Posts: 1
Joined: Fri Mar 11, 2011 5:58 pm

Ellipsoid definition

Fri Mar 11, 2011 6:02 pm

I have been looking at the WGS84 ellipsoid as defined in the program and do not think 1/f is correct. See example below:

WGS84 ellipsoid definition:
a = 6378137
E2 = 0.00669437999014132
1/f (my calc)= 298.257223562997
1/f (Fransom)= 298.257229164951

As you can see it the difference starts at the 6th decimal place and it is not a rounding error. A quick browse on the internet supports my definition of the ellipsoid. Looking at other datum definitions and entering my own new ones I believe the program is not calculating 1/f correctly after a and E2 are entered FOR ANY DATUM. If the program is mis-calculating 1/f to this degree what effect would it have on any co-ordinates transformed from WGS84 to some other datum?

Please can you respond with an explanation asap.

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