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Google Earth Coordinates vs. GPS Device Coordinates

#1 User is offline   Pigout 

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  Posted 06 October 2006 - 08:04 AM

I'm a little confused about Google Earth's GPS coordinates vs. my Garmin Gek301's GPS coordinates. They seem to be using different formats.

According to the Garmin manual I should be using MAP Datum WGS 84 and position format H D(degrees)M.M' .

OK, but Google Earth says Degrees, Minutes and Seconds and uses a slightly different format if I edit a placemark and look at the latitude and longitude of a location.

All I'm trying to do at the moment is to pinpoint a location on Google Earth, go to geocaching.com and search for caches in that surrounding area by entering the Google coordinate into the "WGS84 Datum" search box.

Of course it would also be good to be able to mark caches I've found, know that I'm using the right format in my Garmin device for entry of the cache locations, etc. Can someone help? I've search and search but can't find the answer. Guess I am very dense!!

Thanks!

This post has been edited by Pigout: 06 October 2006 - 08:05 AM


#2 User is offline   smartboyathome 

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Posted 06 October 2006 - 08:15 AM

Just enter the coordinates as it says on the cache page, it will accept it that way.

#3 User is offline   StarBrand 

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Posted 06 October 2006 - 08:18 AM

You can find converters at www.jeeep.com
or download fizzymagics useful utility

#4 User is offline   HaLiJuSaPa 

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Posted 06 October 2006 - 08:20 AM

For some reason Google Earth uses DD MM SS.S (degrees, minutes, and seconds to one decimal) for coordinates. This was the traditional way of showing latitude and longitude, I remember it when I first learned of these two concepts in upper elementary school in the late 70's.

But in the last decade or so, using DD.DDDDD (just degrees and the decimal) or more so DD MM.MMM (Degrees and minutes to the 3rd decimal) are more common. The latter is the official geocaching coordinate method and is usually the default way that most GPSrs show coordinates (though a GPS I used to own, the Galileo by the Whistler radar detector people, ONLY showed coords the Google Earth way; and it seems one of the two GPSr I now have, the Lowrance IWay 100M, ONLY shows it the geocaching way).

Most GPSr's nowadays have the ability to show coordinates in any of the 3 formats, so you could manually enter a waypoint the way it's shown on Google Earth, then ask the GPS to show it as DD MM.MMM format

Hope that helps!

#5 User is offline   Anatomist 

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Posted 06 October 2006 - 10:29 PM

View PostHaLiJuSaPa, on Oct 6 2006, 08:20 AM, said:

Most GPSr's nowadays have the ability to show coordinates in any of the 3 formats, so you could manually enter a waypoint the way it's shown on Google Earth, then ask the GPS to show it as DD MM.MMM format

Hope that helps!


The other way around is also true, you can setup google earth to show DD MM.MMM

This post has been edited by Anatomist: 06 October 2006 - 10:30 PM


#6 User is offline   briansnat 

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Posted 07 October 2006 - 04:56 AM

moving to correct forum

#7 User is offline   roygpa 

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Posted 07 October 2006 - 06:04 AM

View PostAnatomist, on Oct 7 2006, 02:29 AM, said:


The other way around is also true, you can setup google earth to show DD MM.MMM


How do I configure Google Earth to use DD MM.MMM?

Roy

#8 User is offline   TomandGina 

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Posted 07 October 2006 - 06:58 AM

View Postroygpa, on Oct 7 2006, 10:04 AM, said:

View PostAnatomist, on Oct 7 2006, 02:29 AM, said:


The other way around is also true, you can setup google earth to show DD MM.MMM


How do I configure Google Earth to use DD MM.MMM?

Roy


Look for an Options... or Preferences... menu item (depends if you are using the PC or Mac version). There is an option in the "View" tab for Lat/Lon as "Degrees" which is "xx.xxxxxx", or "Degrees, Minutes, Seconds" which is "dd mm ss.ss".

I leave my gps in "dd mm.mmm" mode which is what geocaching.com uses. You can enter a location in that format directly into google earth in the fly to search box. When taking a location from google earth and searching on the gc.com site, you can select decimal degrees on the search page, and use the location given by google earth.

Make sure your GPS is set for WGS 84 datum, otherwise your locations will be off. Even though the gc.com page says "WGS 84" for entering locations in "dd mm.mmm" format and "decimal degrees" for entering locations in "dd.dddddd" format, they both use the WGS 84 datum. It's just they way they labeled the boxes.

This post has been edited by TomandGina: 07 October 2006 - 07:01 AM


#9 User is offline   Pigout 

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Posted 07 October 2006 - 07:51 AM

View PostTomandGina, on Oct 7 2006, 06:58 AM, said:

View Postroygpa, on Oct 7 2006, 10:04 AM, said:

View PostAnatomist, on Oct 7 2006, 02:29 AM, said:


The other way around is also true, you can setup google earth to show DD MM.MMM


How do I configure Google Earth to use DD MM.MMM?

Roy


Look for an Options... or Preferences... menu item (depends if you are using the PC or Mac version). There is an option in the "View" tab for Lat/Lon as "Degrees" which is "xx.xxxxxx", or "Degrees, Minutes, Seconds" which is "dd mm ss.ss".

I leave my gps in "dd mm.mmm" mode which is what geocaching.com uses. You can enter a location in that format directly into google earth in the fly to search box. When taking a location from google earth and searching on the gc.com site, you can select decimal degrees on the search page, and use the location given by google earth.

Make sure your GPS is set for WGS 84 datum, otherwise your locations will be off. Even though the gc.com page says "WGS 84" for entering locations in "dd mm.mmm" format and "decimal degrees" for entering locations in "dd.dddddd" format, they both use the WGS 84 datum. It's just they way they labeled the boxes.


OK, think I've got it. Would appreciate confirmation from those in the know.

Google Earth on my Mac:
Set preferences to "Degrees, Minutes, Seconds". This looks to be the default.
Place marks show latitude - 41()41'52.60"N, longitude - 88() 8'13.70"W

Garmin geko 301:
Position format choices are - H D.D(), H D()M.M' and H D()M'S.S"
Looks like H D()M'S.S" is the correct choice? This is NOT the default.

Using the above, the Google Earth map location was pretty close to where I stopped my car on the way out of the dog park yesterday and marked the location in my Geko. It's probably within 15 feet.

Using my home as an example, I marked my spot on the sidewalk but Google Earth put me the edge of the street. Again probably within 15 feet and I think the accuracy may have been 16 feet. I need to do some more testing but does the Geko position format choice seem correct??

So how would I enter the park location in the WGS84 Datum latitude longitude search boxes on geocaching.com?

This post has been edited by Pigout: 07 October 2006 - 07:58 AM


#10 User is offline   ossumguywill 

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Posted 07 October 2006 - 08:05 AM

No, all that google earth does is make you write the coordinates with an apostrophe, a quotation mark and a space before you put the hemisphere symbol (like W or S) when you set the coordinate system to DMS. Just type it in like this:
00 00'00.00" N, 00 00'00.00" W
You can also insert the degrees sign after the first set of digits if you want to. On geocaching.com, enter the coordinates as shown above the coordinate entry box.

This post has been edited by ossumguywill: 07 October 2006 - 08:08 AM


#11 User is offline   TomandGina 

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Posted 07 October 2006 - 08:44 AM

You may be confusing two different things here.

WGS 84 is a datum. It is a standard that says how positions on the globe are determined from a given reference point.

Then you have the different coordinate formats. They all represent the same point, and all are using the WGS 84 datum:

3614'55.35" N 9636'53.95" W
3614.9226 -9636.89928
36.24871 -96.614988

You can paste any of the above coordinates into google earth and it will read them. GC.com can search by the two formats listed on the search page. As long as you are all speaking the same datum (which google earth and gc.com are, and you've set your GPS to use WGS 84) then any of the above formats would work.

As for the 15 foot accuracy, that's pretty good. The best you may see is around 7 feet with WAAS enabled on your GPS.

#12 User is offline   TomandGina 

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Posted 07 October 2006 - 08:47 AM

I should add that the accuracy also depends on the number of satellites your gps can see, as well as tree cover and signal reflections from nearby buildings or other tall objects.

The point I picked in the example was just a random click on the map in google earth. It looks like a good spot for a cache!

#13 User is offline   John E Cache 

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Posted 07 October 2006 - 08:49 AM

View PostPigout, on Oct 6 2006, 09:04 AM, said:

I'm a little confused about Google Earth's GPS coordinates vs. my Garmin Gek301's GPS coordinates. They seem to be using different formats.

According to the Garmin manual I should be using MAP Datum WGS 84 and position format H D(degrees)M.M' .

OK, but Google Earth says Degrees, Minutes and Seconds and uses a slightly different format if I edit a placemark and look at the latitude and longitude of a location.

All I'm trying to do at the moment is to pinpoint a location on Google Earth, go to geocaching.com and search for caches in that surrounding area by entering the Google coordinate into the "WGS84 Datum" search box.

Of course it would also be good to be able to mark caches I've found, know that I'm using the right format in my Garmin device for entry of the cache locations, etc. Can someone help? I've search and search but can't find the answer. Guess I am very dense!!

Thanks!
Entering and displaying are separate on Google Earth. It is pretty smart at figuring out what you entered. There are 60 minutes in a degree so 57.5 degress equals 57 degrees 30 minutes. If you enter two numbers GE guesses degrees and minutes. 60 seconds in a minute so three numbers are DMS. Also, You can drop loc or gpx files on GE:
  • Do a search in geocaching.com(zip code, home coords etc.)
  • At the bottom click check all and download
  • click save file
  • click open folder
  • drag the saved file from the folder onto google earth


#14 User is offline   roygpa 

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Posted 07 October 2006 - 03:00 PM

I guess I should have posed my question differently. What I meant was, is it possible to configure Google Earth so that when I put the pointer a certain place, it will return the latitude and Longitude in DD MM.MMM, so t hat I don't have to convert it before entering it into my GPS?

In Tools, Options, Show Lat/Long I see options of Degrees, Minutes, seconds,
or Degrees
or UTM

No biggie, it's not difficult to convert.

Roy

#15 User is offline   robertlipe 

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Posted 07 October 2006 - 03:45 PM

Change your GPS to match one of the options available. Better yet, write Google and ask them to add DD MM.MMMM as an option within Earth.

#16 User is offline   roygpa 

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Posted 07 October 2006 - 04:42 PM

I wandered over to the Google Earth Communiity and searched... only to find out that DD MM.MMM is considered obsolete, and then I found a kmz placemark file here:
Decimal minutes

that places a bookmark in the center of the screen and you just mover the map to the place that you want. Then it gives the coords in DD MM.MMM format.

Not perfect, but it works for me.

Roy

#17 User is offline   HaLiJuSaPa 

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  Posted 08 October 2006 - 12:52 PM

View Postroygpa, on Oct 7 2006, 04:42 PM, said:

I wandered over to the Google Earth Communiity and searched... only to find out that DD MM.MMM is considered obsolete, and then I found a kmz placemark file here:
Decimal minutes

that places a bookmark in the center of the screen and you just mover the map to the place that you want. Then it gives the coords in DD MM.MMM format.

Not perfect, but it works for me.

Roy



Obsolete? I would think that DD MM SS.S is the one no longer used, that is strange.

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