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README-cdb
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README-cdb
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========================================================================
README file for coastlines database directory
11-Apr-1994 K.Knowles knowles@sastrugi.colorado.edu 303-492-0644
National Snow & Ice Data Center, University of Colorado, Boulder
========================================================================
This sub-directory contains data files for map overlays. The data were
derived from three sources. All cil, bdy, and riv files were produced
from Brian Reid's (Decwrl) compressed binary data version of the CIA's
World Data Bank II (WDBII). The wdb files were produced using WDBII
data from the National Geophysical Data Center's (NGDC) "Global Relief
Data" CD-ROM. The wvs files were produced from the Defense Mapping
Agency's World Vector Shoreline, also available on the NGDC CD-ROM.
All files were clipped, joined, thinned, sorted, and reformatted for
use with the cdb (coastlines database) package developed at the
National Snow & Ice Data Center. The file name reflects the source of
the data, the level of detail, and the thinned resolution.
This directory should be set in the PATHCDB environment variable.
for example:
setenv PATHCDB $HOME/dmsp/cdb
Database file names should be set in the applications default files
or in the user's .Xdefaults file.
for example:
Popview.coastlinesFilename: cil1-50km.cdb
Popview.boundariesFilename: bdy1-50km.cdb
------------------------------------------------------------------------
Here's the database_info file from Brian Reid for cil, bdy, and riv data:
------------------------------------------------------------------------
The CIA World Bank II master information is a series of COBOL records,
specifying 5,719,617 individual vectors, which occupies about 130
megabytes of disk space. The "cbd" files here are compressed binary
encodings of it, collectively occupying about 15 megabytes of disk space.
These "cbd" files were produced from the original ASCII database by
Brian Reid at Decwrl.
The original database is available from the U.S. Government and is in the
public domain. The map database is divided into continents (North America,
South America, Europe, Africa, and Asia), and within continents it is
divided into "Coastlines, Islands, and Lakes" (cil files), "Rivers"
(riv files), "International political boundaries" (bdy files) and
"National political boundaries" (pby files). Each file is divided into
several thousand "segments", and each segment is divided into some number
of "strokes". The .cbd encoding of the database encodes each continent into
a directory and each division into a file.
The "rank" of segments within a file is an indication of what the segment
depicts:
In "Boundary" files (bdy):
01 Demarcated or delimited boundary
02 Indefinite or in Dispute
03 Other line of separation of sovreignty on land
In "Coast, Islands and Lakes" files (cil)
01 Coast, islands and lakes that appear on all maps
02 Additional major islands and lakes
03 Intermediate islands and lakes
04 Minor islands and lakes
06 Intermittent major lakes
07 Intermittent minor lakes
08 Reefs
09 Salt pans -- major
10 Salt pans -- minor
13 Ice Shelves -- major
14 Ice Shelves -- minor
15 Glaciers
In "Rivers" files (riv)
01 Permanent major rivers
02 Additional major rivers
03 Additional rivers
04 Minor rivers
05 Double lined rivers
06 Intermittent rivers -- major
07 Intermittent rivers -- additional
08 Intermittent rivers -- minor
10 Major canals
11 Canals of lesser importance
12 Canals -- irrigation type
Wrangell Island, off the coast of Siberia, seems to have been damaged
by a bug in the data compaction program.
------------------------------------------------------------------------
Here's the wdb_wvs.doc file from the NGDC CD-ROM:
------------------------------------------------------------------------
World Vector Shoreline (WVS) and World Data Bank (WDB) II Binary files:
Sources:
WVS: US Department of Defense, Defense Mapping Agency
WDB: US Central Intelligence Agency
The World Data Bank II outline files are digitized from navigational
charts to a working scale of approximately 1:3 Million, and represent
the "state of the art" in the mid 1970s. There are three files
composing the WDB-II set on this CD-ROM: coastlines, rivers and lakes,
and political boundaries (the last becoming increasingly obsolete!).
Some of the details contained in the original WDB files, such as
"order" of the elements (as related to size and importance of islands
or lakes) have been left out of these versions -- the full and
official WDB is available from the National Technical Information
Service, Springfield, VA.
The World Vector Shoreline data sets are given at several resolutions,
corresponding to 1:43 Million, 1:12 M, 1:3 M, 1:1M, 1:250 Thousand,
and "full" resolution, or about 1:100 thousand. The lower-resolution
sets have fewer points, are faster to plot, but appear more jagged.
Both the WVS and WDB files have been compressed into an efficient,
indexed binary data structure, accessible with the software included
on this CD.
Included software:
Plot software for compressed coastline files using Borland Turbo C (PC)
PLOT.C- main program- illustrates how to call WDBPLTC.C
WDBPLTC.C- function to be called from the user's program to access
the coastline file, extract a geographic window of data and call
CURVE.C to plot each string of geographic points. It requires the
memory handling functions in UTIL.C. Modifications from the original
by Jan Depner include dynamic memory allocation
and removal of internal map projection.
CURVE.C- function called from WDBPLTC.C- this function should be customized
for the user's application. It typically calls a map projection to
convert the geocoordinates to plotting coordinates and calls a plotting
routine to plot them.
UTIL.C- these functions are called from within WDBPLTC.C to allocate
and free up memory, give the operator a chance to abort the drawing, etc.
IPROJ.C- is a map projection utility that performs conversion between
geocoordinates and plotting coordinates. This demo uses just the
Linear (lat lon linear plot).
GTCLIB.C- these functions interface to the Turbo C library to perform
graphics functions. Not all of these functions are used in this demo.
EGAVGA.BGI- is the Turbo C graphics driver.
-----------------------------------------
Macintosh users:
The data access schemes in these subroutines work with Macintosh C
compilers as well, but the graphics calls in CURVE.C must be replaced
with the appropriate Mac toolbox calls. The Macintosh partition of
this CD-ROM includes compiled examples for extraction and display of
data from the WDB and WVS files.