Graphics Plus/Graphics Plus.iso/amiga/mapping/wdbank.doc

Text File | 1991-12-22 | 21KB | 497 lines

Documentation contents:


INTRODUCTION

    Background (MS-DOS)
    Micro WDB II File Composition
    Disclaimer

WORLD DATA BANK II (Amiga) Display Routine, Version 2.2

    Overview
    Instructions For WDB
        Running WDB
        Forcing Use of a Single Data File
        Adjusting Aspect Ratio
        Navigating The Display
        Choosing A New Vantage Point
        Known Bugs
    Instructions For SAT
    Instructions For SELECT
    Credits


_____________________________________________________________________
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



~~~~~~~~~~~~~~~~~~~~~~~~~~
INTRODUCTION
============
~~~~~~~~~~~~~~~~~~~~~~~~~~

     The following information is from the original MS-DOS
     version of the WDB-II program, written by Fred Pospeschil.
     It explains the background of the CIA derived map data
     for those who are interested (or might have the resources
     to replace the data with something more current).


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The full WDB-II is a digitial map data base produced by the Central
Intelligence Agency (CIA) and distributed by the National Technical
Information Service (NTIS), U.S.  Department of Commerce, 5285 Port
Royal Road, Springfield, VA, 22161.  Micro WDB-II is a highly
compressed version which is suitable for use on micro computers and
was put in this configuration by Micro Doc.  Before describing Micro
WDB-II a few words should be said about the source file - WDB-II.  The
following paragraphs are paraphrased from the NTIS overview of WDB-II.

   WDB-II is a digitial representation of the world coastlines
   and boundries suitable for use in automated mapping systems.
   It contains approximately six million discrete geographic
   points and was digitized using all available sources of
   information.  Map scales used range from 1:750,000 to
   1:4,000,000 with a nominal scale of 1:3,000,000.  These points
   are grouped by and identified as describing (1) coast lines,
   (2) country boundries, (3) state boundries (USA only), (4)
   islands, (5) lakes, and (6) rivers.  Each of these groupings
   is further broken down into features and subordinate
   classifications/ranks.  These ranks are hierarchically
   structured, and are also used for plotting symbol definition.

   WDB-II, as provided by NTIS, is in a 20 character format
   on five 9 track EBCDIC one-half inch magnetic tapes.  This data
   base consists of two types of records, one for the line segment
   identifier data, and the other for the latitude and longitude
   values of each discrete point making up the line segment.  In
   this format latitude and longitude values are recorded only as
   integers in degrees, minutes, and seconds.  WDB-II is available
   for $660.00 (Order Number PB-271 874 SET/HBG).

Clearly, WDB-II is an excellent data source when making large (4 x 6
foot) plots on a mainframe or minicomputer.  It is, however, somewhat
large (150 - 200 megabytes) for use on microcomputers.  Even on the
larger commercial online graphics systems, many points have to be
filtered out before generating displays.  For this reason many people
have spent considerable time over the past to filter and compress this
data into a form which could be used in desktop computers.  To these
people we wish to express our appreciation - particularly Antonio
Riveria who provided us with a copy of the latest download of the
file.


Background
==========

The present version began as a three megabyte ASCII text file which
contained some 179,000 points selected from all six of the line types
described above.  This file was then converted into a sixteen bit
integer format which reduced the size to just over one megabyte. Since
this was still a little large for most five inch disk formats the file
was divided into six files - one for each of the six line types.  The
coast line file was further divided into two files as it was over 400
KB.  With this processing completed the file was configured such that
it could be readily moved to most desk top microcomputers using the
MSDOS disk format.  The following table provides a brief statistical
overview of the six line types which are contained in the data base.


Micro WDB-II File Composition
=============================

   Detail  COAST  COUNTRY  STATE  ISLAND   LAKE   RIVER   Total
   Level   .PNT   .PNT     .PNT   .PNT     .PNT   .PNT

     1     29150     8573    798   13781    5886   11146  69339
     2     35077    10172    959   16077    7080   13217  82599
     3      5470     1496    153    2524    1023    1817  12526
     4      4000     1249    101    1945     820    1254   9502
     5      1478      869    248     844     309     760   5365
   Total   75175    22359   2259   35171   15118   28194 179331

   Lines     208      301    111     344     103     196   1263

   Size (KB) 449      134     14     211      90     169   1067

The above table shows the number of points which are in each file and
for each level of detail.  It also shows the number of line segments
in each file and the file sizes in kilobytes.

Detail level 5 contains the fewest points and produces the least
detailed graphics image.  The points at each level of detail are
additive to the points at all lower levels.  For example, when using
detail level 4 the points from both levels 4 and 5 must be used /
retrieved.  Therefore, if one were drawing coast lines at detail level
4, a total of 5478 (4000 + 1478) points would be processed. These 5487
points will describe 208 line segments of various lengths.

    [NOTE: For the Amiga version, the structure of the data
    as described above has been altered.  Detail level 1 now
    incorporates all data from the lower levels.  It also
    combines data from each of the six groups into a single
    file.  Lower detail level files are subsets of the detail
    level 1 file, and similarly incorporate all data from
    levels below them.  The statistical distribution of the
    data points otherwise remains as described.]

Note that the same number of line segments exist at all levels of
detail.  For example, regardless of which level of detail is selected,
there will always be 208 line segments described by the coast line
data file.  In some cases, mostly in the islands file, line segments
degenerate to single points at the lower levels of detail.  Therefore,
programs which process this data must check to see whether each line
segment header record is followed by a point record or another line
segment record.  More will be said about this later.

Actual use of the data in these files has shown that most displays
which cover a reasonably large area do not need all of the detail
provided at level 1.  A large area would be a major portion of the
U.S.  For large area plots level 3 or 4 is normally sufficient and
greatly reduces the number of points which must be processed.


Disclaimer
==========

This product contains/uses data and/or code placed in the public
domain by Fred Pospeschil and Antonio Riveria.  Original coordinate
data was created by the Central Intelligence Agency.

ALL USERS OF THESE MATERIALS ARE TOTALLY RESPONSIBLE FOR THEIR USE AS
THESE MATERIALS ARE PROVIDED WITHOUT EITHER EXPRESS OR IMPLIED
WARRANTIES OF ANY KIND.

For information related to the original MS-DOS version only:

    Fred Pospeschil
    3108 Jackson St.
    Bellevue, NE 68005
    402-291-0795  (6-9 PM Central)

_____________________________________________________________________
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


WORLD DATA BANK (Amiga) Display Routine, Version 2.2



~~~~~~~~~~~~~~~~~~~~~~~~~~
OVERVIEW
========
~~~~~~~~~~~~~~~~~~~~~~~~~~

This program displays the CIA database of the geography of the world.
The executable file is under 11K, and its takes about 137K to execute,
including hi-res interlace screen and intuition interface.

Features:

    ╖  Slider gadgets for adjusting latitude, longitude and
       magnification factors
    ╖  Integer arithmetic for scaling, hence faster calcs
    ╖  Area clipping to avoid spending time plotting off-map points
    ╖  Compensation for monitor "stretch" (aspect ratio distortion)
    ╖  Automatic centering of next display from any point in current
       display
    ╖  Choice of cylindrical or spherical projection

The files in this set are described as follows:

LEVIATHAN.LHA   --   This enormous archive conatins the master 1.1 Meg
        data file for use with both the WDB and SAT display programs.
        The Big File, WDB.1.ALL, contains the data points in all six
        groups described above.  It can be broken down by the SELECT
        program into four smaller subsets named WDB.2 through 5.ALL.
        (WDB.5.ALL has also been provided separately to allow you to
        run the program without extracting this archive).  These
        smaller data files also will contain data from all six groups,
        but provide correspondingly faster drawing and less detail.
        The WDB.5.ALL subset furnished is the smallest, fastest, and
        least detailed.

SAT   --   This executable program draws a spherical view of the Earth
        from a fixed altitude approximating 30,000 miles.  It uses the
        WDB.5.ALL data file (the smallest, with least detail).  The
        latitude and longitude of your vantage point are adjustable.

SAT8   --   This is a special version of the SAT program above for use
        ONLY ON MACHINES EQUIPPED WITH A MATH CO-PROCESSOR.  *WARNING!*
        This program *WILL CRASH* if run on a machine not so equipped.

SELECT   --   This program may be used to create one or more of the
        four data files which are subsets of The Big File.

WDB   --   The World Data Bank executable program draws a cylindrical
        projection of the Earth.  Your vantage point is adjustable in
        latitude, longitude, and "altitude" (magnification factor).
        WDB automatically chooses one of the five data files to use
        based upon the magnification factor selected.

Other files   --   Also included are icons for Workbench executable
        programs (WDB.info, SAT.info), along with smaller alternate
        icons for each (WDB.alt.inf, SAT.alt.inf).  To use the alter-
        nate set of icons, simply delete WDB.info and SAT.info from a
        CLI, then rename WDB.alt.inf as WDB.info and SAT.alt.inf as
        SAT.info.


~~~~~~~~~~~~~~~~~~~~~~~~~~
INSTRUCTIONS FOR WDB
====================
~~~~~~~~~~~~~~~~~~~~~~~~~~

You may run WDB or SAT using the smallest (least detailed) data file
right now simply by clicking on either icon.  If you wish to see
greater detail you'll need to dissolve the LEVIATHAN.LHA archive,
placing the resulting WDB.1.ALL file in the same directory as the WDB
and SAT programs.  As explained below, you will probably want to use
the SELECT program to create the intermediate data files between The
Big File and WDB.5.ALL, but it's not necessary, especially if disk
space is too tight to waste on redundant data.


Running WDB
===========

To call it from CLI, type:  WDB <optional data file name>
To call it from Workbench:  double click on the WDB icon


WDB Automatically selects the input file based on the magnification
factor chosen according to the following scale:

    mag  0.85 -   2.00   --> wdb.5.all   (   25,890 bytes)
    mag  2.00 -   6.00   --> wdb.4.all   (   82,080 bytes)
    mag  6.00 -  12.00   --> wdb.3.all   (  156,960 bytes)
    mag 12.00 -  36.00   --> wdb.2.all   (  652,428 bytes)
    mag 36.00 - 125.00   --> wdb.1.all   (1,068,408 bytes)

The name of the file being shown appears in the lower right of the
Control Window.  If the automatically selected file is not available
in the current directory, the next most accurate file (lower numbered
file) available is used.  Note that the size of the file and the
detail available for display increases for *lower numbered* files.

Using various files allows for displays of greater magnification to
maintain better detail without the time penalty of passing through the
largest file for displays which require lesser detail. Perhaps someone
will have some better ideas for correlating the magnification scale to
the different data files.  Speak up!


Forcing Use of a Single Data File
=================================

From CLI, specifying a datafile on the command line will cause WDB to
supress automatic file selection, instead using only the file
specified.  For example, "WDB  WDB.3.ALL" will display only points
from the file WDB.3.ALL.


Adjusting Aspect Ratio
======================

There is a Distortion Comp(ensation) factor control designed to
compensate for monitor "stretch" that will be different for different
monitors.  The program defaults to a value of 1.2, figured at the
equator, which seems to work best with the 1080 monitor.  It may
require some experimentation to find a setting that produces
acceptable results with other monitors.  Try looking at the shape of
Africa on a good globe and adjust the value in the Distortion Comp
text gadget until the shape of Africa on screen approximates that of
the globe.


Navigating The Display
======================

Using one of the available data files, WDB draws a cylindrical
projection of the world's coastlines, political boundaries (including
states in the U.S.), islands, rivers, and lakes.  The default vantage
point is at the junction of the equator and the Greenwich meridian.
A default magnification factor of 1.0 provides a projection of the
entire globe.

On screen is a control panel offering an intuitive set of controls.
They include both text gadgets and sliders for selection of the
longitude and latitude in degrees and minutes, and the "altitude"
(magnification factor) of your vantage point over the earth.  You may
adjust the sliders to an approximate value, or enter a precise value
in the text gadgets from the keyboard.  Menu items allow you to
hide/show the menu bar and remove/restore the control panel for screen
captures.  The PLOT button draws a screen according to the control
panel settings; the QUIT button quits the program.  A drag bar on the
control panel allows it to be moved to a different location on screen.

Maps are drawn with colors which indicate the class of data points to
which they belong.  Continental coastlines are dark green, islands are
bright green, rivers and lakes are dark and light blue, respecively,
major political boundaries are red and minor ones (states) are yellow.

At greater magnifications, and especially with the more detailed data
files, the program may at times appear to halt momentarily.  This is
normal, as the program clips data which falls out of bounds of the
window displayed on screen.  When drawing is concluded the control
window will reappear.

If you end up with a completely black screen when the control panel
reappears, you've chanced upon a section of the globe which is
entirely devoid of features, such as an ocean.  To regain your
bearings, reduce the magnification factor and replot.


Choosing A New Vantage Point
============================

If you haven't a clue to the latitude and longitude of a location
you'd like to examine, WDB has a feature which allows you to select a
point on the current display with a click of the Left Mouse Button.
This will set both the longitude and latitude to that point, which
becomes the vantage point for the next display.  To avoid having a
desired vantage point end up off the screen, you should make the
selection of your target vantage point before experimenting with
greater magnification factors.  [See "Known Bugs"]


Known Bugs
==========

I've noticed that when the magnification factor is low (around 1.0 -
3.0), the mouse pointer location does not convert very accurately into
longitude and latitude.  I'm not sure why.  Perhaps rounding. (??)
The WDB program uses integer arithmetic (i.e., fixed-point math) to
gain speed.  This introduces rounding.



~~~~~~~~~~~~~~~~~~~~~~~~~~
INSTRUCTIONS FOR SAT
====================
~~~~~~~~~~~~~~~~~~~~~~~~~~

This program displays a single data file as a two-dimensional
projection of a sphere.  Unlike WDB, SAT's "altitude" is fixed at
around 30,000 miles.  Therefore SAT does not use multiple data files.
In this version the program expects to read the smallest, fastest, and
least detailed data file (WDB.5.ALL) since not much detail is visible
at this altitude.

Slider gadgets allow you to change the coordinates of the nearest
visual point of the sphere (your vantage point).  The vertical slider
adjusts latitude; the  horizontal one is for longitude.  You may also
choose to enter a specific number (in degrees) directly via the text
gadgets.  In this version, SAT does not allow the selection of
latitude and longitude coordinates from the mouse pointer.

There are two versions of this program:

    SAT  -  the regular version
    SAT8 -  a special version for those with M68881 math co-processors.

    NOTE:  DO NOT ATTEMPT TO RUN SAT8 IF YOUR SYSTEM IS NOT EQUIPPED
           WITH A 68881 MATH CO-PROCESSOR OR A CRASH WILL OCCUR.

Both programs use the same data files as WDB, although in the current
version, both look for a file called "WDB.5.ALL".  If you prefer to
view more detail (and can afford the wait) you may spoof the program
into using a different data file by renaming it as WDB.5.ALL.  Simply
copy one of the more detailed (lower numbered) files to a different
directory under the name of "WDB.5.ALL" and run SAT from that
directory.

For example, if you have the SAT program on df0:, type in a CLI:

    cd ram:
    copy df0:wdb.4.all ram:wdb.5.all
    df0:sat

SAT has many more calculations to complete than does WDB to plot a
map, hence it takes quite a bit more time.  Here, too, the display may
appear to halt for a period during the drawing process.  This is
normal.  When drawing is completed, the control panel will reappear on
screen.



~~~~~~~~~~~~~~~~~~~~~~~~~~
INSTRUCTIONS FOR SELECT
=======================
~~~~~~~~~~~~~~~~~~~~~~~~~~

The SELECT program is used to extract lower level data segments from a
higher level data file.  This program enables us to put the entire WDB
collection on one disk.  The price to be paid is that you must extract
the files named WDB.2.ALL, WDB.3.ALL and WDB.4.ALL from The Big File
yourself (if you intend to use them).  Note that it's not manadtory to
extract these files; both WDB and SAT will work with any single data
file or any combination (be sure to read the Instructions For SAT).
By choosing not to extract the three intermediate files you'll lose
only the speed advantage gained by not sifting through The Big File
for low and medium magnification viewing.

All four lower level data files (WDB.2 through .5.ALL) are merely
subsets of The Big File, and SELECT can extract any one of them
directly from it.  Similarly, each lower level file is a subset of all
higher level files, and SELECT can extract any lower level from any
higher level file.  Here, as elsewhere in this document, "lower level"
refers to filenames which are numerically HIGHER.


To use SELECT from the CLI:  SELECT <sourcefile> <destfile> <level #>

The level number of the source file must be numerically lower than the
level number requested for the new file.  The program will copy from
the source file to the destination file only the records with a level
number greater than or equal to the requested level number.

For example, to create WDB.4.ALL from The Big File enter:

   SELECT  WDB.1.ALL  WDB.4.ALL  4



~~~~~~~~~~~~~~~~~~~~~~~~~~
CREDITS
=======
~~~~~~~~~~~~~~~~~~~~~~~~~~

The program is the work of

    Mike Groshart:    basic design; porting from Pascal
    Bob Dufford:      intuition interface; speed optimization

Send us further suggestions and bugs to be fixed in care of:

    Amiga Users of the Heartlands
    P.O.Box 1432, DTS
    Omaha, NE.  68101

E-mail:

    Larry's Hot Tub: 402-571-4316  [1:285/15.0@fidonet]

Internet:

    [e-mail]
    [e-mail]

Or route a message through Portal or BIX ID: cletus



World Data Bank II for the Amiga, version 2.2 by Bob Dufford and
Michael Groshart.  This product uses data and code originally placed
in the public domain by Fred Pospeschil and Antonio Riveria.  Original
coordinate data was created by the Central Intelligence Agency.
Your tax dollars at work.

Anyone with access to a more recent version of the coordinate data
is welcome to provide it; a lot has happened to the world's political
boundaries since this was first released.    :-7