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Main Boards => PowWow => Topic started by: VTer on August 07, 2010, 03:49:00 PM

Title: GPS unit compared to Google Earth
Post by: VTer on August 07, 2010, 03:49:00 PM
Just wondering if anybody has checked there GPS co-ordinates with the readout that shows on the bottom edge of the google earth screen. Mine seem to line up good east and west, but I'm south of the mark, north and south. Anyways, I thought it would be a good way of entering waypoints into my GPS for checking when I physically got there.
Title: Re: GPS unit compared to Google Earth
Post by: PowDuck on August 07, 2010, 04:54:00 PM
It's been pretty darned accurate when I've done that. i.e.: find a place on Google Earth, enter coordinates in GPS, go out and find place.

The north/south issue isn't surprising though. I've noticed lots of times a road on GE is in line E/W but usually lower (south) of the image.
Title: Re: GPS unit compared to Google Earth
Post by: Karebru on August 07, 2010, 05:12:00 PM
I've never compaired GPS to Google Earth, but I have noticed that the GPS on my boat is usually right on the money with the chart on the screen.
Every once in a while, though, it shows that I'm 100 yards or so up on dry land, traveling parallel to the river... It's an east-west river, so I guess it does read off north to south once in a while.   :dunno:
Title: Re: GPS unit compared to Google Earth
Post by: Canyon on August 07, 2010, 06:52:00 PM
you must have your GPS on the same map datum as Goole Earth which is set for WGS 84. If you change your GPS to match it will automatically adjust your lat long/UTM numbers so when you plug them into Google Earth they should be dead on.
Title: Re: GPS unit compared to Google Earth
Post by: VTer on August 07, 2010, 08:28:00 PM
Thanks Canyon. I tried it and your dead on!
Title: Re: GPS unit compared to Google Earth
Post by: frankwright on August 08, 2010, 10:25:00 AM
I had the same problem as I was trying to figure out my new Garmin and looking at Google Earth.

I had the Position Format wrong. After I changed it to match, it seems dead on.
Title: Re: GPS unit compared to Google Earth
Post by: BobW on August 08, 2010, 11:33:00 AM
That still isn't necessarily "dead on" accurate.  As an example, I have a GPS on my boat that was "calibrated/tuned" by a highly reputable company (Skipper Marine - sadly no longer in business), and it reads different than my out of the box Garmin Rhino 530HCX.

Google earth is also pieced together images, and can also have errors - all are "modest", and likely as accurate as your MAPS.  So, unless you are doing sub-centimeter survey work with RTK correction, and that equipment is not cheap or realistic for recreation, its "good enough".

Remember, you are using it (Google Earth) for free....

Dependig on conditions, 11' to 70' horizontal is "normal" anyways... vertical is much more out of that range of accuracy.