When using Google Earth along side your Garmin or Magellan gps unit they must be set on the same unit of measurement. In Google Earth select tools, options, show Lat/Long. Select the unit of measurement that you are using on your gps.
If you are a Garmin gps user select Main Menu, Setup, units, and select from the drop down the appropriate measurement.
While some use UTM others use other measurements. Most of the surveys in my part of the country were done in hddd°mm.mmm’ format. And when finding “K” tags out in the woods I find this format in use. Federal agencies also use this format in fire reports. It is modified for aircraft dispatching because older aircraft guidance units will not except the last three digits. But to confuse things the same agency uses hddd°mm’ss.s when documenting law enforcement incidents. The nice thing about the CAD system I am familiar with is that the dispatcher enters the location in the format given and then system generates the lat/long is several formats allowing compatibility with a number of systems.
If I create a lat/long in by gps as N41°43.894 W122°38.139 and I need to covert it to UTM UPS in the field I can easily go to Main Menu, Setup, Units, and scroll down the options until I find UTM UPS. UTM UPS is commonly referred to as UTM. Your gps does the conversion for you automatically. It is not a math problem for the user. The same location becomes 10T 05303000 4620037 . Looking at a number of Forest Service and BLM maps I have the units of measurement used are hddd mm.mmm' , UTM, and Township, Range, Section, and Meridian. For an old duffer like myself
http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_systemDave in WV sent me some Google Images that he created before and after changing units. From the results of his imaging, and a little I did this morning it appears that now having both Google and your gps set on the same units gets the same result. I would not be surprised that Google reacted to the concerns that North Tree had regarding disaster mapping accuracy.
Google Earth is a neat tool. A while back I was given the location of a smoke from a citizen. The citizen was looking at the mountains about twenty miles from his location. The citizen provided a compass bearing and an estimated location. When I put the estimated location on a Google Earth Image and rotated it I immediately realized that the location was not correct. Because it was a thousand feet in elevation behind a peak from the reporting party. But using Map Source I created a route using the bearing, and viewed it in Google Earth. This displayed the search path for the smoke.
Units of measurement on a map can cause a lot of problems. As an example a lady calls an emergency dispatch center and says she has a problem. She tells the dispatcher that she is located at A-12.
The dispatcher quickly types A-12 in the computer. And does not get a result.
The dispatcher ask for additional information.
The woman becomes angry and says she is at #@%& A-12 on the map she bought from the service station.
Unfortunately A-12 can be a different location depending on the map being used.
In one County A-12 is a road number, in another it is meaningless.
The bottom line is that we need to be consistent when using units of measurement. Just remember that there are 66 feet to a chain, and 80 chains to mile.
Glanceblamm if I failed to answer your question please let me know.
