Great Circle Bearing map software

[Eric Scace]

   Great circle bearing map-generation software has not been made =
available to date because it is not easy!  I learned a bit about it when =
I was working with the author of GeoClock.

   Geoclock's database, for example, is derived off US Navy and CIA map =
databases (sanitized for sale to the public).  Coordinates are provided =
for something like every 10m of coastline, borders, etc. for all =
landmasses (islands, etc).

   Great circle charts need this level of detail (especially if they are =
physically large) because physical elements located at the antipodes =
(the outer edge) of the map are blown up hugely.  If one does not have =
this detail, the projection gets very jagged.

   The next problem is that the databases provided are not "clean".  (A =
similar problem exists for the USA database provided by the Census =
Dept.)  There are many typos and other errors in the database.  It takes =
thousands of labor hours to research and correct errors.

   Lastly, the clean database is huge.  While hugeness is less of a =
problem these days with CD drives, this is not something than one loads =
on a hard drive in a spare corner.

   Bottom line:  the value of the database, when kept current and =
"clean", and the storage requirements make it uneconomical to sell to =
hams for generating their own great circle charts.

   Geoclock will provide you a custom great circle chart (for projection =
on your PC) for any location for $30 per chart (the last time I =
checked).  I don't know how you value your free time, but $30 seems =
reasonable to me compared to the cash outlay for multi-gigibits of hard =
drives plus valuable software.  I can buy a lot of special Geoclock =
charts for different locations before it makes any sense to think about =
rolling my own...

   Geoclock is available on the Web as shareware (no great circle =
charts).  Use your favorite search engine.  You can order over the =
phone, through the Geoclock BBS, or via e-mail.

-- Eric K3NA
scace@msn.com

----------
From: 	owner-towertalk@akorn.net on behalf of Bill Cotter
Sent: 	1996 December 17 Tuesday 13:37 PM
To: 	towertalk@contesting.com
Subject: 	Great Circle Bearing map software

Hey gang,

I am in the process of locating/installing a 40m 4sqr and am looking for
software for creating a Great Circle Bearing map of planet earth =
centered on
my QTH lat/long. Over the years there have been many ads for services to
print one such custom map for an individual, but I have been unable to
locate a source for the software. I have found many programs to create =
the
bearing tables (ie: country, heading, distance, etc.), but none to =
create
the map. Has anyone seen such shareware, freeware, buyware, anyware?

Thanks,

Bill, N4ALG

 __________________________________________________________
|                                                          |=20
| Bill Cotter, N4ALG           e-mail: bcotter@pop.uky.edu |
| 173 Carolyn Lane               Home: (606) 887-5563,2402 |
| Nicholasville, KY 40536-9340   Work: (606) 323-6474      |
|__________________________________________________________|
=20


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