data/mwdbii/Pntinfo.txt

0001 Subject: PNT file format
0002 From: Paul B. Anderson (804) 853-7595 E-mail: pbander@infi.net
0003
0004   The PNT format was devised by Fred Popeschil and Antonio Rivera for their
0005 public domain Micro World Data Bank II (MWDBII) data base.  The PNT file is
0006 a binary file where each full record consists of 3 short integer values.
0007
0008                                 Possible
0009   1st short Integer value:      Header Values   Feature
0010                                 -------------   -------
0011                                 1               Data Level
0012                                 2               Data Level
0013                                 3               Data Level
0014                                 4               Data Level
0015                                 5               Data Level
0016                                 1000 -> 1999    coastlines
0017                                 2000 -> 2999    country
0018                                 4000 -> 4999    internal political borders
0019                                 5000 -> 5999    island
0020                                 6000 -> 6999    lake
0021                                 7000 -> 7999    river
0022
0023    2nd short Integer value:   Latitude in signed minutes (+/- 5400)
0024
0025    3rd short Integer value:   Longitude in signed minutes (+/- 10800)
0026
0027 POLYLINES:
0028 Latitude and longitude data in PNT files are arranged into polylines (or
0029 spaghetti). As an example (from MWDB-POLY), France is one polyline. All the
0030 lat/lon data points that make up France's coastlines and political borders
0031 are in one continuous line.
0032
0033 HEADER:
0034 The start of a new polyline is Indicated by a header value that is greater
0035 than 5. The list above, indicates all the possible polyline starting values.
0036
0037 DATA LEVEL:
0038 The data level (1 -> 5) determines the amount of detail in your map.  When
0039 writing programs using this data, level 1 is full detail and level 5 is the
0040 least amount of detail.
0041
0042 Level 1 -> plot all data points => 1
0043 Level 2 -> plot all data points => 2
0044 Level 3 -> plot all data points => 3
0045 Level 4 -> plot all data points => 4
0046 Level 5 -> plot all data points = 5
0047
0048 The start of each new polyline is understood to be at level 5.  The end
0049 of each polyline will be at level 5.
0050
0051 NOTEs:
0052
0053 Because the Short Integer is used, all latitude and longitude values
0054 are ROUNDED TO THE NEAREST MINUTE. This limits the usefulness of this
0055 data to small scale maps only.
0056
0057 Multiply the 2nd or 3rd short integer values by 2.908882086657222D-04
0058 to go from signed minutes straight to Radians.
0059
0060 Divide the 2nd or 3rd short integer values by 60 to go from signed minutes
0061 straight to Decimal Degrees.
0062