If any of these numbers ever exceed the maximum permissible value of 2 byte integer math (32,000) then the program will crash. After version 2.04, APRS assumes that there will not be any data points larger than about 1100 and will not draw your map to a scale that would multiply this number too big. This is why APRS will not draw the USA map smaller than about 32 miles. Six pixels per degree for the USA map was a poor choice since the largest point value is still under 400 or so. So I could have used 12 per degree and still been below 999. This would have given me better resolution and would have permitted zooming in to 16 miles. MAPFIX.BAS: This QBasic program may be used to test and edit your maps. It helps you to quickly display single maps and to use the cursor to identify individual map point coordinates. It also has a readout of the cursor in decimal degrees which is required for locating labels and map Centers. Prior to APRS distribution 2.10 this program only allowed you to look at your maps. Now you can add, move and delete map points and save a new file. With 3.01, you can even add new features! In 3.05 you can also delete features and points. With 2.13 MAPFIX.bas can also add labels, and with 3.00, it can list maps in the MAPLIST.map file and also show all map borders. 3.07 allows you to overlay a GPS track history file over the map you are drawing so you can make your roads as accurate as GPS! 3.07P ADDS A DIGITIZER INTERFACE SO THAT YOU CAN DIRECTLY DIGITIZE ANY MAP! MAPCNVRT.BAS: This QBasic progarm may be used to convert any one map to a different LAT/LONG origin or different Pixels-per-degree resolution. Use it in conjunction with the QBasic editor for piecing together features from one map to cut and paste into another map. Say you are building a fine detail map, but want to use the statelines and interstates from a larger map. Just use the editor to remove all unnecessary points from the big map, keeping all the features that you want to retain and move to your new map. Then save it with a TEMPORARY name and then run it through MAPCNVRT.BAS to re-compute all of the map points. Then use this new file as the beginning of your new map. You can also use the point-add-delete function in MAPFIX.bas to fine tune these points. TECHNIQUE: See the sketch above (not available in text file) which shows how simple it is. Most maps have LAT/LONG lines around the borders. If you are using 120 pixels per degree for a state size map, then each LAT/LONG line corresponds to a multiple of 120. Simply mark on the borders of your original map these values 120, 240, 360, 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. Actually, if we all use 120 pixels per degree for state size maps, then it is easy to transfer features from one map to another without complex mathimatical computations. For transfering features from one map scale or origin to another, Use the QBasic program called MAPCNVRT.BAS which will re-compute all point values. Then use a text editor to re-do the LAT/LONG and range and to cut and paste the necessary map labels on the end. 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! SPECIAL EVENTS: Conversly, absolute accurracy is only important if there will ever be a GPS or LORAN-C station involved in your net. A map with little relationship to true LAT/LONG is perfectly useable in all APRS applications as long as all stations in the net are using the same map and no one is using GPS. So feel free to draw quick simple maps for special events even as small as a few square blocks without worrying about exact LAT/LONG. Objects on one station screen will still be in the same location on all other screens! Use the Chess board example at 25N 90W to play chess on the air! But GPS is comming, be prepared! (PACCOM TNC's now come with a GPS interface built-in!) MORE ABOUT MAPS PART 2 FLASH!! With the advent of low cost GPS, most mapmakers are now beginning to add LAT/LONG to most new maps. Our 7-11 convenience store maps now even include map booklets which have a LAT/LONG grid on every page! The grid lines are 5 minutes apart which is exactly 10 pixels if you use 120 pixels per degree as I do for most APRS state maps. This means that each grid square is a 10x10 pixel area from which map coordinates can be typed directly into a text editor without any drafting aids! Simply note the grid coordinates of the corner of each page in the book and start entering points! Rumor has it that the comparable convenience map maker on the west coast is also now making map books with LAT/LONG grids. NOTES ABOUT STARTER MAPS: The starter maps that I have provided use a scale of 120 pixels per degree and have an origin that is suitable for about a 400 mile square area. This area usually covers from one to several states and is good for area maps. With the whole map visible, one pixel represents abt .25 mile resolution. The first step in customizing maps to your area is to take the starter map and start adding roads and features in your area. Since all maps in the APRS system are limited to a maximum of 1000 data points, however, these large area starter maps can usually contain only the interstate roads, the state lines, and major rivers and 4-lane highways. This is perfect for most VHF applications. But as more and more people add detail closer to home, smaller maps need to be "spawned" off to make room for more detail. The following sections describe how to spawn maps and convert points from one map to another. MAP CENTERING: Most of you do not live in the middle of a starter map and so your detail will be off center. To make a more pleasant transition as you zoom into your area using APRS, you may want to simply change the center and range of the starter map to be centered on your area with a range suitable to the amount of detail you have added. To do this, simply edit the line for your starter map in the MAPLIST.map file to your desired center and range. Keep the original starter map for others to use by adding a (*) to cause APRS to skip it when loading the MAPLIST.map file. As the number of points in your map grows, you may need to throw out some of the points which are beyond your area of interest. Use MAPFIX.bas to delete points. See the next section on map spawning. MAP SPAWNING: In the figure above, map A is the original starter map with the origin at O. 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 1000 limit, it is necessary to start new smaller area maps such as B, C, and D above to permit finer detail to be added. Spawning a new map is easy. Simply use a text editor to create a new mapfile and copy all of the features out of the original map that fit within the new map area. Then save this new map and add its name to the MAPLIST.map file giving a center and range appropriate to the new smaller area covered. Now add new roads and features in the area of interest. Notice that since the same origin and 120 pixel-per- degree scale are still used among all maps spawned from the same starter map, features and points can be moved among those maps by simply cut-and-paste. MAP CONVERSION: When it is desired to move features and points from one map to another map which has a different origin (X) or resolution, then use the MAPCNVRT.BAS program. First spawn a new map which contains all of the points that are to be moved. Then run the MAPCNVRT program giving the new origin and resolution. The resulting MAPTEMP.MAP file contains a copy of those features and points ready to be cut-and-pasted into the new map (Y) with the new origin (X) and resolution. This process is useful when creating finer detail maps of an existing area and you want to transfer the interstates and larger map features down to the finer detail map without having to re-do the data points. You can use MAPFIX.bas to add new points to a road when building a finer detail map, or to delete points when building a larger map where extra fine detail points are not needed.