Winni
Posts: 2
Joined: Tue Mar 03, 2009 4:56 pm

Differences of calculated WGS 84 values

Mon Mar 16, 2009 2:59 pm

Measured values on-site:
Easting: 207214,842
Northing: 3636891,962
Measured values acc. to LGD 2006 and Libyan Transverse Mercator 2 deg. system
Output of CoordTrans program for WGS84:
32°51'30,56"N / 13°04'35,18"E
Expected Value acc. to GOOGLE Earth:
32°51'30,69"N / 13°04'34,83"E
Difference of abt. 10 m, bearing abt 293,85° E.T.N.
Please advise.
Thanks

bbulla
Posts: 282
Joined: Fri Jun 17, 2005 12:13 am
Location: Canada

RE: Differences of calculated WGS 84 values

Mon Mar 16, 2009 9:36 pm

I would say that either the coordinates you got from your GPS are not 100% accurate, or the images in GoogleEarth are not 100% accurate. I mapped your expected coordinate and it appears to be near some sort of building. Were you in the building when you got your original coordinate?? Or near it?? What kind of GPS did you use? Did you get your reading at the optimal time of day for that location?

From my experience using CoordTrans and ESRI products, CoordTrans always gives the proper result. I would suspect your GPS or Google Earth is the problem.

Brian

Winni
Posts: 2
Joined: Tue Mar 03, 2009 4:56 pm

RE: Differences of calculated WGS 84 values

Fri Mar 20, 2009 5:59 pm

Hi Brian,
Thanks for the explanation. Possibly you're right.
The stated (Easting/Northing) values have been measured by a local geometer. I've no information about the used instrument, but I'm sure that the measurement has been done accurately. Therefore I presume that GOOGLE Earth isn't accurate at 100% . Thanks again.
Winfried

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