[APG Public List] [APG Members] place names
john at jytangledweb.org
Wed Oct 27 21:36:03 MDT 2010
And since the actual latitude and longitude of a place won't change,
it is a simple matter (for a mathematician, engineer, or scientist)
to write down and program a set of equations that will uniquely
convert one set of coordinates to coordinates in the other coordinate
system. [Hint: represent the earth in spherical polar coordinates
and do the trigonometry. To a first approximation assume that the
radius of the Earth is constant. Advanced credit to those who don't
need to make that assumption! ;-) ]
If another coordinate system becomes common, you can bet Google
engineers will add "Coordinate System" as a selectable preference
in Google Earth and friends.
GPS replaced maritime navigation coordinates from Loran radio towers
and receivers. (I live only a few miles from the east coast inland
waterway and the Atlantic Ocean.) I think the last Loran radio
transmitter in NJ (the nation?) was just shut down in the past
year. Boat captains made the change over about a 10 year period.
I don't know about aircraft navigation, but I seem to remember that
they are still stuck on ancient navigation technology and don't
use GPS yet. !!??
On 10/27/2010 6:20 PM, Stephen Danko wrote:
> One thing to realize about the coordinates that can be obtained from
> either Google Maps or a GPS device is that the numbers refer to degrees
> latitude and longitude. Unless mathematicians decide to change the
> number of degrees in a circle or cartographers decide to change the
> location of the equator or the prime meridian, the actual latitude and
> longitude of a place won't change even when GPS technology changes.
> Furthermore, these coordinates can be used to find locations on both
> electronic maps and paper maps (such as US Topo Maps) that display the
> latitude and longitude.
> Kind regards,
> Stephen J. Danko
> *From:* Mark Rabideau <genealogy at eirenicon.org>
> *To:* Janice Sellers <janicemsj at gmail.com>
> *Cc:* apgpubliclist Posting <apgpubliclist at apgen.org>;
> jhrabideau at gmail.com; apgmembersonlylist at apgen.org; becky at pep-inc.com
> *Sent:* Wed, October 27, 2010 9:24:18 AM
> *Subject:* Re: [APG Members] [APG Public List] place names
> It is probably worth noting that commerical GPS is really only about 10
> years old and is primarily a US national system for establishing global
> location. To quote the ever popular WIkipedia "GPS is owned and operated
> by the U.S. Government as a national resource." As new GPS systems
> develop, there is likely to be change in nomenclature and other
> characteristics, as competing & complimentary global positioning systems
> reconcile and move towards international standards (at least that is how
> everything else seems to work in the technology realm). It is worth
> noting that there are at least two competing and one non-competing GPS
> system online or soon to be online- competing systems will be from the
> Chinese (Compass) and Europe Galileo (Europe); the non-competing system
> is a Russian military system.
> To me the biggest benefit of the current US GPS is that it makes the use
> of Google Earth and the like for genealogy software packages possible.
> But to my mind, maps continue to be a more stable and reliable long-term
> form of locational documentation for genealogical purposes.
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