Topo maps with lat and long grids.

[SarDragon]

A review of the GX55 manual reveals no provision for USNG.

[SARJunkie]

Florida is pushing VERY hard to to make USNG happen! right now most agaencies have transitioned.

[Eclipse]

Florida pushes a lot of things...

[Spaceman3750]

Here's a crazy idea... Learn both and use whichever one the lead agency tells you to use. It's not hard.

Now back to the regularly scheduled urination olympics.

[davidsinn]

I just found an online conversion tool from lat/lon to USNG

Latitude          Longitude        Datum            USNG
 
N38 52'22.08"    W077 02'06.86"    NAD 83 -> 18SUJ2344204629(NAD 83)

That's the output. In what way is that simpler? They claim the lat/lon to be the coordinates of the Washington monument but it is 3000m south east of there in the middle of the Potomac.

I ran that through google and it choked on it. Lat/lon is half a millenia old. What's wrong with it? It works. It's universal.

[SarDragon]

I just found an online conversion tool from lat/lon to USNG

Latitude          Longitude        Datum            USNG
 
N38 52'22.08"    W077 02'06.86"    NAD 83 -> 18SUJ2344204629(NAD 83)

That's the output. In what way is that simpler? They claim the lat/lon to be the coordinates of the Washington monument but it is 3000m south east of there in the middle of the Potomac.

I ran that through google and it choked on it. Lat/lon is half a millenia old. What's wrong with it? It works. It's universal.

I played with that converter the other night, anbd again a few minutes ago. I found a couple of things.

It appears that the datum for GE is NAD 27, and not NAD 83. I entered the converted NAD 27 lat/long into GE, and the error was much smaller - only about 700 feet.

I entered the USNG coordinates into GE, and it nailed the monument right on the dot.

I took a close look at a USNG tutorial online, and understood it quickly and easily. It was a good new trick for this olde dog.

YMMV.

[davidsinn]

I just found an online conversion tool from lat/lon to USNG

Latitude          Longitude        Datum            USNG
 
N38 52'22.08"    W077 02'06.86"    NAD 83 -> 18SUJ2344204629(NAD 83)

That's the output. In what way is that simpler? They claim the lat/lon to be the coordinates of the Washington monument but it is 3000m south east of there in the middle of the Potomac.

I ran that through google and it choked on it. Lat/lon is half a millenia old. What's wrong with it? It works. It's universal.

I played with that converter the other night, anbd again a few minutes ago. I found a couple of things.

It appears that the datum for GE is NAD 27, and not NAD 83. I entered the converted NAD 27 lat/long into GE, and the error was much smaller - only about 700 feet.

I entered the USNG coordinates into GE, and it nailed the monument right on the dot.

I took a close look at a USNG tutorial online, and understood it quickly and easily. It was a good new trick for this olde dog.

YMMV.

I put them into google maps because that doesn't require a download and is loaded on most smartphones by default.

[SarDragon]

Google maps and Google Earth are essentially equivalent behind the curtain.

[sardak]

N38 52'22.08"    W077 02'06.86"    NAD 83 -> 18SUJ2344204629(NAD 83)

That's the output. In what way is that simpler? They claim the lat/lon to be the coordinates of the Washington monument but it is 3000m south east of there in the middle of the Potomac.

The point is in the Potomac, but not 3000 meters. If you measure the distance between the point and the Washington Monument, it's about 1850 meters in a north/south line.
One nautical mile = 1852 meters = 1 minute of latitude.  If you change  38° 52' 22.08"  to  38° 53' 22.08" guess what? You get a point at the Washington Monument. The USNG coordinates change correctly, also.

It appears that the datum for GE is NAD 27, and not NAD 83.

From the Google Earth Users Manual (http://earth.google.com/support/bin/static.py?page=guide.cs&guide=22373&topic=23750&answer=148110)
Google Earth uses Simple Cylindrical projection with a WGS84 datum for its imagery base.

As with projections, there is more than one mathematical interpretation of the earth's shape. Google Earth uses WGS84 datum.
http://earth.google.com/support/bin/static.py?page=guide.cs&guide=22373&topic=23750&answer=148112

Google Earth and Maps are global products and WGS84 makes sense. About the only place you'll find anything in NAD27 are USGS topos. However, USGS is redoing them all in NAD83 (the federal civilian standard map datum) but its going to be a few more years until completion. The last ones they'll do are the "single edition" topos which are those which cover National Forests and are maintained by the US Forest Service. The old NAD27 ones will continue in use by those who have them - many, many of them.

I entered the converted NAD 27 lat/long into GE, and the error was much smaller - only about 700 feet.

That's because in the DC area the difference between UTM NAD27 and UTM NAD83/WGS84 is about 30 meters east/west and 220 meters north/south, for a composite of 222 meters = 728 feet.
I discussed that shift magnitude in my earlier post in this thread. What I didn't mention, but since we're on the topic, the lat/lon shift between NAD27 and NAD83/WGS84 in this area is only 8 meters south and 26 meters west. Where I live the lat/lon shift is 1 meter n/s and 50 meters e/w. You can almost ignore that.

Google maps and Google Earth are essentially equivalent behind the curtain.

Correct, both use WGS84 and a "pseudo-Mercator" projection, though the actual projections are somewhat different between them. One of the big differences though is that Google Earth, but not Google Maps, will accept input in coordinates other than lat/lon. One can copy and paste the USNG position being discussed  18SUJ2344204629  directly into GE (in version 6 anyway, I don't have anything running an older version) and have it plot out in the Potomac. Interestingly though, the coordinate options in GE list UTM but not USNG/MGRS.

For a converter between just about any datum and coordinate system, I recommend GEOTRANS from the National Geospatial Intelligence Agency (NGA) at http://earth-info.nga.mil/GandG/geotrans/
GEOTRANS runs in Microsoft Windows, LINUX and UNIX environments. Apple folks need to talk to the Government.

Mike

[SarDragon]

I think their DMS.S figure is wrong. Everywhere I measure the monument, it comes out at N38 52 22.08 and W 77 02 06.72.

Their NGS figure is right on.

YMMV.

[SARJunkie]

Tool Florida Emergency Mgt uses to convert / display:

http://floridadisaster.org/gis/kml/viewer.htm

[starshippe]

. . gpx files, which appear to be the standard for gps information interchange,
require the lat and lon to be in decimal degrees. there is currently no option
for any other format.
. . seems that rather than requiring everyone to speak a certain language,
it may work better for each group to speak their native language, and possess
an interpreter.

bill

[SarDragon]

There are several downloadable programs that will convert among the different unit systems.